Information retrieval 7 boolean model
- 1. Information Retrieval : 7 Boolean Model Prof Neeraj Bhargava Vaibhav Khanna Department of Computer Science School of Engineering and Systems Sciences Maharshi Dayanand Saraswati University Ajmer
- 2. The Boolean Model âą Simple model based on set theory and Boolean algebra âą Queries specified as boolean expressions â quite intuitive and precise semantics â neat formalism â example of query âą Term-document frequencies in the term-document matrix are all binary
- 3. âą The (standard) Boolean model of information retrieval (BIR) is a classical information retrieval (IR) model and, at the same time, the first and most-adopted one. ... âą The BIR is based on Boolean logic and classical set theory in that both the documents to be searched and the user's query are conceived as sets of terms âą Retrieval is based on whether the documents contain the query terms or not .
- 4. The Boolean Model âą A term conjunctive component that satisfies a query q is called a query conjunctive component c(q) âą A query q rewritten as a disjunction of those components is called the disjunct normal form qDNF âą To illustrate, consider
- 5. The Boolean Model âą The three conjunctive components for the query
- 6. The Boolean Model âą This approach works even if the vocabulary of the collection includes terms not in the query âą Consider that the vocabulary is given by âą Then, a document dj that contains only terms ka, kb, and kc is represented by c(dj) = (1, 1, 1, 0)
- 7. The Boolean Model âą The similarity of the document dj to the query q is defined as âą The Boolean model predicts that each document is either relevant or non-relevant
- 8. Advantages of Boolean Model âą Clean formalism âą Easy to implement âą Intuitive concept
- 9. Disadvantages of Boolean Model âą Exact matching may retrieve too few or too many documents âą Hard to translate a query into a Boolean expression âą All terms are equally weighted âą More like data retrieval than information retrieval
- 10. Drawbacks of the Boolean Model âą Retrieval based on binary decision criteria with no notion of partial matching âą No ranking of the documents is provided (absence of a grading scale) âą Information need has to be translated into a Boolean expression, which most users find awkward âą The Boolean queries formulated by the users are most often too simplistic âą The model frequently returns either too few or too many documents in response to a user query
- 11. Assignment âą Explain the Boolean Model of Information Retrieval.