![Foreword
Fuzzy Logic in the Semantic Web: Coveringa
Missing Link
1. Introduction
During recent years, important initiatives have led to reports of connections between Fuzzy
Logic and the Internet. For example, at the initiative of Lotfi Zadeh and Masoud Nikravesh,
FLINT meetings ("Fuzzy Logic and the Internet") have been organized by BISC ("Berke-
ley Initiative in Soft Computing"). The proceedings of the FLINT 2001 workshop [I] and
of the NAFIPS-FLINT2002 Joint International conference [2] have been published. Mean-
while, scattered papers were published on Fuzzy Logic and the Semantic Web. A special
session, "Fuzzy Logic in the Semantic Web, a New Challenge", was organized during the
IPMU 2004 conference, at Perugia, Italy [3]. The idea for the present book came from en-
thusiastic authors and participants at that well-attended session, including: Trevor Martin,
Ernesto Damiani, Umberto Straccia and Henrik Legind Larsen. More recently, in Febru-
ary 2005, the first workshop on Fuzzy Logic and the Semantic Web [4] at Marseille was
attended by European experts in the field (they are all contributors to this book, too). This
volume, the first in the new series Capturing Intelligence, shows the positive role Fuzzy
Logic, and more generally Soft Computing, can play in the development of the Seman-
tic Web, filling a gap and facing a new challenge. It covers concepts, tools, techniques
and applications exhibiting the usefulness, and the necessity, of using Fuzzy Logic in the
Semantic Web.
2. The Semantic Web and Fuzzy Logic
Most of today's Web content is suitable for human consumption. The Semantic Web is
presented as an extension of the current web in which information is given well-defined
meaning, better enabling computers and people to work in cooperation. For example,
within the Semantic Web, computers will understand the meaning of semantic data on
a web page by following links to specified ontologies. But while the vision of the Semantic
Web and associated research attracts attention, as long as two-value-based logical methods](https://image.slidesharecdn.com/71317-250615103929-fea58a89/85/Fuzzy-Logic-and-the-Semantic-Web-1st-Edition-Elie-Sanchez-Eds-11-320.jpg)
![Foreword
4. Concluding thoughts
These are exciting times in the fields of Fuzzy Logic and the Semantic Web, and this
book will add to the excitement, as it is the first volume to focus on the growing connec-
tions between these two fields. This book will be a valuable aid to anyone considering the
application of Fuzzy Logic to the Semantic Web, because it contains a number of detailed
accounts of these combined fields,written by leading authors in several countries. The field
of Fuzzy Logic has been maturing for forty years. These years have witnessed a tremen-
dous growth in the number and variety of applications, with a real-world impact across a
wide variety of domains with humanlike behavior and reasoning. And we believe that in
the coming years, the Semantic Web will be a major field of applications of Fuzzy Logic.
Paraphrasing Lo@ A. Zadeh [5], we can say that "in moving further into the age of ma-
chine intelligerlceand automated reasoning, we have reached a point where we can speak,
without exaggeration, of systems which have a high macl~ineIQ (MIQ)... In the context
of the Sernalztic Web, MlQ becomes Semantic Web IQ, or SWlQ, for short"
References
[I] "New Directions in Enhancing the Power of the Internet" (Proceedings UCBIERL, Berkeley, Memo
No M01128, August 2001) and "Enhancing the Power of the Internet", M. Nikravesh, B. Azvine, R. Yager,
L.A. Zadeh (Eds.),Springer-Verlag, 2004.
[2] NAFIPS-FLINT 2002 Int. Conf., IEEE SMC Proceedings 02TH8622, New-Orleans, 2002.
[3] IPMU 2004, Special Session "Fuzzy Logic in the Semantic Web: a New Challenge", IPMUOlk3dipmat.
unipgit, Perugia, Italy, 2004, Proceedings, pp. 1017-1038.
[4] "Fuzzy Logic and the Semantic Web" Workshop, Extended abstracts available at http://waw.lif.univ-
rnrs.fr/FLSW, Marseille, France, 2005.
[5] L.A. Zadeh, "Web Intelligence and Fuzzy Logic - The concept of Web IQ (WIQ)", Invited talk at the
2003 IEEEMC Int. Conference on Web Intelligence (WI 2003), Halifax, Canada, available at n-ww.comp.
hkbu.edu.hkllAT03/InvitedTalkl
.htm.
Acknowledgements
I would like to take this opportunity to give special thanks to all the contributors and also
the reviewers for their commitment, hard work and time spent writing the variouschapters.
Without their efforts, this volume could not have come to fruition.
Elie Sanchez
Laboratoire d'Infonnatique Fondamentale
BiomathCmatiqueset Informatique 3ICdicale
FacultC de MCdecine, UniversitCde la MCditerranke
Marseille. France
September 2005](https://image.slidesharecdn.com/71317-250615103929-fea58a89/85/Fuzzy-Logic-and-the-Semantic-Web-1st-Edition-Elie-Sanchez-Eds-15-320.jpg)
![1. Introduction
During the 2004 WWW conference, Tim Berners-Lee, the spiritual leader of the semantic
web community, made a statement that might impact further research on semantic web
foundations. Asked whether it is necessary to have a representation for uncertainty on the
layered semantic web stack, his answer was basically "no". Knowing about the impact
of a person like Berners-Lee, this view might have great impact on the community and
hence on unfortunate students and researchers funded for the development of uncertainty
calculi for the semantic web. But aside from personal considerations, this answer can be
challenged on many levels. After all, history has shown many times that "the revolution
eats its children".
When talking about extending the kinds of logical inference used in local or global
knowledge bases, we have to be aware of the different ways in which this can be done.
The semantic web standard assumes a monotonic bivalent logic. Bivalent means that state-
ments are either true or false; no third possibility, such as unknown, exists, nor anything in
between true and false. In the remainder of the paper we will refer to these bivalent logics
as FOL (first-order logics).
Research in logic has produced a plethora of different formalisms which are more or less
used in real-world applications. There are many-valued logics, continuous-valued logics
with different semantics of their value assignments, such as fuzzy logics and probabilis-
tic logics [13,15], non-monotonic logics [38], paraconsistent logics [5] and combinations
thereof [lo]. One can make a case for the use of any of these logics for different applica-
tions. The question for semantic web researchers is, whether to augment the famous layer
cake by adding a different layer for non-bivalent and/or non-monotonic logics or whether
these ausmentations should exist locally, for groups of agents that agree to their own rep-
resentation of non-FOL statements.
Berners-Lee's main argument for the rejection of a representation of uncertainty at the
very basis of Semantic Web formalisms was their lacking scalability. This is a strong argu-
ment. For example, in order to do complete probabilistic inference on dependent objects in
a Bayesian Network or any other technology for probabilistic inference, potentially every
path through the network has to be taken into account. The same holds for any kind of
non-monotonic logic. Given that, even in the case of FOL, such as SHIQ [18] or similar
Description logics, inference cannot be done in a computationally efficient way, it seems
mandatory to keep the evaluation of statements local.
One major problem that monotonic knowledge bases face is that of inconsistency. In a
monotonic logic, such as each of the various flavors of bivalent Description Logics and
hence OWL, it is assumed that if a true statement can be derived from a set S of facts
and rules, then it can also be derived from every larger set Sf that contains S. This is an
appealins assumption to make, because it allows reasoning to be local and to only take into
account the rules and facts that are immediately necessary to deduce a new statement. But
it is also an unrealistic assumption to make, because the world, even the formalized one,
is full of contradictions. And the more this world of formal statements grows, the more
likely it i$ that a contradiction occurs. For this reason, the CYC@Ontology is partitioned
into consistent micro theories or contexts [311. Inconsistencies with other micro theories
are explicitly stated. To give an example of how easily inconsistencies can occur when we
get to know more about a domain, we cite an example that is widely used in A1 textbooks.
It involves birds. We will state the knowledge base informally:](https://image.slidesharecdn.com/71317-250615103929-fea58a89/85/Fuzzy-Logic-and-the-Semantic-Web-1st-Edition-Elie-Sanchez-Eds-22-320.jpg)
![6 Clr. Tf~ort~ns
orld A. Sherh
acquaintance Paul that Peter and Mary broke up recently. While I might still have propa-
gated it as a rumor that I did not really trust to Cathy, she might have told it as a fact to
Marc u ho was Peter's best friend but always had his eyes on Mary. After asking her out on
a date. his Friendship with Peter was shattered. If every link in this gossip chain had kept
the information that it was just a rumor, Marc and Peter would be drinking beer now.
1.2. Itlfomation retrieval
In information retrieval, we are dealing with all sorts of noisy data. Web search engines
and proposed question answering systems that are based on information available on the
Internet or in local ontologies will on average yield results that are not totally relevant or
reliable. The annotation of data with metadata will improve this situation, but not funda-
mentally change it. Hence, an estimate of relevance or truth, delivered together with the
answer or answer set, would be desirable.
Recently, more statistical techniques have emerged in Internet search engines. While
Google's page rank [8] measures the popularity of a page and makes the implicit assump-
tion that popularity is somewhat linked to importance, other search engines use clustering
to order their search results. The Vivisimo search engine [42] builds a hierarchy for the
search results using a hierarchical clustering technique.
The Vivisimo approach is only the first of many search engines that give a hierarchical
structure of their search results. We will also encounter situations in which we want to
build ontologies or topic maps on the fly from sets of documents that have not yet been
classified' [21,29]. Any automatic approach to ontology generation, be it statistical, using
pattern based, NLP or other techniques, must be uncertain in nature and the map must
reflect its own uncertainty about the inferred knowledge.
In the Semantic Web context, this uncertainty cannot just be stored within the generating
or retrieving agent, but must be propagated through the deductions or other reasoning steps
that are performed with the information. In a future situation, when a derived fact is anno-
tated with the trace of its derivation (i.e. its provenance information), this will become
clear. In community based knowledge accumulation, such as an augmented "Semantic
Wikipedia" project [41], the community could assign degrees of belief to the formalized
facts. Each agent in turn can assign degrees of belief to selected ontologies or single facts
within ontologies. The latter is an individual assignment and doesn't require a formaliza-
tion, but the former needs to be made available to general purpose reasoners, if we want the
Semantic Web vision of connectivity between heterogeneous knowledge sources become
a reality.
For the next generation of web search engines, question answering machines, it will be
crucial to have a powerful representation of vagueness, because the terms humans use to
describe the world will be vague and ambiguous [28,30,40].
1.3. Sev~antic
Web
Semantic heterogeneity is an inherent reality of the Internet. It is possible to encompass
all types of syntactic, schematic and semantic heterogeneity that have been discussed in
I The term ontology usually implies a rigid knowledge representation which meets formal criteria of inheritance
or soundness/completeness issues. The tenn topic map has a less formal connotation.](https://image.slidesharecdn.com/71317-250615103929-fea58a89/85/Fuzzy-Logic-and-the-Semantic-Web-1st-Edition-Elie-Sanchez-Eds-24-320.jpg)
![On !he expresshvness of rhe languagesfor rhe ser?ranricweb 7
research on heterogeneous databases [22,24,33].This diversity makes it the most useful,
ubiquitous and unbiased collection of knowledge that has ever existed. The challenge to
a computational use of this smorgasbord of opinions is to keep the diversity while still
having a sound basis for computation. Inability of first order to model heterogeneity even
in relational databases was conclusively discussed [26]. In the real world realization of the
Semantic Web, very few ontologies will be consistent with each other. These inconsisten-
cies can arise for multiple reasons. The easiest resolution is that of ambiguity in terns and
actual formalization while still agreeing on the conceptualization as such. But ontologies
can also be fundamentally inconsistent, because the ontological and metaphysical basis is
different, i.e. the ontologies don't share the same view of the world or their domain, or the
factual knowledge used to populate them come from different sources whose observations
are inconsistent with each other.
This paperis meant to show that,despite computational disadvantages, many signs point
b-
towards incorporating the representation of more powerful semantics into the Semantic
Web layer cake. While it is computationally impossible to logically track every statement
on the web and use it in every logical inference, a restriction to deduction within local on-
tologiesbased on FOL will only exploit the local knowledge, but never help acquiring new
knowledge. Hence the Semantic Web formalisms need to account for the possibilities that
inductive and abductive inferences offer alongside with the ability to combine ontologies
that, in FOL, would result in inconsistent and hence unusable knowledge.
The discussion about having representations of uncertainty, fuzzy reasoning and con-
tinuous representations in general is less concerned about whether this representation is
necessary, but where it is necessary. Looking at the problems that non-classicallogics pose
to inference mechanisms, the placement has to be done carefully. The easy way out is to
argue that each community that relies on a non-classical representation, does so in their
own ontology with their own agents processing this information. There is a lot of merit to
this argument, but we are going to show that it will not be sufficient in the long run, if the
Semantic Web is to be exploited to its full potential.
In a current scenario, in which we see the mere beginning of the application of Semantic
Web technologies,ontologies tend to be a convenient way of porting database information.
This is a large step by itself, but while it allows machines to read and maybe process data
from multiple sources, it doesn't give us a way of reliably putting derived knowledge from
these multiple sources back on the web. With human intervention, we filter information
that we think wasn't derived in a scientifically viable way and we have the ability to trust
and distrust sources. In most current applications, there is only one step of computational
inference between two tasks accomplished by humans. If now we are trying to have an
automated chain of inference, the agents involved need to tell each other about the confi-
dence they have in the truth of their derived information, which is in turn a function of the
reliability of their sources and their inference methods. An internal procedure, even a very
sophisticated one that allows an agent to filter out information that according to its criteria
does not exceed a certain threshold of reliability will not be of any use, if it propagates the
remaining inferred information as completely reliable information or knowledge.
The Semantic Web has the potential to make an immense impact on human society in
general and on science in particular.The decisions made in the beginning will be difficult
to revise at a later stage. We see, for example, how hard it is to change from a 32 bit IP
=ri as
address to a 128 bit address. For these reasons we need to be careful what we desi,
the foundational formalisms of this Semantic Web. We need to make sure that u.e promote](https://image.slidesharecdn.com/71317-250615103929-fea58a89/85/Fuzzy-Logic-and-the-Semantic-Web-1st-Edition-Elie-Sanchez-Eds-25-320.jpg)
![rejected as too poor for use. Such milk has probably been skimmed,
or comes from unhealthy or poorly fed cows.
The specific gravity of milk should be from 1.027 to 1.033. This
may be found with a Quevenne's lactometer. If it falls below 1.027,
one has a right to claim that the milk has been watered or that the
cows are in poor condition.[16]
The reaction of good milk varies from slightly alkaline to slightly
acid or neutral. That from the same cow will be different on different
days, even under the same apparent conditions of care, varying from
one to the other, probably because of some difference in the nature
of the food she has eaten. However, if the reaction is decidedly
alkaline, and red litmus-paper becomes a distinct blue, the milk is
not good, and possibly the animal is diseased. Should the reaction
be decidedly acid, it shows that the milk has been contaminated,
either from the air by long exposure, or from the vessels which held
it, with those micro-organisms which by their growth produce an
acid, a certain amount of which causes what is known as "souring."
Milk from perfectly healthy and perfectly kept cows is neutral,
leaving both red and blue litmus-paper unchanged; but as a general
thing milk is slightly acid, even when transported directly from the
producer to the consumer and handled by fairly clean workmen in
fairly clean vessels. Such milk two or three hours old when examined
microscopically is found to contain millions of organisms. Milk is one
of the best of foods for bacteria, many of the ordinary forms growing
in it with exceeding rapidity under favorable conditions of
temperature. Now it has been found that such milk, although it may
not contain the seeds of any certain disease, sometimes causes in
young children, and the sick, very serious digestive disturbances,
and may thus become indirectly the cause of fatal maladies.[17]
All milk, unless it is positively known to be given by healthy, well-
nourished animals, and kept in thoroughly cleaned vessels free from
contamination, should be sterilized before using. Often the
organisms found in milk are of disease-giving nature. In Europe and](https://image.slidesharecdn.com/71317-250615103929-fea58a89/85/Fuzzy-Logic-and-the-Semantic-Web-1st-Edition-Elie-Sanchez-Eds-27-320.jpg)
![America many cases of typhoid fever, scarlatina, and diphtheria have
been traced to the milk-supply. In fact milk and water are two of the
most fruitful food sources of disease. It therefore immediately
becomes apparent that, unless these two liquids are above
suspicion, they should be sterilized before using. Boiling water for
half an hour will render it sterile, but milk would be injured by
evaporation and other changes produced in its constituents by such
long exposure to so high a degree of heat. A better method, and one
which should be adopted by all who understand something of the
nature of bacteria, is to expose the milk for a longer time to a lower
temperature than that of boiling.
To Sterilize Milk for Immediate Use. (1) Pour the milk into a
granite-ware saucepan or a double boiler, raise the temperature to
190° Fahr., and keep it at that point for one hour. (2) As soon as
done put it immediately into a pitcher, or other vessel, which has
been thoroughly washed, and boiled in a bath of water, and cool
quickly by placing in a pan of cold or iced water. A chemist's
thermometer, for testing the temperature, may be bought at any
pharmacy for a small sum, but if there is not one at hand, heat the
milk until a scum forms over the top, and then keep it as nearly as
possible at that temperature for one hour. Do not let it boil.
To Sterilize Milk which is not for Immediate Use. Put the
milk into flasks or bottles with narrow mouths; plug them with a long
stopper of cotton-wool, place the flasks in a wire frame to support
them, in a kettle of cold water, heat gradually to 190° Fahr., and
keep it at that temperature for one hour. Repeat this the second day,
for although all organisms were probably destroyed during the first
process, spores which may have escaped will have developed into
bacteria. These will be killed by the second heating. Repeat again on
the third day to destroy any life that may have escaped the first two.
Spores or resting-cells are the germinal cells from which new
bacteria develop, and are capable of surviving a much higher
temperature than the bacteria themselves, as well as desiccation and
severe cold.[18] Some writers give a lower temperature than 190°](https://image.slidesharecdn.com/71317-250615103929-fea58a89/85/Fuzzy-Logic-and-the-Semantic-Web-1st-Edition-Elie-Sanchez-Eds-28-320.jpg)
![Fahr. as safe for sterilization with one hour's exposure, but 190 may
be relied upon. Milk treated by the last or "fractional" method of
sterilization, as it is called, should keep indefinitely, provided of
course the cotton is not disturbed. Cotton-wool or cotton batting in
thick masses acts as a strainer for bacteria, and although air will
enter, organisms will not.
All persons who buy milk, or in any way control milk-supplies,
should consider themselves in duty bound to (1) ascertain by
personal investigation the condition in which the cows are kept. If
there is any suspicion that they are diseased, a veterinary surgeon
should be consulted to decide the case. If they are healthy and well
fed, they cannot fail to give good milk, and nothing more is to be
done except to see that it is transported in perfectly cleansed and
scalded vessels. (2) If it is impossible to obtain milk directly from the
producer, and one is obliged to buy that from unknown sources, it
should be sterilized the moment it enters the house. There is no
other means of being sure that it will not be a bearer of disease. Not
all such milk contains disease-producing organisms, but it all may
contain them, and there is no safety in its use until all bacteria have
been deprived of life.
DIGESTION
Definition. Digestion is the breaking up, changing, and liquefying
of the food in the various chambers of the alimentary canal designed
for that purpose. The mechanical breaking up is done principally by
the teeth in the mouth, the chemical changes and liquefying by the
various digestive fluids.[19]
Digestive Fluids. The digestive fluids are true secretions. Each is
formed from the blood by a special gland for the purpose which
never does anything else; they do not exist in the blood as such.
Their flow is intermittent, taking place only when they are needed.
The liver, however, is an exception to all the others. It is both](https://image.slidesharecdn.com/71317-250615103929-fea58a89/85/Fuzzy-Logic-and-the-Semantic-Web-1st-Edition-Elie-Sanchez-Eds-29-320.jpg)
![secretory and excretory, and bile is formed all the time, but is most
abundant during digestion.[20]
Saliva. The fluid which is mixed with the food in the mouth is
secreted by a considerable number and variety of glands, the
principal of which are the parotid, submaxillary, and sublingual.
Smaller glands in the roof and sides of the mouth, in the tongue,
and in the mucous membrane of the pharynx contribute to the
production of saliva, the digestive fluid of the mouth. The flow from
the parotid gland is greatest. The flow from all the glands is greatly
increased when food is taken, especially if it be of good flavor.
Sometimes the amount is increased by smell alone, as when a nice
steak is cooking, or a savory soup, and sometimes the saliva is made
copious by thought, as when we remember the taste of dishes eaten
in the past, and we say, "It makes the mouth water just to think of
them."
Amount of Saliva. According to Dalton the amount of saliva
secreted every twenty-four hours is 42½ oz. Its reaction is almost
constantly alkaline. It is composed of water, organic matter, and
various mineral salts. Ptyalin is its active principle, and is called by
some authors animal diastase, or starch converter.
Gastric Juice. Gastric juice is the digestive fluid of the stomach.
It is acid. Its flow is intermittent, occurring only at times of
digestion. Its active principle is pepsin.
It is worthy of notice here that the character of the digestive fluids
when food is taken is different from what it is when the organs are
at rest. For instance, the gastric juice which flows in abundance
under the stimulus of food, is not like the fluid secreted when the
stomach is collapsed and empty.
Pancreatic Juice. Pancreatic juice is the digestive juice of the
pancreas, and is poured into the small intestine a short distance
below the pyloric opening. Its reaction is alkaline. Its flow is entirely
suspended during the intervals of digestion.](https://image.slidesharecdn.com/71317-250615103929-fea58a89/85/Fuzzy-Logic-and-the-Semantic-Web-1st-Edition-Elie-Sanchez-Eds-30-320.jpg)
![agreement that it does not change cane-sugar, neither is cane-sugar,
as such, absorbed in the intestine. Bile does not affect it, therefore
cane-sugar is digested or converted into glucose either by the
stomach or pancreas, or both. It will now be seen that ultimately the
same substance, glucose, is obtained from both starch and sugar.
Protein. We now come to the consideration of the digestion of
the protein compounds, of which albumen may be taken as a type.
Possibly no action except breaking up and moistening takes place in
the mouth.[21] Its digestion begins in the stomach, where its
structure is broken up and a separation and dissolution of the little
sacs which hold it take place. The same thing is partially
accomplished outside of the stomach when white of egg is slightly
beaten and strained through a cloth. Gastric juice further acts on the
albumen itself, forming it into what is called albumen peptone. The
digestion of raw and carefully cooked albumen has been found to be
carried on very rapidly in the stomach, and the change is essentially
the same in both cases, but in favor of the slightly coagulated. When
the albumen is rendered hard, fine, and close in consistency by over-
cooking, then it is less easy of digestion than when raw.
Absorption. It is probable that the greater portion of the process
of digestion and absorption of albumen takes place in the stomach.
Fibrin. Fibrin is also digested in the stomach, and made into fibrin
peptone.
Casein. Liquid casein is immediately coagulated by gastric juice,
both by the action of free acid and organic matter.
Gelatin. Gelatin is quickly dissolved by gastric juice, and
afterward no longer has the property of forming jelly on cooling.
Gelatin is more rapidly disposed of than the tissue from which it is
produced.
Vegetable Protein. The digestion of the vegetable protein
compounds, such as the gluten of wheat and the protein of the
various grains, such as corn, oatmeal, etc., is undoubtedly carried on
in the stomach, but they must be well softened and prepared by the](https://image.slidesharecdn.com/71317-250615103929-fea58a89/85/Fuzzy-Logic-and-the-Semantic-Web-1st-Edition-Elie-Sanchez-Eds-32-320.jpg)
![Anything which aids in sustaining the body is food; therefore, air
and water, the two most immediate necessities of life, may be, and
often are, so classed.
Nutriment exclusive of air is received into the body by means of
the alimentary canal. The great receiver of air is the lungs, but it
also penetrates the body through the pores of the skin, and at these
points carbonic acid is given off as in the lungs. The body is often
compared to a steam-engine, which takes in raw material in the
form of fuel and converts it into force or power. Food, drink, and air
are the fuel of the body,—the things consumed; heat, muscular and
intellectual energy, and other forms of power are the products.
Food, during the various digestive processes, becomes reduced to
a liquid, and is then absorbed and conveyed, by different channels
constructed for the purpose, into the blood, which contains, after
being acted upon by the oxygen of the air in the lungs, all those
substances which are required to maintain the various tissues,
secretions, and, in fact, the life of the system.
Some of the ways in which the different kinds of food nourish the
body have been found out by chemists and physiologists from actual
experiments on living animals, such as rabbits, dogs, pigs, sheep,
goats, and horses, and also on man. Often a scientist becomes so
enthusiastic in his search for knowledge about a certain food that he
gives his own body for trial. Much valuable work has been done in
this direction during the last decade by Voit, Pettenkofer, Moleschott,
Ranke, Payen, and in this country by Atwater.
No one can explain all the different intricate changes which a
particle of food undergoes from the moment it enters the mouth
until its final transformation into tissue or some form of energy; but
by comparing the income with the outgo, ideas may be gained of
what goes on in the economy of the body, and of the proportion of
nutrients used, and some of the intricate and complex chemical
changes which the different food principles undergo in the various
processes of digestion, assimilation, and use.[22] Probably hundreds
of changes take place in the body, in its various nutritive functions,](https://image.slidesharecdn.com/71317-250615103929-fea58a89/85/Fuzzy-Logic-and-the-Semantic-Web-1st-Edition-Elie-Sanchez-Eds-34-320.jpg)
![of which nothing is known, or they are entirely unsuspected, so that
if we do our utmost with the present lights which we possess for
guidance to health, we shall still fall far short of completeness. The
subject of food and nutrition, viewed in the light of bacteriology and
chemistry, is one of the most inviting subjects of study of the day,
and is worthy of the wisest thought of the nation.
The body creates nothing of itself, either of material or of energy;
all must come to it from without. Every atom of carbon, hydrogen,
phosphorus, or other elements, every molecule of protein,
carbohydrate, or other compounds of these elements, is brought to
the body with the food and drink it consumes, and the air it
breathes. Like the steam-engine, it uses the material supplied to it.
Its chemical compounds and energy are the compounds and energy
of the food transformed (Atwater). A proof of this is seen in the fact
that when the supply from without is cut off, the body dies. The raw
material which the body uses is the air and food which it consumes,
the greater portion of which is digested and distributed, through the
medium of the blood, to all parts of the body, to renew and nourish
the various tissues and to supply the material for the different
activities of life.
Ways in which Food Supplies the Wants of the Body. Food
supplies the wants of the body in several ways—(1) it is used to
form the tissues of the body—bones, flesh, tendons, skin, and
nerves; (2) it is used to repair the waste of the tissues; (3) it is
stored in the body for future use; (4) it is consumed as fuel to
maintain the constant temperature which the body must always
possess to be in a state of health; (5) it produces muscular and
nervous energy.[23] The amount of energy of the body depends
upon two things—the amount in the food eaten, and the ability of
the body to use it, or free it for use.
With every motion, and every thought and feeling, material is
consumed, hence the more rapid wearing out of persons who do
severe work, and of the nervous—those who are keenly susceptible](https://image.slidesharecdn.com/71317-250615103929-fea58a89/85/Fuzzy-Logic-and-the-Semantic-Web-1st-Edition-Elie-Sanchez-Eds-35-320.jpg)
![structure in the body in which any form of energy is manifested is
nitrogenous. The nerves, muscles, glands, and the floating cells[24]
in the various liquids are nitrogenous. That nitrogen is necessary to
the different processes of the system, is shown by the fact that if it
be cut off, these processes languish. This may not occur
immediately, for the body always has a store of nitrogen laid by for
emergencies which will be consumed first, but it will occur as soon
as these have been consumed. The energy of the body is measured
by its consumption of oxygen. Motion and heat may be owing to the
oxidation of fat, or of starch, or of nitrogenous substances; but
whatever the source, the direction is given by the nitrogenous
structure—in other words, nitrogen is necessary to all energy
generated in the body.
Protein matter nourishes the organic framework, takes part in the
generation of energy, and may be converted into non-nitrogenous
substances.[25] The necessity of the protein compounds is
emphasized when we realize that about one half of the body is
composed of muscle, one fifth of which is protein, and the nitrogen
in this protein can be furnished only by protein, since neither fats
nor carbohydrates contain it. It is therefore evident that the protein-
containing foods, such as beef, mutton, fish, eggs, milk, and others,
are our most valued nutrients. Our daily diet must contain a due
proportion.
The proteins are all complex chemical compounds, which in
nutrition become reduced to simple forms, and are then built up
again into flesh. The animal foods are in the main the best of the
protein compounds, for they are rich in nitrogenous matter, are
easily digested, and from their composition and adaptability are
most valuable in maintaining the life of the body.
A diet of lean meat alone serves to build up tissue. If nothing else
be taken, the stored-up fat of the body will be consumed, and the
person will become thin.[26] Athletes while in training take
advantage of this fact, and are allowed to eat only such food as shall
furnish the greatest amount of strength and muscular energy with a](https://image.slidesharecdn.com/71317-250615103929-fea58a89/85/Fuzzy-Logic-and-the-Semantic-Web-1st-Edition-Elie-Sanchez-Eds-38-320.jpg)
![minimum of fat. The lean of beef and mutton, with a certain amount
of bread, constitute the foundation of the diet.
Fats. Most of the fatty substances of food are liquefied at the
temperature of the body. When eaten in the form of adipose tissue,
as the fat of beef and mutton, the vesicles or cells in which the fat is
held are dissociated or dissolved, the fat is set free, and mingles
with the digesting mass. This is done in the stomach, and is a
preparation for its further change in the intestines.
Fats are not dissolved—that is, in the sense in which meats and
other foods are dissolved—in the process of digestion; the only
change which they undergo is a minute subdivision caused
principally by the action of the pancreatic juice. In this condition of
fine emulsion they are taken up by the lacteals; they may also be
absorbed by the blood-vessels.
It has been found that fat emulsions pass more easily through
membranes which have been moistened with bile, and it is probable
that the function of bile is partly to facilitate the absorption of fat.
That the pancreatic juice is the chief agent in forming fats into
emulsion was discovered in 1848. Bile is, however, essential to their
perfect digestion, and we may therefore say that they are digested
by the united action of the pancreatic juice and the bile.[27]
Fat forms in the body fatty tissues, and serves for muscular force
and heat; it is also necessary to nourish nerves and other tissues,—
in fact, without it healthy tissues cannot be formed. A proper
amount of fat is also a sort of albumen sparer.
It is probable that the fat which is used in the body either to be
stored away or for energy, is derived from other sources than
directly from the fat eaten. From experiments made by Lawes and
Gilbert on pigs, it is evident that the excess of fat stored in their
bodies must be derived from some other source than the fat
contained in their food, and must be produced partly from
nitrogenous matter and partly from carbohydrates, or, at least, that
the latter play a part in its formation. It would appear from this that](https://image.slidesharecdn.com/71317-250615103929-fea58a89/85/Fuzzy-Logic-and-the-Semantic-Web-1st-Edition-Elie-Sanchez-Eds-39-320.jpg)
![life might be maintained on starch, water, salts, and meat free from
fat; but although the theory seems a good one, practically it is found
in actual experiment[28] that nutrition is impaired by a lack of fat in
the diet. The ill effects were soon seen, and immediate relief was
given when fat was added to the food. Besides, in the food of all
nations starch is constantly associated with some form of fat; bread
with butter; potatoes with butter, cream, or gravy; macaroni and
polenta with oil, and so forth. A man may live for a time and be
healthy with a diet of albuminoids, fats, salts, and water, but it has
not yet been proved that a similar result will be produced by a diet
of albuminoids, carbohydrates, salts, and water without fat. Fat is
necessary to perfect nutrition. Health cannot be maintained on
albuminoids, salts, and water alone; but, on the other hand, cannot
be maintained without them.
Probably the value of fats, as such, is dependent upon the ease
with which they are digested. The fats eaten are not stored in the
body directly, but the body constructs its fats from those eaten, and
from other substances in food,—according to some authorities from
the carbohydrates and proteids, and according to others from
proteids alone.
Fats are stored away as fat, furnish heat, and are used for energy;
at least, it is probable that at times they are put to the latter use.
The fats laid by in the body for future use last in cases of starvation
quite a long time, depending, of course, upon the amount. At such
times a fat animal will live longer than a lean one.
Doubtless in the fat of food the body finds material for its fats in
the most easily convertible form. Of the various fatty substances
taken, some are more easily assimilated than others. Dr. Fothergill,
in "The Town Dweller," says that the reason that cod-liver oil is given
to delicate children and invalids is, that it is more easily digested
than ordinary fats, but it is an inferior form of fat; the next most
easily digested is the fat of bacon. When a child can take bread
crumbled in a little of this fat, it will not be necessary to give him
cod-liver oil. Bacon fat is the much better fat for building tissues.](https://image.slidesharecdn.com/71317-250615103929-fea58a89/85/Fuzzy-Logic-and-the-Semantic-Web-1st-Edition-Elie-Sanchez-Eds-40-320.jpg)
![Water is found in all parts of the body, even in the very solid
portions, as the bones and the enamel of the teeth; it also
constitutes a large proportion of its semisolids and fluids, some of
which are nearly all water, as the perspiration and the tears.
Water usually is found combined with some of the salts, which
seem to act as regulators of the amount which shall be incorporated
into a tissue. Water is a necessary constituent of all tissues, giving
them a proper consistency and elasticity. The power of resistance of
the bones could not be maintained without it. It is also valuable as a
food solvent, assisting in the liquefying of different substances,
which are taken up by the various absorbent tubes, conveyed into
the blood, and so circulated through the body. Most of the water of
the body is taken into it from without, but it is also formed in the
body by the union of hydrogen and oxygen.[29]
Sodium chlorid, or common salt, is found in the blood and other
fluids, and in the solids of the body, except the enamel of the teeth;
it occurs in greatest proportion in the fluids. The part that this salt
plays in nutrition is not altogether understood. "Common salt is
intermediate in certain general processes, and does not participate
by its elements in the formation of organs" (Liebig). Salt is intimately
associated with water, which plays an intermediate part also in
nutrition, being a bearer or carrier of nutritious matters through the
body.
Salt seems to regulate the absorption and use of nutrients. It is
found in the greatest quantity in the blood and chyle. It doubtless
facilitates digestion by rendering foods more savory, and thus
causing the digestive juices to flow more freely. Sodium chlorid is
contained in most if not all kinds of food, but not in sufficient
quantity to supply the wants of the body; it therefore becomes a
necessary part of a diet.
Potassium chlorid has similar uses to sodium chlorid, although not
so generally distributed through the body. It is found in muscle, liver,
milk, chyle, blood, mucus, saliva, bile, gastric juice, and one or two
other fluids.](https://image.slidesharecdn.com/71317-250615103929-fea58a89/85/Fuzzy-Logic-and-the-Semantic-Web-1st-Edition-Elie-Sanchez-Eds-43-320.jpg)
![Calcium phosphate is found in all the fluids and solids of the body,
held in solution in them by the presence of CO2; both it and calcium
carbonate enter largely into the structure of the bones.
Sodium carbonate, magnesium phosphate, and other salts play
important parts in nutrition.
The various salts influence chemical change as well as act in
rendering food soluble. For example, serum albumen, the chief
proteid of the blood, is insoluble in pure water, but dissolves easily in
water which has a little neutral salts in it.[30] Salts also help to give
firmness to the teeth and bones.
To recapitulate, food is eaten, digested, assimilated, and
consumed or transformed in the body by a series of highly intricate
and complex processes. It is for the most part used for the different
powers and activities of the system; there is, however, always a
small portion which is rejected as waste. The first change is in the
mouth, where the food is broken up and moistened and the
digestion of starch begins; these changes continue in the stomach
until the whole is reduced to a more or less liquid mass. As the
contents of the stomach pass little by little into the duodenum, the
mass becomes more fluid by the admixture of bile, pancreatic juice,
and intestinal juice, and, as it passes along, absorption takes place;
the mass grows darker in color and less fluid, until all good material
is taken up and only waste left, which is rejected from the body.
That portion of the food which is not affected by the single or
united action of the digestive fluids is chiefly of vegetable origin.
Hard seeds, such as corn, and the outer coverings of grains, such as
the husk of oatmeal and those parts which are composed largely of
cellulose, pass through the intestinal canal without change.
It may be remarked here that since the digestive mechanism is so
perfect a structure, and will try to dissolve anything given it, and
select only that which is good, why should there be the necessity of
giving any special attention to preparing food before it is eaten? The
answer is that the absorptive vessels cannot take up what is not](https://image.slidesharecdn.com/71317-250615103929-fea58a89/85/Fuzzy-Logic-and-the-Semantic-Web-1st-Edition-Elie-Sanchez-Eds-44-320.jpg)
Fuzzy Logic and the Semantic Web 1st Edition Elie Sanchez (Eds.)
- 1. Fuzzy Logic and the Semantic Web 1st Edition Elie Sanchez (Eds.) download pdf https://ebookultra.com/download/fuzzy-logic-and-the-semantic-web-1st- edition-elie-sanchez-eds/ Visit ebookultra.com today to download the complete set of ebook or textbook!
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- 5. Fuzzy Logic and the Semantic Web 1st Edition Elie Sanchez (Eds.) Digital Instant Download Author(s): Elie Sanchez (Eds.) ISBN(s): 9780444519481 Edition: 1 File Details: PDF, 12.12 MB Year: 2006 Language: english
- 9. Preface It is with great delight that I write the preface for this, the very first volume in Elsevier's new book series "Capturing Intelligence". This series aims at publishing books on research from all disciplines dealing with and affecting the issue of understanding and reproducing intelligent artificial systems. The se- ries will cast its net wide, aiming for contributions from diverse areas such as symbolic AI, biological approaches, self-organisation and emergence, and physically embodied systems. Symbolic knowledge representation has a long tradition in the quest to understand the notion of "intelligence", and it is fitting that the first book in our series is rooted in this tradition. However, the current volume is not simply a treatise on classical topics. Instead, it confronts a classical, rich and well-established area, namely the representation of fuzzy, non-crisp concepts, with a new and highly exciting challenge, namely the vision of the Semantic Web. The vision of a more Semantic Web has been attracting much attention by scientists and industrialists alike since early publications on the topic, notably Tim Berners-Lee's book "Weaving the Web" and his Scientific American publication jointly with Jim Hendler and Ora Lasilla in 2001. Higher precision of search engines, searching with semantic instead of syntactic queries, information integration among different web-resources, personalisation, and semantic web services, are all part of the promises of this vision. The insight that any realistic approach to the Semantic Web will have to take into account the lessons from fuzzy logic approaches is gaining ground in a wide community, andslowly but surely, the Semantic Web community is waking up to this fact. For this reason, the current volume is extremely timely. The different papers in this book propose a number of ways in which current Semantic Web technology can be "fuzzified", and they discuss a number of ways in which such fuzzy representations can be used for tasks such as search and information retrieval. I am convinced that this book is a very good and timely start of this new book series, and I am lookingforward to future volumes in this series, of equally high quality and relevance. Frank van Harmelen (Series Editor) vii
- 11. Foreword Fuzzy Logic in the Semantic Web: Coveringa Missing Link 1. Introduction During recent years, important initiatives have led to reports of connections between Fuzzy Logic and the Internet. For example, at the initiative of Lotfi Zadeh and Masoud Nikravesh, FLINT meetings ("Fuzzy Logic and the Internet") have been organized by BISC ("Berke- ley Initiative in Soft Computing"). The proceedings of the FLINT 2001 workshop [I] and of the NAFIPS-FLINT2002 Joint International conference [2] have been published. Mean- while, scattered papers were published on Fuzzy Logic and the Semantic Web. A special session, "Fuzzy Logic in the Semantic Web, a New Challenge", was organized during the IPMU 2004 conference, at Perugia, Italy [3]. The idea for the present book came from en- thusiastic authors and participants at that well-attended session, including: Trevor Martin, Ernesto Damiani, Umberto Straccia and Henrik Legind Larsen. More recently, in Febru- ary 2005, the first workshop on Fuzzy Logic and the Semantic Web [4] at Marseille was attended by European experts in the field (they are all contributors to this book, too). This volume, the first in the new series Capturing Intelligence, shows the positive role Fuzzy Logic, and more generally Soft Computing, can play in the development of the Seman- tic Web, filling a gap and facing a new challenge. It covers concepts, tools, techniques and applications exhibiting the usefulness, and the necessity, of using Fuzzy Logic in the Semantic Web. 2. The Semantic Web and Fuzzy Logic Most of today's Web content is suitable for human consumption. The Semantic Web is presented as an extension of the current web in which information is given well-defined meaning, better enabling computers and people to work in cooperation. For example, within the Semantic Web, computers will understand the meaning of semantic data on a web page by following links to specified ontologies. But while the vision of the Semantic Web and associated research attracts attention, as long as two-value-based logical methods
- 12. are used. no progress can be expected in handling ill-structured, uncertain or imprecise information encountered in real world knowledge. It is also worth noting that Fuzzy Logic (in a simple form) is used in almost all major search engines. Fuzzy Logic will not be the basis for the Semantic Web but its related concepts and techniques will certainly reinforce the systems classically developed within W3C. In fact, Fuzzy Logic cannot be ignored if we are to bridge the gap between human-understandable so8 logic and machine-readable hard logic. None of the usual logical requirements can be guaranteed: there is no centrally defined format for data, no guarantee of truth for assertions made, no guarantee of consis- tency. To support these arguments, this book shows how components of the Semantic Web (such as XML, RDF, OWL, Description Logics, Conceptual Graphs, Ontologies) can be covered, with in each case a Fuzzy Logic focus. The Semantic Web, as presented under W3C recommendations, deals with hard seman- tics in the description and manipulation of crisp data. RDF based languages do not have the ability to represent soft semantics. The Semantic Web allows relational knowledge to be embedded as metadata in web pages enabling machines to use ontologies and inference rules in retrieving and manipulating data. Ontologies bridge an effective communication gap between users and machines. The construction of ontologies is crucial in the develop- ment of the Scientific Web. The key ingredients to build up an ontology are a vocabulary of basic terms and, when possible, a precise specification of the meaning of these terms. In fact. computers require precise definitions but humans normally work better without precise definitions and, mostly due to the nature of the information in world knowledge, there is a need for a collection of tools drawn from Fuzzy Logic, for example Zadeh's PNL (Precisiated Natural Language). A Fuzzy Ontology structure can be defined as consisting of concepts, of fuzzy relations among concepts, of a concept hierarchy or taxonomy, and of a set of ontology axioms, expressed in an appropriate logical language. Then, a lexicon for a fuzzy ontology can consist of lexical entries for concepts (knowledge about them can be given by fuzzy attributes, with context-dependent values), of lexical entries for fuzzy relations, coupled with weights expressing the strength of associations, and of reference functions linking lexical entries to concepts or relations they refer to. DLs (Description Logics) are a logical reconstruction of frame-based knowledge representation languages that can be used to represent the knowledge of an application domain in a structured and formally well-understood way.They are considered as a good compromise between expres- sive power and computational complexity. DLs are essentially the theoreticalcounterpart of the Web Ontology Language OWL DL, the state of the art language to specify ontologies. DLs can be used to define, integrate and maintain ontologies. DLs have been extended with fuzzy capabilities, yielding FDLs (Fuzzy Description Logics) in which concepts are inter- preted as fuzzy sets. These are only a few examples of using Fuzzy Logic in the Semantic Web and many more extended developments are presented in this volume. 3. Structureof the book The book covers such different topics as overviews, proposals for language definitions, on- tology construction, information retrieval and search. It is composed of seven sections. These sections do not constitute a crisp partition. There is some overlap between the chapters (multiple introductions to RDF, OWL, protoforms, etc.). However, this makes the chapters readable independently. Our grouping of chapters was a choice among many
- 13. Foreword xi other possible ones, a choice to give the book more structure for the reader and to make the material more easily accessible. The first section, Introduction, starts with the chapter "On the Expressiveness of the Languages for the Semantic Web - Making a Case for 'A Little More' " by Chnstopher Thomas and Arnit Sheth. It introduces the need for fuzzy-probabilistic formalisms on the Semantic Web, in particular within OWL. It is followed by the chapter "Fuzzy Ontologies for Information Retrieval on the WWW" by David Pany, which deals with the concept of fuzzy ontology, and presents a broad survey of relevant techniques, leading up to the no- tions of fuzzy search and fuzzy ontologies. The third chapter "Capturing Basic Semantics Exploiting RDF-oriented Classification"by Vincenzo Loia and Sabrina Senatore, presents a system designed to support searchingand indexing tools oriented towards semantic-based informationdiscovery.It proposes a semantic RDF-oriented classification of documents to characterize relationships between concepts and web resources. The second section, Fuzzy Description Logics for Ontology Construction, deals with fuzzy description logics in theoretical aspects and applications. The first chapter is "A Fuzzy Description Logic for the Semantic Web" by Umberto Straccia. It describes a fuzzy version of SHOIN(D), the corresponding Description Logic of the ontology description language OWL DL, showing that its representation and reasoning capabilities go clearly beyond classical SHOIN(D).The next chapter "What Does Mathematical Fuzzy Logic Of- fer to Description Logic?" by Petr Hijek, begins with a survey on continuous t-norm based fuzzy predicate logic. Then, it proposes a fuzzy description logic based on fuzzy predicate logic, to deal with vague (imprecise) concepts. The following chapter "Possibilistic Un- certainty and Fuzzy Features in Description Logic. A Preliminary Discussion" by Didier Dubois, JCr8me Mengin, and Henri Prade, is another approach to injecting fuzzy features in Description Logics, this time based on fuzzy and possibilistic logic. The chapter "Un- certainty and Description Logic Programs over Lattices" by Umberto Straccia, presents a Description Logic framework for the management of uncertain information. In this ap- proach, sentences are certain to some degree, where certainty values are taken from a certainty lattice. The last chapter of this section, "Fuzzy Quantification in Fuzzy Desciip- tion Logics", by Daniel Sanchez and Andrea Tettamanzi, introduces reasoning procedures for a fuzzy description logic with fuzzy quantifiers. The third section, Searchand Protofonns,contains chapters with concepts introduced in "From Search Engines to Question Answering Systems - The Problems of World Knowl- edge, Relevance, Deduction and Precisiation", by Lotfi A. Zadeh. This chapter deals with question-answeringsystems - systems with deduction capabilities - with perception-based information, and especially perceptions of probabilities, which are intrinsically imprecise. It introduces and discusses new tools to deal effectively with world knowledge, relevance, deduction and precisiation. These tools, drawn from fuzzy logic, are: Precisiated Natural Language (PNL), Protoform Theory (PFT), and the Generalized Theory of Uncertainty (GTU).The followingchapter, "A Perception-basedSearch with Fuzzy Semantic"by Chris Tseng and Toan Vu, is a proposal for a perception-based search methodology established on fuzzy semantic for improving the websearch. It contains an implementation and case- study in the search domain of health and food. Finally, the chapter "Using Knowledge Trees for Semantic Web Querying" by Ronald Yager, proposes a formalism, involving knowledge trees, for querying the web. Protoforms are also discussed to aid in deduction and manipulation of knowledge.
- 14. xii Forc.tr.o~-(i The fourth section, XML based Approaches, B~lildingOntologies, and (Conceprllal) G1-opl1s. starts with the chapter "Fuzzy Data Mining for the Semantic Web: Building XML Mediator Schemas" by A.Laurent, P. Poncelet and M. Teisseire. It considers the problem of mining XML mediator schemas from a database perspective. XML documents are modeled by labeled ordered trees, Fuzzy Tree Inclusion is addressed and it is proposed to extend the knowledge on the mined semantic structures by providing fuzzy links within frequent trees. Then the chapter "Bottom-up Extraction and Maintenance of Ontology-based Metadata" by Paolo Ceravolo, Angelo Corallo, Ernesto Damiani, Gianluca Elia, Marco Viviani and Antonio Zilli, presents an approach to build fuzzy ontologies in a bottom-up fashion, by clustering documents, based on a fuzzy representation of XML documents structure and content. This section ends with the chapter "Approximate Knowledge Graph Retrieval: Measures and Realization" by T.H. Cao and Dat T. Huynh. It is a proposal for degrees of subsumption, and an engineering work on top of well-established Semantic Web infrastruc- ture software (Sesame). Conceptual graphs are employed for a user-friendly interface and easily readable query expressions. The fifth section, Integration and Processing of Fuzzy Znformation, begins with the chapter "Soft Integration of Information with Semantic Gaps" by Trevor Martin and Ben Azvine. The work aims to identify sources of information referring to a same entity, en- abling merging attributes and integrating attributes to provide a fused information source. Then, the chapter "Processing Fuzzy Information in Semantic Web Applications" by Se- bastian Kloeckner, Klaus Turowski and Uwe Weng, is a discussion on several approaches for processing fuzzy information, to improve the actual concepts of the semantic web. Fi- nally, the chapter "Fuzzy Logic Aggregation for Semantic Web Search for the Best (Top-k) Answers" by Peter VojtiS, presents an application to find best (top-k) answers depending on scoring multicriterial user requirements on the web. The sixth section, Ontologies, Information Retrieval, starts with " A Fuzzy Logic Ap- proach to Information Retrieval using an Ontology-based Representation of Documents", by Mustapha Baziz, Mohand Boughanem, Gabriella Pasi and Henri Prade. This chapter is related to Information Retrieval using fuzzy ontologies and it includes a benchmark eval- uation. It is followed by the chapter "Towards a Semantic Portal for Oncology using a Description Logic with Fuzzy Concrete Domains" by Mathieu dlAquin, Jean Lieber and Amedeo Napoli. It is a work on encoding medical guidelines in fuzzy description log- ics and using that for a portal. The three systems that are presented are fully implemented (KASMIR oncology project). The last chapter of this section,"Fuzzy Relational Oncolog- ical Model in Information Search Systems" by Rachel Pereira, Ivan Ricarte and Fernando Gomide. is another approach to Information Retrieval using fuzzy ontologies encoded by fuzzy relations, with a test case on scientific articles about 'Computational Intelligence'. The last and seventh section, Soft Comp~lting in Various Domains, starts with the chap- ter "Evolving Ontologies for Intelligent Decision Support', by Paulo Gottgtroy, Nikola Kasabov and Stephen MacDonell. It integrates soft computing techniques and ontology engineering. It deals with the rather different (but important) topic of evolving ontologies and it presents biomedical case studies. Finally, the chapter "Enhancing the Power of the Internet using Fuzzy Logic-based Web Intelligence: Beyond the Semantic Web" by Ma- soud Nikravesh, proposes the notion of "Concept-based Databases for Intelligent Decision Analysis" and it discusses several soft computing concepts and tools to search the web.
- 15. Foreword 4. Concluding thoughts These are exciting times in the fields of Fuzzy Logic and the Semantic Web, and this book will add to the excitement, as it is the first volume to focus on the growing connec- tions between these two fields. This book will be a valuable aid to anyone considering the application of Fuzzy Logic to the Semantic Web, because it contains a number of detailed accounts of these combined fields,written by leading authors in several countries. The field of Fuzzy Logic has been maturing for forty years. These years have witnessed a tremen- dous growth in the number and variety of applications, with a real-world impact across a wide variety of domains with humanlike behavior and reasoning. And we believe that in the coming years, the Semantic Web will be a major field of applications of Fuzzy Logic. Paraphrasing Lo@ A. Zadeh [5], we can say that "in moving further into the age of ma- chine intelligerlceand automated reasoning, we have reached a point where we can speak, without exaggeration, of systems which have a high macl~ineIQ (MIQ)... In the context of the Sernalztic Web, MlQ becomes Semantic Web IQ, or SWlQ, for short" References [I] "New Directions in Enhancing the Power of the Internet" (Proceedings UCBIERL, Berkeley, Memo No M01128, August 2001) and "Enhancing the Power of the Internet", M. Nikravesh, B. Azvine, R. Yager, L.A. Zadeh (Eds.),Springer-Verlag, 2004. [2] NAFIPS-FLINT 2002 Int. Conf., IEEE SMC Proceedings 02TH8622, New-Orleans, 2002. [3] IPMU 2004, Special Session "Fuzzy Logic in the Semantic Web: a New Challenge", IPMUOlk3dipmat. unipgit, Perugia, Italy, 2004, Proceedings, pp. 1017-1038. [4] "Fuzzy Logic and the Semantic Web" Workshop, Extended abstracts available at http://waw.lif.univ- rnrs.fr/FLSW, Marseille, France, 2005. [5] L.A. Zadeh, "Web Intelligence and Fuzzy Logic - The concept of Web IQ (WIQ)", Invited talk at the 2003 IEEEMC Int. Conference on Web Intelligence (WI 2003), Halifax, Canada, available at n-ww.comp. hkbu.edu.hkllAT03/InvitedTalkl .htm. Acknowledgements I would like to take this opportunity to give special thanks to all the contributors and also the reviewers for their commitment, hard work and time spent writing the variouschapters. Without their efforts, this volume could not have come to fruition. Elie Sanchez Laboratoire d'Infonnatique Fondamentale BiomathCmatiqueset Informatique 3ICdicale FacultC de MCdecine, UniversitCde la MCditerranke Marseille. France September 2005
- 17. Contents Preface Frank van Harinelen Foreword Elie Sanchez vii 1 Introduction 1. On the Expressivenessof the Languages for the Semantic Web- Making a Case for 'A Little More' 3 Christopher Thonzas and Ainit Slzeth 2. Fuzzy Ontologies for Information Retrieval on the WWW 21 David Parry 3. Capturing Basic Semantics Exploiting RDF-oriented Classification 49 VincenzoLoia and Sabrilza Senatore Fuzzy Description Logics for Ontology Construction 71 4. A Fuzzy Description Logic for the Semantic Web 73 Umber.toStraccia 5. What Does Mathematical Fuzzy Logic Offer to Description Logic? 91 Petr Hcijek 6. Possibilistic Uncertainty and Fuzzy Features in Description Logic. A Prelirni- nary Discussion 101 Didier Dubois, Je'r6nze Mengin and Henri Prude 7. Uncertainty and Description Logic Programs over Lattices 115 UmbertoStraccia f! 135 8. Fuzzy Quantification in Fuzzy Description Logics Daniel Scinchez and Andrea G.B. Tettanzanzi Searchand Protoforms 161 9. From Search Engines to Question Answering Systems -TheProblems of World Knowledge, Relevance, Deduction and Precisiation 163 Lo@ A. Zndeh 10. A Perception-based Web Search wit11 Fuzzy Semantic 211 Chris Tseitg and Toan Vu 11. Using Knowledge Trees for Semantic Web Querying 231 Ronald R. Yager
- 18. xvi COII tents XhIL based Approaches, Building Ontologies, and (Conceptual) Graphs 247 12. Fuzzy Data Mining for the Semantic Web: Building XML Mediator Schemas 249 A. Lctlrrent, M. Teisseire and I? Poncelet 13. Bottom-up Extraction and Maintenance of Ontology-based Metadata 265 Paolo Ceravolo, Angelo Corallo, Ernesto Dainiani, Gianluca Elia, hlrrrcoWviani and Antonio Zilli 14. Approximate Knowledge Graph Retrieval: Measures and Realization 283 T.H. Cao and Dat T. Huynh Integration of Processing of Fuzzy Information 305 15. Soft Integration of Information with Semantic Gaps 307 Traor Martin and Ben Azvine 16. Processing Fuzzy Information in Semantic Web Applications 327 Sebastian Kloeckner; Kla~ts Turowski and Uwe Weng 17. Fuzzy Logic Aggregation for Semantic Web Search for the Best (Top-k) Answer 341 Peter VojtdS Ontologies, Information Retrieval 361 18. A Fuzzy Logic Approach to Information Retrieval Using an Ontology-based Representation of Documents 363 Mzrsrrrpha Baziz, Mohand Boughanem, Henr-i Prade and Gabriella Pasi 19. Towards a Semantic Portal for Oncology Using a Description Logic with Fuzzy Concrete Domains 379 klrrti~ie~i dlAquin,Jean Lieber and Amedeo Napoli 20. Fuzzy Relational Ontological Model in Information Search Systems 395 Rachel Pereira, Ivan Ricarte and Fernando Gonzide Soft Computing in Various Domains 413 21. Evolving Ontologies for Intelligent Decision Support 415 Pmtlo Gottgrroy, Nikola Krrsabov and Stephen MacDonell 22. Enhancing the Power of the Internet Using Fuzzy Logic-based Web Intelligence: Beyond the Semantic Web 441 hlrrsoud Nikravesh Author Index Subject Index
- 19. Introduction 1. On the Expressiveness of the Languages for the Semantic Web - Making a Case for 'A Little More' Christopher Thomas and Amit Sheth 2. Fuzzy Ontologiesfor Information Retrieval on the WWW David Parry 3. Capturing Basic SemanticsExploiting RDF-orientedClassification VincenzoLoia and Sabrina Senatore
- 21. CHAPTER 1 On the Expressivenessof the Languages for the Semantic Web -Making a Case for 'A Little More' Christopher Thomas and Amit ~heth* Large Scale Distributed Information Systenzs Lab, Unir~ersily of Georgia, Athens, GA, USA E-mail: chaos@uga.edu: amit@cs.uga.edu Abstract The best pair of shoes you can find are the ones that fit perfectly. No inch too short, no inch too wide or long. The same, of course, holds for applications in all fields of computer science. It should serve our needs perfectly. If it does more, it usually comes with a tradeoff in performance or scalability. On top of that, for logic based systems, the maintenance of a consistent knowledge base is important. Hence a decidable language is needed to maintain this consistency computationally. Recently, the restriction of the Semantic Web standard OWL to bivalent logic has been increasingly criticized for its inability to semantically express uncertainties. We will argue for the augmentation of the current standard to close this gap. We will argue for an increased expressiveness at different layers of the cake and we want to show that only a spiced up version of some of the layers can take the blandness out of it. We want to show that it is possible to havea mixture thatcan account for reasoning based on uncertainties, possibilistic measures, but also for other epistemologically relevant concepts, such as belief or trust. Keywords semantic web, fuzzy logic, probability theory, knowledge representation "SO far as the laws of mathematics refer to reality, they are not certain. And so far as they are certain, they do not refer to reality." Albert Einstein * Corresponding author. FUZZY LOGIC AND THE SEMANTIC WEB Edited by Elie Sanchez 02006 Elsevier B.V. All rights reserved
- 22. 1. Introduction During the 2004 WWW conference, Tim Berners-Lee, the spiritual leader of the semantic web community, made a statement that might impact further research on semantic web foundations. Asked whether it is necessary to have a representation for uncertainty on the layered semantic web stack, his answer was basically "no". Knowing about the impact of a person like Berners-Lee, this view might have great impact on the community and hence on unfortunate students and researchers funded for the development of uncertainty calculi for the semantic web. But aside from personal considerations, this answer can be challenged on many levels. After all, history has shown many times that "the revolution eats its children". When talking about extending the kinds of logical inference used in local or global knowledge bases, we have to be aware of the different ways in which this can be done. The semantic web standard assumes a monotonic bivalent logic. Bivalent means that state- ments are either true or false; no third possibility, such as unknown, exists, nor anything in between true and false. In the remainder of the paper we will refer to these bivalent logics as FOL (first-order logics). Research in logic has produced a plethora of different formalisms which are more or less used in real-world applications. There are many-valued logics, continuous-valued logics with different semantics of their value assignments, such as fuzzy logics and probabilis- tic logics [13,15], non-monotonic logics [38], paraconsistent logics [5] and combinations thereof [lo]. One can make a case for the use of any of these logics for different applica- tions. The question for semantic web researchers is, whether to augment the famous layer cake by adding a different layer for non-bivalent and/or non-monotonic logics or whether these ausmentations should exist locally, for groups of agents that agree to their own rep- resentation of non-FOL statements. Berners-Lee's main argument for the rejection of a representation of uncertainty at the very basis of Semantic Web formalisms was their lacking scalability. This is a strong argu- ment. For example, in order to do complete probabilistic inference on dependent objects in a Bayesian Network or any other technology for probabilistic inference, potentially every path through the network has to be taken into account. The same holds for any kind of non-monotonic logic. Given that, even in the case of FOL, such as SHIQ [18] or similar Description logics, inference cannot be done in a computationally efficient way, it seems mandatory to keep the evaluation of statements local. One major problem that monotonic knowledge bases face is that of inconsistency. In a monotonic logic, such as each of the various flavors of bivalent Description Logics and hence OWL, it is assumed that if a true statement can be derived from a set S of facts and rules, then it can also be derived from every larger set Sf that contains S. This is an appealins assumption to make, because it allows reasoning to be local and to only take into account the rules and facts that are immediately necessary to deduce a new statement. But it is also an unrealistic assumption to make, because the world, even the formalized one, is full of contradictions. And the more this world of formal statements grows, the more likely it i$ that a contradiction occurs. For this reason, the CYC@Ontology is partitioned into consistent micro theories or contexts [311. Inconsistencies with other micro theories are explicitly stated. To give an example of how easily inconsistencies can occur when we get to know more about a domain, we cite an example that is widely used in A1 textbooks. It involves birds. We will state the knowledge base informally:
- 23. On the expressiveness o f tl~e lang~tages for !he sernantic web - Birds fly (Vx: bird(x) -+ fly(x)) - Penguins are birds (Vx: penguin(x) -+ bird(.u)) - Joe is a penguin (penguin(Joe)) We can deduce now, that Joe is a bird and hence can fly. But there's one more rule that. for the sake of accuracy, could be added to the domain representation. - Penguins don't fly (Vx: penguin(x) -+ -fly(x)) This statement causes an inconsistency in the knowledge base. If we follow the path Joe is a penguin, penguins are birds, birds fly, then Joe flies. If we follow the path Joe is a penguin, penguins don't fly, then Joe doesn't. The addition of a rule made the knowledge base inconsistent, even though it was a sensible rule to add. And locally, the knowledge base was also correct before this rule was added. It was just missing some information and it still is missing information. Complete formalized knowledge of a domain is an illusion. It is no question that inconsistencies arise when combining knowledge from multiple sources. It is also no question that most real-world phenomena cannot be sufficiently de- scribed in a bivalent logic. This holds in two cases. We can look at this from a scientific point of view, where we have to deal with uncertainty, randomness and partial knowledge. In this case even extremely accurate measurements result in uncertainties about the im- plications of the obtained data. The second case is that of knowledge representation and computation based on human perception as described in 1401. Here, non-bivalence and inconsistencies occur because of a fundamental inability to conduct completely accurate measurements on the one hand but the corresponding human ability to accurately reason with this inaccurate knowledge. The question for the Semantic Web research is. though, whether the basis of Semantic Web standards should be the bivalent monotonic case and the uncertain and/or non-monotonic cases are a specialization thereof, or whether the basis should be the uncertain case with bivalent monotonic logics as a special case. 1.1. Science In essence, it is also a question about the extent to which the use of ontologies will have an impact on how humans gain and evaluate knowledge. The time we are living in is partially signified by the specialization of the scientific fields. The time in which an Aristotle could have all scientific knowledge of his cultural realm is long gone. It is even impossible to know about all current developments in adjacent fields. Over time, science evolved into a hydra who's heads are autonomous and quite ignorant about what happens in most of it's other heads, a giant distributed apparatus that is striving towards progress without the ability to take a comprehensive snapshot of the current state. Hypotheses are generated, but are mostly evaluated against the knowledge of a small field. A formalization of these hypotheses could allow the scientific communities to extensively evaluate their findings. Agents could roam the web and cross check hypotheses with data obtained by other labs and compare the results and hypotheses generated from the data to find similarities and contradictions. In a scientific environment or in general in fields that are mainly driven by empirically closing the gaps of incomplete knowledge of their domain, it is necessary that the knowl- edge bearing agent is aware of the partiality of its knowledge. In a localized system, that is easily accomplished. If we want to share information across the Internet, then the fom~al- ism that encapsulates this knowledge needs to reflect this partiality, so it can be propagated to other agents. Otherwise it is like telling rumors. I heard from my not very trustworthy
- 24. 6 Clr. Tf~ort~ns orld A. Sherh acquaintance Paul that Peter and Mary broke up recently. While I might still have propa- gated it as a rumor that I did not really trust to Cathy, she might have told it as a fact to Marc u ho was Peter's best friend but always had his eyes on Mary. After asking her out on a date. his Friendship with Peter was shattered. If every link in this gossip chain had kept the information that it was just a rumor, Marc and Peter would be drinking beer now. 1.2. Itlfomation retrieval In information retrieval, we are dealing with all sorts of noisy data. Web search engines and proposed question answering systems that are based on information available on the Internet or in local ontologies will on average yield results that are not totally relevant or reliable. The annotation of data with metadata will improve this situation, but not funda- mentally change it. Hence, an estimate of relevance or truth, delivered together with the answer or answer set, would be desirable. Recently, more statistical techniques have emerged in Internet search engines. While Google's page rank [8] measures the popularity of a page and makes the implicit assump- tion that popularity is somewhat linked to importance, other search engines use clustering to order their search results. The Vivisimo search engine [42] builds a hierarchy for the search results using a hierarchical clustering technique. The Vivisimo approach is only the first of many search engines that give a hierarchical structure of their search results. We will also encounter situations in which we want to build ontologies or topic maps on the fly from sets of documents that have not yet been classified' [21,29]. Any automatic approach to ontology generation, be it statistical, using pattern based, NLP or other techniques, must be uncertain in nature and the map must reflect its own uncertainty about the inferred knowledge. In the Semantic Web context, this uncertainty cannot just be stored within the generating or retrieving agent, but must be propagated through the deductions or other reasoning steps that are performed with the information. In a future situation, when a derived fact is anno- tated with the trace of its derivation (i.e. its provenance information), this will become clear. In community based knowledge accumulation, such as an augmented "Semantic Wikipedia" project [41], the community could assign degrees of belief to the formalized facts. Each agent in turn can assign degrees of belief to selected ontologies or single facts within ontologies. The latter is an individual assignment and doesn't require a formaliza- tion, but the former needs to be made available to general purpose reasoners, if we want the Semantic Web vision of connectivity between heterogeneous knowledge sources become a reality. For the next generation of web search engines, question answering machines, it will be crucial to have a powerful representation of vagueness, because the terms humans use to describe the world will be vague and ambiguous [28,30,40]. 1.3. Sev~antic Web Semantic heterogeneity is an inherent reality of the Internet. It is possible to encompass all types of syntactic, schematic and semantic heterogeneity that have been discussed in I The term ontology usually implies a rigid knowledge representation which meets formal criteria of inheritance or soundness/completeness issues. The tenn topic map has a less formal connotation.
- 25. On !he expresshvness of rhe languagesfor rhe ser?ranricweb 7 research on heterogeneous databases [22,24,33].This diversity makes it the most useful, ubiquitous and unbiased collection of knowledge that has ever existed. The challenge to a computational use of this smorgasbord of opinions is to keep the diversity while still having a sound basis for computation. Inability of first order to model heterogeneity even in relational databases was conclusively discussed [26]. In the real world realization of the Semantic Web, very few ontologies will be consistent with each other. These inconsisten- cies can arise for multiple reasons. The easiest resolution is that of ambiguity in terns and actual formalization while still agreeing on the conceptualization as such. But ontologies can also be fundamentally inconsistent, because the ontological and metaphysical basis is different, i.e. the ontologies don't share the same view of the world or their domain, or the factual knowledge used to populate them come from different sources whose observations are inconsistent with each other. This paperis meant to show that,despite computational disadvantages, many signs point b- towards incorporating the representation of more powerful semantics into the Semantic Web layer cake. While it is computationally impossible to logically track every statement on the web and use it in every logical inference, a restriction to deduction within local on- tologiesbased on FOL will only exploit the local knowledge, but never help acquiring new knowledge. Hence the Semantic Web formalisms need to account for the possibilities that inductive and abductive inferences offer alongside with the ability to combine ontologies that, in FOL, would result in inconsistent and hence unusable knowledge. The discussion about having representations of uncertainty, fuzzy reasoning and con- tinuous representations in general is less concerned about whether this representation is necessary, but where it is necessary. Looking at the problems that non-classicallogics pose to inference mechanisms, the placement has to be done carefully. The easy way out is to argue that each community that relies on a non-classical representation, does so in their own ontology with their own agents processing this information. There is a lot of merit to this argument, but we are going to show that it will not be sufficient in the long run, if the Semantic Web is to be exploited to its full potential. In a current scenario, in which we see the mere beginning of the application of Semantic Web technologies,ontologies tend to be a convenient way of porting database information. This is a large step by itself, but while it allows machines to read and maybe process data from multiple sources, it doesn't give us a way of reliably putting derived knowledge from these multiple sources back on the web. With human intervention, we filter information that we think wasn't derived in a scientifically viable way and we have the ability to trust and distrust sources. In most current applications, there is only one step of computational inference between two tasks accomplished by humans. If now we are trying to have an automated chain of inference, the agents involved need to tell each other about the confi- dence they have in the truth of their derived information, which is in turn a function of the reliability of their sources and their inference methods. An internal procedure, even a very sophisticated one that allows an agent to filter out information that according to its criteria does not exceed a certain threshold of reliability will not be of any use, if it propagates the remaining inferred information as completely reliable information or knowledge. The Semantic Web has the potential to make an immense impact on human society in general and on science in particular.The decisions made in the beginning will be difficult to revise at a later stage. We see, for example, how hard it is to change from a 32 bit IP =ri as address to a 128 bit address. For these reasons we need to be careful what we desi, the foundational formalisms of this Semantic Web. We need to make sure that u.e promote
- 26. Random documents with unrelated content Scribd suggests to you:
- 27. rejected as too poor for use. Such milk has probably been skimmed, or comes from unhealthy or poorly fed cows. The specific gravity of milk should be from 1.027 to 1.033. This may be found with a Quevenne's lactometer. If it falls below 1.027, one has a right to claim that the milk has been watered or that the cows are in poor condition.[16] The reaction of good milk varies from slightly alkaline to slightly acid or neutral. That from the same cow will be different on different days, even under the same apparent conditions of care, varying from one to the other, probably because of some difference in the nature of the food she has eaten. However, if the reaction is decidedly alkaline, and red litmus-paper becomes a distinct blue, the milk is not good, and possibly the animal is diseased. Should the reaction be decidedly acid, it shows that the milk has been contaminated, either from the air by long exposure, or from the vessels which held it, with those micro-organisms which by their growth produce an acid, a certain amount of which causes what is known as "souring." Milk from perfectly healthy and perfectly kept cows is neutral, leaving both red and blue litmus-paper unchanged; but as a general thing milk is slightly acid, even when transported directly from the producer to the consumer and handled by fairly clean workmen in fairly clean vessels. Such milk two or three hours old when examined microscopically is found to contain millions of organisms. Milk is one of the best of foods for bacteria, many of the ordinary forms growing in it with exceeding rapidity under favorable conditions of temperature. Now it has been found that such milk, although it may not contain the seeds of any certain disease, sometimes causes in young children, and the sick, very serious digestive disturbances, and may thus become indirectly the cause of fatal maladies.[17] All milk, unless it is positively known to be given by healthy, well- nourished animals, and kept in thoroughly cleaned vessels free from contamination, should be sterilized before using. Often the organisms found in milk are of disease-giving nature. In Europe and
- 28. America many cases of typhoid fever, scarlatina, and diphtheria have been traced to the milk-supply. In fact milk and water are two of the most fruitful food sources of disease. It therefore immediately becomes apparent that, unless these two liquids are above suspicion, they should be sterilized before using. Boiling water for half an hour will render it sterile, but milk would be injured by evaporation and other changes produced in its constituents by such long exposure to so high a degree of heat. A better method, and one which should be adopted by all who understand something of the nature of bacteria, is to expose the milk for a longer time to a lower temperature than that of boiling. To Sterilize Milk for Immediate Use. (1) Pour the milk into a granite-ware saucepan or a double boiler, raise the temperature to 190° Fahr., and keep it at that point for one hour. (2) As soon as done put it immediately into a pitcher, or other vessel, which has been thoroughly washed, and boiled in a bath of water, and cool quickly by placing in a pan of cold or iced water. A chemist's thermometer, for testing the temperature, may be bought at any pharmacy for a small sum, but if there is not one at hand, heat the milk until a scum forms over the top, and then keep it as nearly as possible at that temperature for one hour. Do not let it boil. To Sterilize Milk which is not for Immediate Use. Put the milk into flasks or bottles with narrow mouths; plug them with a long stopper of cotton-wool, place the flasks in a wire frame to support them, in a kettle of cold water, heat gradually to 190° Fahr., and keep it at that temperature for one hour. Repeat this the second day, for although all organisms were probably destroyed during the first process, spores which may have escaped will have developed into bacteria. These will be killed by the second heating. Repeat again on the third day to destroy any life that may have escaped the first two. Spores or resting-cells are the germinal cells from which new bacteria develop, and are capable of surviving a much higher temperature than the bacteria themselves, as well as desiccation and severe cold.[18] Some writers give a lower temperature than 190°
- 29. Fahr. as safe for sterilization with one hour's exposure, but 190 may be relied upon. Milk treated by the last or "fractional" method of sterilization, as it is called, should keep indefinitely, provided of course the cotton is not disturbed. Cotton-wool or cotton batting in thick masses acts as a strainer for bacteria, and although air will enter, organisms will not. All persons who buy milk, or in any way control milk-supplies, should consider themselves in duty bound to (1) ascertain by personal investigation the condition in which the cows are kept. If there is any suspicion that they are diseased, a veterinary surgeon should be consulted to decide the case. If they are healthy and well fed, they cannot fail to give good milk, and nothing more is to be done except to see that it is transported in perfectly cleansed and scalded vessels. (2) If it is impossible to obtain milk directly from the producer, and one is obliged to buy that from unknown sources, it should be sterilized the moment it enters the house. There is no other means of being sure that it will not be a bearer of disease. Not all such milk contains disease-producing organisms, but it all may contain them, and there is no safety in its use until all bacteria have been deprived of life. DIGESTION Definition. Digestion is the breaking up, changing, and liquefying of the food in the various chambers of the alimentary canal designed for that purpose. The mechanical breaking up is done principally by the teeth in the mouth, the chemical changes and liquefying by the various digestive fluids.[19] Digestive Fluids. The digestive fluids are true secretions. Each is formed from the blood by a special gland for the purpose which never does anything else; they do not exist in the blood as such. Their flow is intermittent, taking place only when they are needed. The liver, however, is an exception to all the others. It is both
- 30. secretory and excretory, and bile is formed all the time, but is most abundant during digestion.[20] Saliva. The fluid which is mixed with the food in the mouth is secreted by a considerable number and variety of glands, the principal of which are the parotid, submaxillary, and sublingual. Smaller glands in the roof and sides of the mouth, in the tongue, and in the mucous membrane of the pharynx contribute to the production of saliva, the digestive fluid of the mouth. The flow from the parotid gland is greatest. The flow from all the glands is greatly increased when food is taken, especially if it be of good flavor. Sometimes the amount is increased by smell alone, as when a nice steak is cooking, or a savory soup, and sometimes the saliva is made copious by thought, as when we remember the taste of dishes eaten in the past, and we say, "It makes the mouth water just to think of them." Amount of Saliva. According to Dalton the amount of saliva secreted every twenty-four hours is 42½ oz. Its reaction is almost constantly alkaline. It is composed of water, organic matter, and various mineral salts. Ptyalin is its active principle, and is called by some authors animal diastase, or starch converter. Gastric Juice. Gastric juice is the digestive fluid of the stomach. It is acid. Its flow is intermittent, occurring only at times of digestion. Its active principle is pepsin. It is worthy of notice here that the character of the digestive fluids when food is taken is different from what it is when the organs are at rest. For instance, the gastric juice which flows in abundance under the stimulus of food, is not like the fluid secreted when the stomach is collapsed and empty. Pancreatic Juice. Pancreatic juice is the digestive juice of the pancreas, and is poured into the small intestine a short distance below the pyloric opening. Its reaction is alkaline. Its flow is entirely suspended during the intervals of digestion.
- 31. Bile. Bile, the fourth in order of the digestive liquids, is the secretion of the largest gland of the body—the liver. It is poured into the small intestine by a duct which empties side by side with the duct from the pancreas. The flow of bile is constant, but is greatest during digestion. Intestinal Juice. Intestinal juice has been to physiologists a difficult subject of study. It is mingled with the salivary and gastric juices at the times of digestion, when it is most desirable to notice its action. Nearly all authorities agree that it is alkaline, and that its function is to complete the digestion of substances which may reach it in an undigested condition. Mucus of Large Intestine. The mucus secreted by the large intestine is for lubricating only. Digestion in Different Parts of the Alimentary Tract. Different substances in food are digested in different portions of the alimentary canal, and by different means. Let us begin in the mouth. Taking the classes of foods, starch, one of the carbohydrates, is the one most affected by the ptyalin, or animal diastase, of the saliva. So energetic is the action of ptyalin on starch that 1 part is sufficient to change 1000 parts. Starch is not acted upon by the gastric juice of the stomach at all; however, the continued action of the saliva is not probably interrupted in the stomach. The digestion of starch is completed by the action of the pancreatic and intestinal juices, and consists in its being changed into soluble glucose, which is absorbed in solution. Sugar. Cane-sugar, or common sugar (also called sucrose), passes through the mouth, unchanged, to the stomach, where it is converted into glucose by the slow action of the acid (hydrochloric) of the gastric juice. Dilute hydrochloric acid has the same action on sugar outside of the stomach. The action of pancreatic juice on sugar is very marked; it immediately changes cane-sugar into glucose. The effect of intestinal fluid is not well understood, but there is the general
- 32. agreement that it does not change cane-sugar, neither is cane-sugar, as such, absorbed in the intestine. Bile does not affect it, therefore cane-sugar is digested or converted into glucose either by the stomach or pancreas, or both. It will now be seen that ultimately the same substance, glucose, is obtained from both starch and sugar. Protein. We now come to the consideration of the digestion of the protein compounds, of which albumen may be taken as a type. Possibly no action except breaking up and moistening takes place in the mouth.[21] Its digestion begins in the stomach, where its structure is broken up and a separation and dissolution of the little sacs which hold it take place. The same thing is partially accomplished outside of the stomach when white of egg is slightly beaten and strained through a cloth. Gastric juice further acts on the albumen itself, forming it into what is called albumen peptone. The digestion of raw and carefully cooked albumen has been found to be carried on very rapidly in the stomach, and the change is essentially the same in both cases, but in favor of the slightly coagulated. When the albumen is rendered hard, fine, and close in consistency by over- cooking, then it is less easy of digestion than when raw. Absorption. It is probable that the greater portion of the process of digestion and absorption of albumen takes place in the stomach. Fibrin. Fibrin is also digested in the stomach, and made into fibrin peptone. Casein. Liquid casein is immediately coagulated by gastric juice, both by the action of free acid and organic matter. Gelatin. Gelatin is quickly dissolved by gastric juice, and afterward no longer has the property of forming jelly on cooling. Gelatin is more rapidly disposed of than the tissue from which it is produced. Vegetable Protein. The digestion of the vegetable protein compounds, such as the gluten of wheat and the protein of the various grains, such as corn, oatmeal, etc., is undoubtedly carried on in the stomach, but they must be well softened and prepared by the
- 33. action of heat and water, or they will not be digested anywhere; and often corn, beans, and grains of oatmeal are rejected entirely unchanged. Partially or imperfectly digested proteins are affected by intestinal juice. It is probable that the function of this fluid is to complete digestive changes in food which have already begun in the stomach. To summarize: The digestion and absorption of nitrogenous compounds take place in both the stomach and the intestines. NUTRITION One of the important points to bring to the notice of pupils in the study of cookery is the phenomenon of nutrition. It is astonishing how vague are the ideas that many people have of why they eat food, and vaguer still are their notions of the necessity of air, pure and plenty. Once instruct the mind that it is the air we breathe and the food we eat which nourish the body, giving material for its various processes, for nervous and muscular energy, and for maintaining the constant temperature which the body must always possess in order to be in a state of health, and there is much more likelihood that the dignity and importance of proper cooking and proper food will not be overlooked. A knowledge that the health and strength of a person depend largely upon what passes through his mouth, that even the turn of his thinking is modified by what he eats, should lead all intelligent women to make food a conscientious subject of study. In general, by the term "nutrition" is meant the building up and maintaining of the physical framework of the body with all its various functions, and ultimately the mental and moral faculties which are dependent upon it, by means of nutriment or food. The word is derived from the Latin nutrire, to nourish. The word "nurse" is from the same root, and in its original sense means one who nourishes, a person who supplies food, tends, or brings up.
- 34. Anything which aids in sustaining the body is food; therefore, air and water, the two most immediate necessities of life, may be, and often are, so classed. Nutriment exclusive of air is received into the body by means of the alimentary canal. The great receiver of air is the lungs, but it also penetrates the body through the pores of the skin, and at these points carbonic acid is given off as in the lungs. The body is often compared to a steam-engine, which takes in raw material in the form of fuel and converts it into force or power. Food, drink, and air are the fuel of the body,—the things consumed; heat, muscular and intellectual energy, and other forms of power are the products. Food, during the various digestive processes, becomes reduced to a liquid, and is then absorbed and conveyed, by different channels constructed for the purpose, into the blood, which contains, after being acted upon by the oxygen of the air in the lungs, all those substances which are required to maintain the various tissues, secretions, and, in fact, the life of the system. Some of the ways in which the different kinds of food nourish the body have been found out by chemists and physiologists from actual experiments on living animals, such as rabbits, dogs, pigs, sheep, goats, and horses, and also on man. Often a scientist becomes so enthusiastic in his search for knowledge about a certain food that he gives his own body for trial. Much valuable work has been done in this direction during the last decade by Voit, Pettenkofer, Moleschott, Ranke, Payen, and in this country by Atwater. No one can explain all the different intricate changes which a particle of food undergoes from the moment it enters the mouth until its final transformation into tissue or some form of energy; but by comparing the income with the outgo, ideas may be gained of what goes on in the economy of the body, and of the proportion of nutrients used, and some of the intricate and complex chemical changes which the different food principles undergo in the various processes of digestion, assimilation, and use.[22] Probably hundreds of changes take place in the body, in its various nutritive functions,
- 35. of which nothing is known, or they are entirely unsuspected, so that if we do our utmost with the present lights which we possess for guidance to health, we shall still fall far short of completeness. The subject of food and nutrition, viewed in the light of bacteriology and chemistry, is one of the most inviting subjects of study of the day, and is worthy of the wisest thought of the nation. The body creates nothing of itself, either of material or of energy; all must come to it from without. Every atom of carbon, hydrogen, phosphorus, or other elements, every molecule of protein, carbohydrate, or other compounds of these elements, is brought to the body with the food and drink it consumes, and the air it breathes. Like the steam-engine, it uses the material supplied to it. Its chemical compounds and energy are the compounds and energy of the food transformed (Atwater). A proof of this is seen in the fact that when the supply from without is cut off, the body dies. The raw material which the body uses is the air and food which it consumes, the greater portion of which is digested and distributed, through the medium of the blood, to all parts of the body, to renew and nourish the various tissues and to supply the material for the different activities of life. Ways in which Food Supplies the Wants of the Body. Food supplies the wants of the body in several ways—(1) it is used to form the tissues of the body—bones, flesh, tendons, skin, and nerves; (2) it is used to repair the waste of the tissues; (3) it is stored in the body for future use; (4) it is consumed as fuel to maintain the constant temperature which the body must always possess to be in a state of health; (5) it produces muscular and nervous energy.[23] The amount of energy of the body depends upon two things—the amount in the food eaten, and the ability of the body to use it, or free it for use. With every motion, and every thought and feeling, material is consumed, hence the more rapid wearing out of persons who do severe work, and of the nervous—those who are keenly susceptible
- 36. to every change in their surroundings, to change of weather, even to the thoughts and feelings of those about them. We easily realize that muscular force or energy cannot be maintained without nutriment in proper quality and amount. An underfed or starving man has not the strength of a well-fed person. He cannot lift the same weight, cannot walk as far, cannot work as hard. We do not as easily comprehend the nervous organism, and generally have less sympathy with worn-out or ill-nourished nerves than muscles, but the sensibilities and the intellectual faculties, of which the nerves and brain are but the instruments, depend upon the right nutrition of the whole system for their proper and healthful exercise. So many factors enter into the make-up of a thought that it cannot be said that any particular kind of food will ultimately produce a poem; but of this we may be sure, that the best work, the noblest thoughts, the most original ideas, will not come from a dyspeptic, underfed, or in any way ill-nourished individual. The classification of foods has been usually based upon the deductions of Prout that milk contains all the necessary nutrients in the best form and proportions, viz., the nitrogenous matters, fat, sugar, water, and salts; the latter being combinations of magnesium, calcium, potassium, sodium, and iron, with chlorin, phosphoric acid, and, in smaller quantities, sulphuric acid. These different classes seem to serve different purposes in the body, and are all necessary for perfect nutrition. Some of them closely resemble each other in composition, but are quite different in their physiological properties, and in the ends which they serve. For instance, starch (C6H10O5) has almost the same chemical formula as sugar (C12H22O11), and yet the one cannot replace the other to its entire exclusion. The Protein Compounds. In general it may be said that the carbohydrates are changed into fats, and are used for the production of force, and that the fats are stored in the body as fat and used as
- 37. fuel. The protein compounds do all that can be done by the fats and carbohydrates, and in addition something more; that is, they form the basis of blood, muscle, sinew, skin, and bone. They are, therefore, the most important of all the food compounds. The terms "power-givers" and "energy-formers" are sometimes applied to them, because wherever power and energy are developed they are present, though not by any means the only substances involved in the evolution of energy. Probably the fats and carbohydrates give most of the material for heat and the various other forces of the body. In case of emergency, where these are deficient, the proteins are used; but protein alone forms the basis of muscle, tendons, skin, and other tissues. This the fats and carbohydrates cannot do (Atwater). The different tissues are known from analysis to contain this complex nitrogenous compound, protein. Now, since the body cannot construct this substance out of the simpler chemical compounds which come to it, it becomes perfectly evident that the diet must have a due proportion of protein in order to maintain the strength of the body. We get most of our proteins from the flesh of animals, and they in turn get it from plants, which construct it from the crude materials of earth and air. The Extractives, usually classed with the protein compounds, such as meat extract, beef tea, etc., are not generally regarded as direct nutrients, but, like tea and coffee, are valuable as accessory foods, lending savor to other foods and aiding their digestion by pleasantly exciting the flow of the digestive fluids. They also act as brain and nerve stimulants, and perhaps also in some slight degree as nutrients. The principal proteins or nitrogenous substances are albumen in various forms, casein both animal and vegetable, blood fibrin, muscle fibrin, and gelatin. All except the last are very much alike, and probably can replace one another in nutrition. Modern chemists agree that nitrogen is a necessary element in the various chemical and physiological actions which take place in the body to produce heat, muscular energy, and the other powers. Every
- 38. structure in the body in which any form of energy is manifested is nitrogenous. The nerves, muscles, glands, and the floating cells[24] in the various liquids are nitrogenous. That nitrogen is necessary to the different processes of the system, is shown by the fact that if it be cut off, these processes languish. This may not occur immediately, for the body always has a store of nitrogen laid by for emergencies which will be consumed first, but it will occur as soon as these have been consumed. The energy of the body is measured by its consumption of oxygen. Motion and heat may be owing to the oxidation of fat, or of starch, or of nitrogenous substances; but whatever the source, the direction is given by the nitrogenous structure—in other words, nitrogen is necessary to all energy generated in the body. Protein matter nourishes the organic framework, takes part in the generation of energy, and may be converted into non-nitrogenous substances.[25] The necessity of the protein compounds is emphasized when we realize that about one half of the body is composed of muscle, one fifth of which is protein, and the nitrogen in this protein can be furnished only by protein, since neither fats nor carbohydrates contain it. It is therefore evident that the protein- containing foods, such as beef, mutton, fish, eggs, milk, and others, are our most valued nutrients. Our daily diet must contain a due proportion. The proteins are all complex chemical compounds, which in nutrition become reduced to simple forms, and are then built up again into flesh. The animal foods are in the main the best of the protein compounds, for they are rich in nitrogenous matter, are easily digested, and from their composition and adaptability are most valuable in maintaining the life of the body. A diet of lean meat alone serves to build up tissue. If nothing else be taken, the stored-up fat of the body will be consumed, and the person will become thin.[26] Athletes while in training take advantage of this fact, and are allowed to eat only such food as shall furnish the greatest amount of strength and muscular energy with a
- 39. minimum of fat. The lean of beef and mutton, with a certain amount of bread, constitute the foundation of the diet. Fats. Most of the fatty substances of food are liquefied at the temperature of the body. When eaten in the form of adipose tissue, as the fat of beef and mutton, the vesicles or cells in which the fat is held are dissociated or dissolved, the fat is set free, and mingles with the digesting mass. This is done in the stomach, and is a preparation for its further change in the intestines. Fats are not dissolved—that is, in the sense in which meats and other foods are dissolved—in the process of digestion; the only change which they undergo is a minute subdivision caused principally by the action of the pancreatic juice. In this condition of fine emulsion they are taken up by the lacteals; they may also be absorbed by the blood-vessels. It has been found that fat emulsions pass more easily through membranes which have been moistened with bile, and it is probable that the function of bile is partly to facilitate the absorption of fat. That the pancreatic juice is the chief agent in forming fats into emulsion was discovered in 1848. Bile is, however, essential to their perfect digestion, and we may therefore say that they are digested by the united action of the pancreatic juice and the bile.[27] Fat forms in the body fatty tissues, and serves for muscular force and heat; it is also necessary to nourish nerves and other tissues,— in fact, without it healthy tissues cannot be formed. A proper amount of fat is also a sort of albumen sparer. It is probable that the fat which is used in the body either to be stored away or for energy, is derived from other sources than directly from the fat eaten. From experiments made by Lawes and Gilbert on pigs, it is evident that the excess of fat stored in their bodies must be derived from some other source than the fat contained in their food, and must be produced partly from nitrogenous matter and partly from carbohydrates, or, at least, that the latter play a part in its formation. It would appear from this that
- 40. life might be maintained on starch, water, salts, and meat free from fat; but although the theory seems a good one, practically it is found in actual experiment[28] that nutrition is impaired by a lack of fat in the diet. The ill effects were soon seen, and immediate relief was given when fat was added to the food. Besides, in the food of all nations starch is constantly associated with some form of fat; bread with butter; potatoes with butter, cream, or gravy; macaroni and polenta with oil, and so forth. A man may live for a time and be healthy with a diet of albuminoids, fats, salts, and water, but it has not yet been proved that a similar result will be produced by a diet of albuminoids, carbohydrates, salts, and water without fat. Fat is necessary to perfect nutrition. Health cannot be maintained on albuminoids, salts, and water alone; but, on the other hand, cannot be maintained without them. Probably the value of fats, as such, is dependent upon the ease with which they are digested. The fats eaten are not stored in the body directly, but the body constructs its fats from those eaten, and from other substances in food,—according to some authorities from the carbohydrates and proteids, and according to others from proteids alone. Fats are stored away as fat, furnish heat, and are used for energy; at least, it is probable that at times they are put to the latter use. The fats laid by in the body for future use last in cases of starvation quite a long time, depending, of course, upon the amount. At such times a fat animal will live longer than a lean one. Doubtless in the fat of food the body finds material for its fats in the most easily convertible form. Of the various fatty substances taken, some are more easily assimilated than others. Dr. Fothergill, in "The Town Dweller," says that the reason that cod-liver oil is given to delicate children and invalids is, that it is more easily digested than ordinary fats, but it is an inferior form of fat; the next most easily digested is the fat of bacon. When a child can take bread crumbled in a little of this fat, it will not be necessary to give him cod-liver oil. Bacon fat is the much better fat for building tissues.
- 41. Then comes cream, a natural emulsion, and butter. He further says there is one form of fat not commonly looked at in its proper dietetic value, and that is "toffee." It is made of butter, sugar, and sometimes a portion of molasses. A quantity of this, added to the ordinary meals, will enable a child in winter to keep up the bodily heat. The way in which butter in the form of toffee goes into the stomach is particularly agreeable. Carbohydrates. The principal carbohydrates are starch, dextrine, cane-sugar or common table sugar, grape-sugar, the principal sugar in fruits, and milk-sugar, the natural sugar in milk. They are substances made up, as before stated, of carbon, hydrogen, and oxygen, but no nitrogen. They are important food substances, but are of themselves incapable of sustaining life. The carbohydrates, both starch and sugar, in the process of digestion are converted into glucose. This is stored in the liver in the form of glycogen, which the liver has the power of manufacturing; it then passes into the circulation, and is distributed to the different parts of the body as it is needed. (The liver also has the power of forming glycogen out of other substances than sugar, and it is pretty conclusively proved that it is from proteids, and not from fats. Carnivorous animals, living upon flesh alone, are found to have glycogen in their bodies.) It is impossible to assign any especial office to the different food principles; that is, it cannot be said that the carbohydrates perform a certain kind of work in the body and nothing else, or that the proteids or fats do. The human body is a highly complex and intricate organism, and its maintenance is carried on by complex and mysterious processes that cannot be followed, except imperfectly; consequently, we must regard the uses of foods in the body as more or less involved in obscurity. It is, however, generally understood that the proteids, fats, and carbohydrates each do an individual work of their own better than either of the others can do it. They are all necessary in due amount to the nutrition of the body, and doubtless work together as well as in their separate functions. They are,
- 42. however, sometimes interchangeable, as, for instance, in the absence of the carbohydrates, proteids will do their work. The carbohydrates are eminently heat and energy formers, and they also act as albumen sparers. The body always has a store of material laid by for future use. If it were not for this a person deprived of food would die immediately, as is the case when he is deprived of oxygen. (Air being ever about us, and obtainable without effort or price, there is no need for the body to lay by an amount of oxygen; consequently only a very little is stored, and that in the blood.) The great reserve forces of the body are in the form of fatty tissues, and glycogen, or the stored-away carbohydrates of the liver; the latter is given out to the body as it is needed during the intervals of eating to supply material for the heat and energy of daily consumption, and in case of starvation. That they are true reserves is shown by the fact that they disappear during deprivation of food. The glycogen, or liver-supply, disappears first; then the fat (Martin). The heat of the body can be maintained on these substances, and a certain amount of work done, although no food except water be taken. The principal function of the liver is to form glycogen to be stored away. It constantly manufactures it, and as constantly loses it to the circulation. Glycogen is chemically allied to starch, having the same formula (C6H10O5), but differing in other ways. Its quantity is greatest about two hours after a full meal; then it gradually falls, but increases again when food is again taken. Its amount also varies with the kind of food eaten: fats and proteids by themselves give little, but starch and sugars give much, for it is found in greatest quantity when these form a part of the diet. Inorganic Matter and Vegetable Acids. Water and other inorganic matter, as the salts of different kinds, and vegetable acids, as vinegar and lemon-juice, can scarcely be said to be digested. Water is absorbed, and salts are generally in solution in liquids and are absorbed with them.
- 43. Water is found in all parts of the body, even in the very solid portions, as the bones and the enamel of the teeth; it also constitutes a large proportion of its semisolids and fluids, some of which are nearly all water, as the perspiration and the tears. Water usually is found combined with some of the salts, which seem to act as regulators of the amount which shall be incorporated into a tissue. Water is a necessary constituent of all tissues, giving them a proper consistency and elasticity. The power of resistance of the bones could not be maintained without it. It is also valuable as a food solvent, assisting in the liquefying of different substances, which are taken up by the various absorbent tubes, conveyed into the blood, and so circulated through the body. Most of the water of the body is taken into it from without, but it is also formed in the body by the union of hydrogen and oxygen.[29] Sodium chlorid, or common salt, is found in the blood and other fluids, and in the solids of the body, except the enamel of the teeth; it occurs in greatest proportion in the fluids. The part that this salt plays in nutrition is not altogether understood. "Common salt is intermediate in certain general processes, and does not participate by its elements in the formation of organs" (Liebig). Salt is intimately associated with water, which plays an intermediate part also in nutrition, being a bearer or carrier of nutritious matters through the body. Salt seems to regulate the absorption and use of nutrients. It is found in the greatest quantity in the blood and chyle. It doubtless facilitates digestion by rendering foods more savory, and thus causing the digestive juices to flow more freely. Sodium chlorid is contained in most if not all kinds of food, but not in sufficient quantity to supply the wants of the body; it therefore becomes a necessary part of a diet. Potassium chlorid has similar uses to sodium chlorid, although not so generally distributed through the body. It is found in muscle, liver, milk, chyle, blood, mucus, saliva, bile, gastric juice, and one or two other fluids.
- 44. Calcium phosphate is found in all the fluids and solids of the body, held in solution in them by the presence of CO2; both it and calcium carbonate enter largely into the structure of the bones. Sodium carbonate, magnesium phosphate, and other salts play important parts in nutrition. The various salts influence chemical change as well as act in rendering food soluble. For example, serum albumen, the chief proteid of the blood, is insoluble in pure water, but dissolves easily in water which has a little neutral salts in it.[30] Salts also help to give firmness to the teeth and bones. To recapitulate, food is eaten, digested, assimilated, and consumed or transformed in the body by a series of highly intricate and complex processes. It is for the most part used for the different powers and activities of the system; there is, however, always a small portion which is rejected as waste. The first change is in the mouth, where the food is broken up and moistened and the digestion of starch begins; these changes continue in the stomach until the whole is reduced to a more or less liquid mass. As the contents of the stomach pass little by little into the duodenum, the mass becomes more fluid by the admixture of bile, pancreatic juice, and intestinal juice, and, as it passes along, absorption takes place; the mass grows darker in color and less fluid, until all good material is taken up and only waste left, which is rejected from the body. That portion of the food which is not affected by the single or united action of the digestive fluids is chiefly of vegetable origin. Hard seeds, such as corn, and the outer coverings of grains, such as the husk of oatmeal and those parts which are composed largely of cellulose, pass through the intestinal canal without change. It may be remarked here that since the digestive mechanism is so perfect a structure, and will try to dissolve anything given it, and select only that which is good, why should there be the necessity of giving any special attention to preparing food before it is eaten? The answer is that the absorptive vessels cannot take up what is not
- 45. there, neither can the digestive organs supply what the food lacks; therefore, the food must contain in suitable proportions all substances needed by the body. Also, food which contains a large proportion of waste, or is difficult of digestion from over or under cooking, or is unattractive by insipidity or unsavoriness, overworks these long-suffering organs (the extra power or force needed being drawn from the blood), and causes the whole system to suffer. Mal- nutrition, with the long line of evils which it entails, is the cause, direct or indirect, of most of the sickness in the world, for it reduces the powers of the system, and thus enfeebles its resistance to disease. Ideal Diet. "The ideal diet is that combination of food which, while imposing the least burden upon the body, supplies it with exactly sufficient material to meet its wants" (Schuster). In general the digestibility of foods may be summarized as follows:
- 46. 1. The protein of ordinary animal foods is very readily and completely digestible. 2. The protein of vegetable foods is much less easily digested than that of animal foods. 3. The fat of animal foods may at times fail of digestion. 4. Sugar and starch are easy of digestion. 5. Animal foods have the advantage of vegetable foods in that they contain more protein, and that their protein is more easily digested. (Atwater.) A diet largely of animal food leaves very little undigested matter. The albuminoids in all cases are completely transformed into nutriment. Fat enters the blood as a fine emulsion. Absorption. The general rule of absorption is that food is taken into the circulation through the porous walls of the alimentary tract as rapidly as it is completely digested. A large portion of liquid is immediately absorbed by the blood-vessels of the stomach. Adaptation of Foods to Particular Needs and Conditions. The demands of different individuals for nutrients in the daily food vary with age, occupation, and other conditions of life, including especially the peculiar characteristics of people. No two persons are exactly alike in their expenditure of muscular and nervous energy, so no two will need the same amount or kind of nutriment to repair the waste. A man who digs in a field day after day expends a certain amount of muscular energy. A lawyer, statesman, or author who works with his brain instead of his hands uses nervous force, but very little muscular. Brain and muscle are not nourished exactly by the same materials; therefore, the demand in the way of nutriment of these two classes will not be the same. The lawyer might find a feast in a box of sardines and some biscuit, while the field laborer would look with contempt upon such food, and turn from it to fat pork and cabbage. This is no mere difference in refinement of taste, but a real and instinctive difference in the demands of the two constitutions. Sardines supply to the
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