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Semantics-aware Graph-based
Recommender Systems exploiting
Linked Open Data
Cataldo Musto, Pasquale Lops, Pierpaolo Basile,
Marco de Gemmis Giovanni Semeraro
(Università degli Studi di Bari ‘Aldo Moro’, Italy - SWAP Research Group)
UMAP 2016
24th Conference on User Modeling,
Adaptation and Personalization
Halifax (Canada)
July 15, 2016
2
Linked Open Data
Cataldo Musto, Pasquale Lops, Pierpaolo Basile, Marco de Gemmis, Giovanni Semeraro
Semantics-aware Graph-based Recommender Systems Exploiting Linked Open Data. UMAP 2016, Halifax (Canada). 15.07.2016
3
Linked Open Data
Methodology to publish, share and link
structured data on the Web
Definition
Cataldo Musto, Pasquale Lops, Pierpaolo Basile, Marco de Gemmis, Giovanni Semeraro
Semantics-aware Graph-based Recommender Systems Exploiting Linked Open Data. UMAP 2016, Halifax (Canada). 15.07.2016
4
Linked Open Data
Cornerstones
1.
2.
Use of RDF to publish data on the Web
Re-Use of existing properties to express
an agreed semantics and connect data sources
Cataldo Musto, Pasquale Lops, Pierpaolo Basile, Marco de Gemmis, Giovanni Semeraro
Semantics-aware Graph-based Recommender Systems Exploiting Linked Open Data. UMAP 2016, Halifax (Canada). 15.07.2016
5
Linked Open Data (cloud)
What is it?
A (large) set of interconnected semantic datasets
Cataldo Musto, Pasquale Lops, Pierpaolo Basile, Marco de Gemmis, Giovanni Semeraro
Semantics-aware Graph-based Recommender Systems Exploiting Linked Open Data. UMAP 2016, Halifax (Canada). 15.07.2016
6
Linked Open Data (cloud)
What kind of datasets?
Each bubble is a dataset!
Cataldo Musto, Pasquale Lops, Pierpaolo Basile, Marco de Gemmis, Giovanni Semeraro
Semantics-aware Graph-based Recommender Systems Exploiting Linked Open Data. UMAP 2016, Halifax (Canada). 15.07.2016
7
Linked Open Data (cloud)
How many data?
9960 datasets and 149 billions triplessource: http://stats.lod2.eu
today!
Cataldo Musto, Pasquale Lops, Pierpaolo Basile, Marco de Gemmis, Giovanni Semeraro
Semantics-aware Graph-based Recommender Systems Exploiting Linked Open Data. UMAP 2016, Halifax (Canada). 15.07.2016
8
Linked Open Data (cloud)
DBpedia is the structured RDF mapping of Wikipedia
http://dbpedia.org
It is the core of the LOD cloud.
DBpedia
Cataldo Musto, Pasquale Lops, Pierpaolo Basile, Marco de Gemmis, Giovanni Semeraro
Semantics-aware Graph-based Recommender Systems Exploiting Linked Open Data. UMAP 2016, Halifax (Canada). 15.07.2016
9
Linked Open Data (cloud)
Example: unstructured content from Wikipedia
example (Wikipedia page)
Cataldo Musto, Pasquale Lops, Pierpaolo Basile, Marco de Gemmis, Giovanni Semeraro
Semantics-aware Graph-based Recommender Systems Exploiting Linked Open Data. UMAP 2016, Halifax (Canada). 15.07.2016
10
Linked Open Data (cloud)
How are these data represented?
The Matrix
Don Davis
http://dbpedia.org/resource/Category:Films_shot_in_Australia
Films shot in
Australia
dcterms:subject
dbpedia-owl:m
usicCom
poser
http://dbpedia.org/resource/Don_Davis_(composer)

dcterms:subject
dcterm
s:subject
dbo:runtimedbpedia-owl:director
dcterm
s:subject
dcterm
s:subject
Dystopian Films136
American Action
Thriller Films
Cyberpunk Films The Wachowskis
http://dbpedia.org/resource/The_Wachowskis
http://dbpedia.org/resource/Dystopian_FIlms
http://dbpedia.org/resource/Cyberpunk_Films
http://dbpedia.org/resource/American_Action_Thriller_FIlms
http://dbpedia.org/resource/Films_About_Rebellions
Films about
Rebellions
Several interesting (non-trivial) features come into play!
Cataldo Musto, Pasquale Lops, Pierpaolo Basile, Marco de Gemmis, Giovanni Semeraro
Semantics-aware Graph-based Recommender Systems Exploiting Linked Open Data. UMAP 2016, Halifax (Canada). 15.07.2016
11
Linked Open Data (cloud)
How are these data represented?
The Matrix
Don Davis
http://dbpedia.org/resource/Category:Films_shot_in_Australia
Films shot in
Australia
dcterms:subject
dbpedia-owl:m
usicCom
poser
http://dbpedia.org/resource/Don_Davis_(composer)

dcterms:subject
dcterm
s:subject
dbo:runtimedbpedia-owl:director
dcterm
s:subject
dcterm
s:subject
Dystopian Films136
American Action
Thriller Films
Cyberpunk Films The Wachowskis
http://dbpedia.org/resource/The_Wachowskis
http://dbpedia.org/resource/Dystopian_FIlms
http://dbpedia.org/resource/Cyberpunk_Films
http://dbpedia.org/resource/American_Action_Thriller_FIlms
http://dbpedia.org/resource/Films_About_Rebellions
Films about
Rebellions
Several interesting (non-trivial) features come into play!
Cataldo Musto, Pasquale Lops, Pierpaolo Basile, Marco de Gemmis, Giovanni Semeraro
Semantics-aware Graph-based Recommender Systems Exploiting Linked Open Data. UMAP 2016, Halifax (Canada). 15.07.2016
12
Research Questions
(1) Can we use Linked Open Data for
Recommender Systems?
Cataldo Musto, Pasquale Lops, Pierpaolo Basile, Marco de Gemmis, Giovanni Semeraro
Semantics-aware Graph-based Recommender Systems Exploiting Linked Open Data. UMAP 2016, Halifax (Canada). 15.07.2016
13
Research Questions
(2) Is it possible to automatically select the most promising
properties among those available in the LOD cloud?
Cataldo Musto, Pasquale Lops, Pierpaolo Basile, Marco de Gemmis, Giovanni Semeraro
Semantics-aware Graph-based Recommender Systems Exploiting Linked Open Data. UMAP 2016, Halifax (Canada). 15.07.2016
14
i4
u1
u2
u3
u4
Methodology
Graph-based Data Model - original representation
Original
Graph-based
data model
Users and Items are
connected according
to users’ preferences
Cataldo Musto, Pasquale Lops, Pierpaolo Basile, Marco de Gemmis, Giovanni Semeraro
Semantics-aware Graph-based Recommender Systems Exploiting Linked Open Data. UMAP 2016, Halifax (Canada). 15.07.2016
15
i4
u1
u2
u3
u4
Methodology
Graph-based Data Model - DBpedia Mapping
If we are able to
map the items in
the dataset with
the
entities in the
LOD cloud, our
representation can
be extended with
new data points
Cataldo Musto, Pasquale Lops, Pierpaolo Basile, Marco de Gemmis, Giovanni Semeraro
Semantics-aware Graph-based Recommender Systems Exploiting Linked Open Data. UMAP 2016, Halifax (Canada). 15.07.2016
16
i4
u1
u2
u3
u4
dcterms:subject
http://dbpedia.org/resource/Films_About_Rebellions
Films about
Rebellions
dbprop:director
Quentin Tarantino
dbprop:director
Methodology
Graph-based Data Model - LOD-boosted representation
1999 films
http://dbpedia.org/resource/1999_films
dcterms:subject
dcterms:subject
Cataldo Musto, Pasquale Lops, Pierpaolo Basile, Marco de Gemmis, Giovanni Semeraro
Semantics-aware Graph-based Recommender Systems Exploiting Linked Open Data. UMAP 2016, Halifax (Canada). 15.07.2016
17
i4
u1
u2
u3
u4
dcterms:subject
http://dbpedia.org/resource/Films_About_Rebellions
Films about
Rebellions
dbprop:director
Quentin Tarantino
dbprop:director
Methodology
example - LOD-boosted representation
1999 films
http://dbpedia.org/resource/1999_films
dcterms:subject
dcterms:subject
Many new information
can be injected in the
graph
Cataldo Musto, Pasquale Lops, Pierpaolo Basile, Marco de Gemmis, Giovanni Semeraro
Semantics-aware Graph-based Recommender Systems Exploiting Linked Open Data. UMAP 2016, Halifax (Canada). 15.07.2016
18
i4
u1
u2
u3
u4
dcterms:subject
http://dbpedia.org/resource/Films_About_Rebellions
Films about
Rebellions
dbprop:director
Quentin Tarantino
dbprop:director
Methodology
example - LOD-boosted representation
1999 films
http://dbpedia.org/resource/1999_films
dcterms:subject
dcterms:subject
How to get
recommendations?
Cataldo Musto, Pasquale Lops, Pierpaolo Basile, Marco de Gemmis, Giovanni Semeraro
Semantics-aware Graph-based Recommender Systems Exploiting Linked Open Data. UMAP 2016, Halifax (Canada). 15.07.2016
19
Graph-based Recommendation Algorithm
Insight:
- Calculate PageRank score for each item node.
- Sort PageRank scores in a descending order.
- Select top-k recommendations
PageRank with Priors
. T. H. Haveliwala. Topic-Sensitive PageRank: A
Context-Sensitive Ranking Algorithm for Web
Search. IEEE Trans. Knowl. Data Eng., 15(4):
784–796, 2003. 

Reference
Cataldo Musto, Pasquale Lops, Pierpaolo Basile, Marco de Gemmis, Giovanni Semeraro
Semantics-aware Graph-based Recommender Systems Exploiting Linked Open Data. UMAP 2016, Halifax (Canada). 15.07.2016
20
i4
u1
u2
u3
u4
dcterms:subject
http://dbpedia.org/resource/Films_About_Rebellions
Films about
Rebellions
dbprop:director
Quentin Tarantino
dbprop:director
Methodology
example - LOD-boosted representation
1999 films
http://dbpedia.org/resource/1999_films
dcterms:subject
dcterms:subject
Is it possibile to
automatically select
the most promising
properties?
Cataldo Musto, Pasquale Lops, Pierpaolo Basile, Marco de Gemmis, Giovanni Semeraro
Semantics-aware Graph-based Recommender Systems Exploiting Linked Open Data. UMAP 2016, Halifax (Canada). 15.07.2016
21
i4
u1
u2
u3
u4
dcterms:subject
http://dbpedia.org/resource/Films_About_Rebellions
Films about
Rebellions
dbprop:director
Quentin Tarantino
dbprop:director
Methodology
example - LOD-boosted representation
1999 films
http://dbpedia.org/resource/1999_films
dcterms:subject
dcterms:subject
X
X
Cataldo Musto, Pasquale Lops, Pierpaolo Basile, Marco de Gemmis, Giovanni Semeraro
Semantics-aware Graph-based Recommender Systems Exploiting Linked Open Data. UMAP 2016, Halifax (Canada). 15.07.2016
22
i4
u1
u2
u3
u4
dcterms:subject
http://dbpedia.org/resource/Films_About_Rebellions
Films about
Rebellions
dbprop:director
Quentin Tarantino
dbprop:director
Methodology
example - LOD-boosted representation
1999 films
http://dbpedia.org/resource/1999_films
dcterms:subject
dcterms:subject
X
X
X
Cataldo Musto, Pasquale Lops, Pierpaolo Basile, Marco de Gemmis, Giovanni Semeraro
Semantics-aware Graph-based Recommender Systems Exploiting Linked Open Data. UMAP 2016, Halifax (Canada). 15.07.2016
23
Experiments
Cataldo Musto, Pasquale Lops, Pierpaolo Basile, Marco de Gemmis, Giovanni Semeraro
Semantics-aware Graph-based Recommender Systems Exploiting Linked Open Data. UMAP 2016, Halifax (Canada). 15.07.2016
24
Research Questions
Do graph-based
recommender systems
benefit of the introduction
of LOD-based features?
Do graph-based
recommender systems
exploiting LOD benefit of
the adoption of feature
selection techniques?
1/2
1.
2.
Cataldo Musto, Pasquale Lops, Pierpaolo Basile, Marco de Gemmis, Giovanni Semeraro
Semantics-aware Graph-based Recommender Systems Exploiting Linked Open Data. UMAP 2016, Halifax (Canada). 15.07.2016
25
Research Questions
3.
4.
2/2
Is there any correlation
between the choice of the
FS technique and the
behavior of the algorithm?
(e.g., better diversity or
better F1) ?
How does our
methodology perform
with respect to state-of-
the-art algorithms?
Cataldo Musto, Pasquale Lops, Pierpaolo Basile, Marco de Gemmis, Giovanni Semeraro
Semantics-aware Graph-based Recommender Systems Exploiting Linked Open Data. UMAP 2016, Halifax (Canada). 15.07.2016
26
Experimental Evaluation
Description of the dataset
MovieLens 100k
983 users
1,682 movies
100,000 ratings
55.17% positive ratings
84.43 ratings/user (avg.)
48.48 ratings/item (avg.)
93.7% sparsity
Cataldo Musto, Pasquale Lops, Pierpaolo Basile, Marco de Gemmis, Giovanni Semeraro
Semantics-aware Graph-based Recommender Systems Exploiting Linked Open Data. UMAP 2016, Halifax (Canada). 15.07.2016
27
Experimental Evaluation
Description of the dataset
DBbook dataset
6,181 users
6,733 movies
72,372 ratings
45,85% positive ratings
11.70 ratings/user (avg.)
10.74 ratings/item (avg.)
99.8% sparsity
Cataldo Musto, Pasquale Lops, Pierpaolo Basile, Marco de Gemmis, Giovanni Semeraro
Semantics-aware Graph-based Recommender Systems Exploiting Linked Open Data. UMAP 2016, Halifax (Canada). 15.07.2016
28
Experimental Evaluation
Graph Representations :: Recap
G
Basic Graph with
collaborative data points
Cataldo Musto, Pasquale Lops, Pierpaolo Basile, Marco de Gemmis, Giovanni Semeraro
Semantics-aware Graph-based Recommender Systems Exploiting Linked Open Data. UMAP 2016, Halifax (Canada). 15.07.2016
29
Experimental Evaluation
GLOD Graph extended with all the properties
gathered from the LOD cloud
Graph Representations :: Recap
Cataldo Musto, Pasquale Lops, Pierpaolo Basile, Marco de Gemmis, Giovanni Semeraro
Semantics-aware Graph-based Recommender Systems Exploiting Linked Open Data. UMAP 2016, Halifax (Canada). 15.07.2016
30
Experimental Evaluation
GLOD+FS
Graph encoding only the most relevant properties
selected by a feature selection technique FS
Graph Representations :: Recap
Cataldo Musto, Pasquale Lops, Pierpaolo Basile, Marco de Gemmis, Giovanni Semeraro
Semantics-aware Graph-based Recommender Systems Exploiting Linked Open Data. UMAP 2016, Halifax (Canada). 15.07.2016
31
Experimental Evaluation
Experimental Protocol
Algorithm PageRank with Priors
Data Split
5-fold Cross Validation for MovieLens
Train/Test for DBbook
Graph Representation G, GLOD, GLOD+FS
Feature Selection Techniques
PageRank, Chi-Square, Information
Gain, Gain Ratio, mRMR, PCA, SVM
#Selected Features top-10, top-30, top-50 properties
Evaluation Metrics F1, Intra-List Diversity, Run Time
Cataldo Musto, Pasquale Lops, Pierpaolo Basile, Marco de Gemmis, Giovanni Semeraro
Semantics-aware Graph-based Recommender Systems Exploiting Linked Open Data. UMAP 2016, Halifax (Canada). 15.07.2016
Experiment 1
32
Impact of LOD-based features.
Cataldo Musto, Pasquale Lops, Pierpaolo Basile, Marco de Gemmis, Giovanni Semeraro
Semantics-aware Graph-based Recommender Systems Exploiting Linked Open Data. UMAP 2016, Halifax (Canada). 15.07.2016
F1@5
F1@10
G
G_LOD
G
G_LOD
53 55 57 59 61
60,83
54,24
60,23
53,89
Experiment 1
33
Impact of LOD-based features :: F1-measure
Improvement only on MovieLens
F1@5
F1@10
G
G_LOD
G
G_LOD
53 56 59 62 65
64,21
55,04
64,31
55,02
MovieLens
DBbook
Cataldo Musto, Pasquale Lops, Pierpaolo Basile, Marco de Gemmis, Giovanni Semeraro
Semantics-aware Graph-based Recommender Systems Exploiting Linked Open Data. UMAP 2016, Halifax (Canada). 15.07.2016
Run Time (min.)
G
G_LOD
50 262,5 475 687,5 900
880
72
Experiment 1
34
Tremendous increase in the run time
Impact of LOD-based features :: Run Time
Run Time (min.)
G
G_LOD
50 662,5 1275 1887,5 2500
2.433
100
MovieLens
DBbook
Cataldo Musto, Pasquale Lops, Pierpaolo Basile, Marco de Gemmis, Giovanni Semeraro
Semantics-aware Graph-based Recommender Systems Exploiting Linked Open Data. UMAP 2016, Halifax (Canada). 15.07.2016
Experiment 2
35
Impact of Feature Selection techniques
Cataldo Musto, Pasquale Lops, Pierpaolo Basile, Marco de Gemmis, Giovanni Semeraro
Semantics-aware Graph-based Recommender Systems Exploiting Linked Open Data. UMAP 2016, Halifax (Canada). 15.07.2016
Experiment 2
36
GLOD (baseline) = 54,24
Impact of Feature Selection :: MovieLens :: F1@5
Cataldo Musto, Pasquale Lops, Pierpaolo Basile, Marco de Gemmis, Giovanni Semeraro
Semantics-aware Graph-based Recommender Systems Exploiting Linked Open Data. UMAP 2016, Halifax (Canada). 15.07.2016
PageRank
mRMR
Chi-Square
SVM
Gain Ratio
Inf. Gain
PCA
10
30
50
10
30
50
10
30
50
10
30
50
10
30
50
10
30
50
10
30
50
53 53,5 54 54,5 55
54,31
54,12
54,06
54,21
54,2
54,21
54,12
54,13
53,96
53,98
54,13
54,19
54,29
54,29
54,06
53,97
53,72
53,82
54,14
53,97
54,18
PageRank
mRMR
Chi-Square
SVM
Gain Ratio
Inf. Gain
PCA
10
30
50
10
30
50
10
30
50
10
30
50
10
30
50
10
30
50
10
30
50
53 53,5 54 54,5 55
54,31
54,12
54,06
54,21
54,2
54,21
54,12
54,13
53,96
53,98
54,13
54,19
54,29
54,29
54,06
53,97
53,72
53,82
54,14
53,97
54,18
Experiment 2
37
Tree out of seven techniques
(and only with 50 features) overcome the baseline
Impact of Feature Selection :: MovieLens :: F1@5
Cataldo Musto, Pasquale Lops, Pierpaolo Basile, Marco de Gemmis, Giovanni Semeraro
Semantics-aware Graph-based Recommender Systems Exploiting Linked Open Data. UMAP 2016, Halifax (Canada). 15.07.2016
PageRank
mRMR
Chi-Square
SVM
Gain Ratio
Inf. Gain
PCA
10
30
50
10
30
50
10
30
50
10
30
50
10
30
50
10
30
50
10
30
50
53 53,5 54 54,5 55
54,31
54,12
54,06
54,21
54,2
54,21
54,12
54,13
53,96
53,98
54,13
54,19
54,29
54,29
54,06
53,97
53,72
53,82
54,14
53,97
54,18
Experiment 2
38
Typically, the larger the number of features, the better the F1
#50
#50
#50
#50
#50
#30
#30
(best)
Impact of Feature Selection :: MovieLens :: F1@5
Cataldo Musto, Pasquale Lops, Pierpaolo Basile, Marco de Gemmis, Giovanni Semeraro
Semantics-aware Graph-based Recommender Systems Exploiting Linked Open Data. UMAP 2016, Halifax (Canada). 15.07.2016
PageRank
mRMR
Chi-Square
SVM
Gain Ratio
Inf. Gain
PCA
10
30
50
10
30
50
10
30
50
10
30
50
10
30
50
10
30
50
10
30
50
63,5 63,825 64,15 64,475 64,8
64,286
64,19
64,25
64,26
64,19
64,19
64,18
64,32
64,27
64,31
64,3
64,2
64,27
64,22
64,33
64,45
64,35
64,34
64,23
64,35
64,31
Experiment 2
39
#10
#10
#10
#10
#10
#10
Impact of Feature Selection :: DBbook :: F1@10
#10
GLOD (baseline) = 64,20
Cataldo Musto, Pasquale Lops, Pierpaolo Basile, Marco de Gemmis, Giovanni Semeraro
Semantics-aware Graph-based Recommender Systems Exploiting Linked Open Data. UMAP 2016, Halifax (Canada). 15.07.2016
PageRank
mRMR
Chi-Square
SVM
Gain Ratio
Inf. Gain
PCA
10
30
50
10
30
50
10
30
50
10
30
50
10
30
50
10
30
50
10
30
50
63,5 63,825 64,15 64,475 64,8
64,286
64,19
64,25
64,26
64,19
64,19
64,18
64,32
64,27
64,31
64,3
64,2
64,27
64,22
64,33
64,45
64,35
64,34
64,23
64,35
64,31
Experiment 2
40
#10
#10
#10
#10
#10
#10
Impact of Feature Selection :: DBbook :: F1@10
#10
All the techniques
overcome the baseline at least once
Cataldo Musto, Pasquale Lops, Pierpaolo Basile, Marco de Gemmis, Giovanni Semeraro
Semantics-aware Graph-based Recommender Systems Exploiting Linked Open Data. UMAP 2016, Halifax (Canada). 15.07.2016
PageRank
mRMR
Chi-Square
SVM
Gain Ratio
Inf. Gain
PCA
10
30
50
10
30
50
10
30
50
10
30
50
10
30
50
10
30
50
10
30
50
63,5 63,825 64,15 64,475 64,8
64,286
64,19
64,25
64,26
64,19
64,19
64,18
64,32
64,27
64,31
64,3
64,2
64,27
64,22
64,33
64,45
64,35
64,34
64,23
64,35
64,31
Experiment 2
41
On DBbook best results are obtained with 10 features!
#10
#10
#10
#10
#10
#10
(best)
Impact of Feature Selection :: DBbook :: F1@10
#10
Cataldo Musto, Pasquale Lops, Pierpaolo Basile, Marco de Gemmis, Giovanni Semeraro
Semantics-aware Graph-based Recommender Systems Exploiting Linked Open Data. UMAP 2016, Halifax (Canada). 15.07.2016
Run Time (min.) - MovieLens
GLOD
GLOD+PCA
50 262,5 475 687,5 900
581
880
Experiment 2
42
Significant decrease
Impact of Feature Selection techniques :: Run Time
Run Time (min.) - DBbook
GLOD
GLOD+IG
50 687,5 1325 1962,5 2600
1.341
2433
Cataldo Musto, Pasquale Lops, Pierpaolo Basile, Marco de Gemmis, Giovanni Semeraro
Semantics-aware Graph-based Recommender Systems Exploiting Linked Open Data. UMAP 2016, Halifax (Canada). 15.07.2016
Experiment 3
43
Trade-off between F1 and diversity
Cataldo Musto, Pasquale Lops, Pierpaolo Basile, Marco de Gemmis, Giovanni Semeraro
Semantics-aware Graph-based Recommender Systems Exploiting Linked Open Data. UMAP 2016, Halifax (Canada). 15.07.2016
Experiment 3
44
Trade-off between F1 and diversity
Can the choice of the feature selection technique
endogenously induce an higher diversity (or,
respectively, an higher F1) of the recommendations?
Cataldo Musto, Pasquale Lops, Pierpaolo Basile, Marco de Gemmis, Giovanni Semeraro
Semantics-aware Graph-based Recommender Systems Exploiting Linked Open Data. UMAP 2016, Halifax (Canada). 15.07.2016
Experiment 3
45
Trade-off between F1 and diversity :: MovieLens :: F1@5
G_LOD = Baseline
Cataldo Musto, Pasquale Lops, Pierpaolo Basile, Marco de Gemmis, Giovanni Semeraro
Semantics-aware Graph-based Recommender Systems Exploiting Linked Open Data. UMAP 2016, Halifax (Canada). 15.07.2016
Experiment 3
46
PCA maximizes F1, at the expense of a little diversity
Trade-off between F1 and diversity :: MovieLens :: F1@5
Cataldo Musto, Pasquale Lops, Pierpaolo Basile, Marco de Gemmis, Giovanni Semeraro
Semantics-aware Graph-based Recommender Systems Exploiting Linked Open Data. UMAP 2016, Halifax (Canada). 15.07.2016
Experiment 3
47
Gain Ratio and SVM sacrifice F1,
to induce an higher diversity
Trade-off between F1 and diversity :: MovieLens :: F1@5
Cataldo Musto, Pasquale Lops, Pierpaolo Basile, Marco de Gemmis, Giovanni Semeraro
Semantics-aware Graph-based Recommender Systems Exploiting Linked Open Data. UMAP 2016, Halifax (Canada). 15.07.2016
Experiment 3
48
PageRank obtains a good compromise
between F1 and Diversity
Trade-off between F1 and diversity :: MovieLens :: F1@5
Cataldo Musto, Pasquale Lops, Pierpaolo Basile, Marco de Gemmis, Giovanni Semeraro
Semantics-aware Graph-based Recommender Systems Exploiting Linked Open Data. UMAP 2016, Halifax (Canada). 15.07.2016
Experiment 3
49
Similar outcomes on DBbook
…but more techniques have a good impact
Trade-off between F1 and diversity :: MovieLens :: F1@5
Cataldo Musto, Pasquale Lops, Pierpaolo Basile, Marco de Gemmis, Giovanni Semeraro
Semantics-aware Graph-based Recommender Systems Exploiting Linked Open Data. UMAP 2016, Halifax (Canada). 15.07.2016
Experiment 4
50
Comparison to State of the art
BPRMF (Bayesian Personalized Ranking) [+]
U2U-KNN (User to User CF)
I2I-KNN (Item to Item CF)
POPULAR (Popularity-based baseline)
[+] S. Rendle, C.Freudenthaler, Z. Gantner, L. Schmidt-Thieme: BPR:
Bayesian Personalized Ranking from Implicit Feedback. UAI 2009.
Cataldo Musto, Pasquale Lops, Pierpaolo Basile, Marco de Gemmis, Giovanni Semeraro
Semantics-aware Graph-based Recommender Systems Exploiting Linked Open Data. UMAP 2016, Halifax (Canada). 15.07.2016
Experiment 4
51
Comparison to State of the Art :: MovieLens
50
54
58
62
66
F1@5 F1@10
60,88
54,31
59,16
51,4
59,16
51,78
59,7
52,2
58,35
50,22
I2I-KNN U2U-KNN BPRMF POPULAR PR (G_LOD+PCA)
Cataldo Musto, Pasquale Lops, Pierpaolo Basile, Marco de Gemmis, Giovanni Semeraro
Semantics-aware Graph-based Recommender Systems Exploiting Linked Open Data. UMAP 2016, Halifax (Canada). 15.07.2016
Experiment 4
52
50
54
58
62
66
F1@5 F1@10
60,88
54,31
59,16
51,4
59,16
51,78
59,7
52,2
58,35
50,22
I2I-KNN U2U-KNN BPRMF POPULAR PR (G_LOD+PCA)
PageRank with Priors boosted with LOD
is the best-performing approach
Comparison to State of the Art :: MovieLens
Cataldo Musto, Pasquale Lops, Pierpaolo Basile, Marco de Gemmis, Giovanni Semeraro
Semantics-aware Graph-based Recommender Systems Exploiting Linked Open Data. UMAP 2016, Halifax (Canada). 15.07.2016
Experiment 4
53
50
54
58
62
66
F1@5 F1@10
60,88
54,31
59,16
51,4
59,16
51,78
59,7
52,2
58,35
50,22
I2I-KNN U2U-KNN BPRMF POPULAR PR (G_LOD+PCA)
Even state-of-the-art approaches based on Matrix
Factorization are overcame by our methodology
Comparison to State of the Art :: MovieLens
Cataldo Musto, Pasquale Lops, Pierpaolo Basile, Marco de Gemmis, Giovanni Semeraro
Semantics-aware Graph-based Recommender Systems Exploiting Linked Open Data. UMAP 2016, Halifax (Canada). 15.07.2016
Experiment 4
54
50
55
60
65
70
F1@5 F1@10
64,45
55,4
62,72
52,96
62,63
52,9
62,29
51,93
62,1
51,11
I2I-KNN U2U-KNN BPRMF POPULAR PR (G_LOD+PCA)
Behavior confirmed on DBbook
Comparison to State of the Art :: DBbook
Cataldo Musto, Pasquale Lops, Pierpaolo Basile, Marco de Gemmis, Giovanni Semeraro
Semantics-aware Graph-based Recommender Systems Exploiting Linked Open Data. UMAP 2016, Halifax (Canada). 15.07.2016
Conclusions
55Cataldo Musto, Pasquale Lops, Pierpaolo Basile, Marco de Gemmis, Giovanni Semeraro
Semantics-aware Graph-based Recommender Systems Exploiting Linked Open Data. UMAP 2016, Halifax (Canada). 15.07.2016
Recap
56
Methodolology
1. PageRank with Priors as base algorithm
2. Mapping of the items with nodes in the Linked
Open Data Cloud
3. Expansion of the data points and injection of new
nodes and edges
4. Use of feature selection to automatically select the
most promising properties
INVESTIGATION ABOUT THE EFFECTIVENESS OF LINKED OPEN DATA IN
GRAPH-BASED RECOMMENDER SYSTEMS
Cataldo Musto, Pasquale Lops, Pierpaolo Basile, Marco de Gemmis, Giovanni Semeraro
Semantics-aware Graph-based Recommender Systems Exploiting Linked Open Data. UMAP 2016, Halifax (Canada). 15.07.2016
Lessons Learned
57
Evaluation
1. PageRank with Priors benefit of the injection of data points
coming from the LOD cloud
2. Feature Selection techniques improve the results but need
to be properly tuned, since its usage is not always useful
3. A significant connection between the choice of the feature
selection technique and the maximization of a specific
evaluation metric exists
4. PageRank with Priors boosted with LOD significantly
overcomes state-of-the-art approaches
INVESTIGATION ABOUT THE EFFECTIVENESS OF LINKED OPEN DATA IN
GRAPH-BASED RECOMMENDER SYSTEMS
Cataldo Musto, Pasquale Lops, Pierpaolo Basile, Marco de Gemmis, Giovanni Semeraro
Semantics-aware Graph-based Recommender Systems Exploiting Linked Open Data. UMAP 2016, Halifax (Canada). 15.07.2016
thank you
Cataldo Musto
cataldo.musto@uniba.it
@cataldomusto
http://www.di.uniba.it/~swap
Cataldo Musto, Pasquale Lops, Pierpaolo Basile, Marco de Gemmis, Giovanni Semeraro
Semantics-aware Graph-based Recommender Systems Exploiting Linked Open Data. UMAP 2016, Halifax (Canada). 15.07.2016

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Semantics-aware Graph-based Recommender Systems exploiting Linked Open Data

  • 1. Semantics-aware Graph-based Recommender Systems exploiting Linked Open Data Cataldo Musto, Pasquale Lops, Pierpaolo Basile, Marco de Gemmis Giovanni Semeraro (Università degli Studi di Bari ‘Aldo Moro’, Italy - SWAP Research Group) UMAP 2016 24th Conference on User Modeling, Adaptation and Personalization Halifax (Canada) July 15, 2016
  • 2. 2 Linked Open Data Cataldo Musto, Pasquale Lops, Pierpaolo Basile, Marco de Gemmis, Giovanni Semeraro Semantics-aware Graph-based Recommender Systems Exploiting Linked Open Data. UMAP 2016, Halifax (Canada). 15.07.2016
  • 3. 3 Linked Open Data Methodology to publish, share and link structured data on the Web Definition Cataldo Musto, Pasquale Lops, Pierpaolo Basile, Marco de Gemmis, Giovanni Semeraro Semantics-aware Graph-based Recommender Systems Exploiting Linked Open Data. UMAP 2016, Halifax (Canada). 15.07.2016
  • 4. 4 Linked Open Data Cornerstones 1. 2. Use of RDF to publish data on the Web Re-Use of existing properties to express an agreed semantics and connect data sources Cataldo Musto, Pasquale Lops, Pierpaolo Basile, Marco de Gemmis, Giovanni Semeraro Semantics-aware Graph-based Recommender Systems Exploiting Linked Open Data. UMAP 2016, Halifax (Canada). 15.07.2016
  • 5. 5 Linked Open Data (cloud) What is it? A (large) set of interconnected semantic datasets Cataldo Musto, Pasquale Lops, Pierpaolo Basile, Marco de Gemmis, Giovanni Semeraro Semantics-aware Graph-based Recommender Systems Exploiting Linked Open Data. UMAP 2016, Halifax (Canada). 15.07.2016
  • 6. 6 Linked Open Data (cloud) What kind of datasets? Each bubble is a dataset! Cataldo Musto, Pasquale Lops, Pierpaolo Basile, Marco de Gemmis, Giovanni Semeraro Semantics-aware Graph-based Recommender Systems Exploiting Linked Open Data. UMAP 2016, Halifax (Canada). 15.07.2016
  • 7. 7 Linked Open Data (cloud) How many data? 9960 datasets and 149 billions triplessource: http://stats.lod2.eu today! Cataldo Musto, Pasquale Lops, Pierpaolo Basile, Marco de Gemmis, Giovanni Semeraro Semantics-aware Graph-based Recommender Systems Exploiting Linked Open Data. UMAP 2016, Halifax (Canada). 15.07.2016
  • 8. 8 Linked Open Data (cloud) DBpedia is the structured RDF mapping of Wikipedia http://dbpedia.org It is the core of the LOD cloud. DBpedia Cataldo Musto, Pasquale Lops, Pierpaolo Basile, Marco de Gemmis, Giovanni Semeraro Semantics-aware Graph-based Recommender Systems Exploiting Linked Open Data. UMAP 2016, Halifax (Canada). 15.07.2016
  • 9. 9 Linked Open Data (cloud) Example: unstructured content from Wikipedia example (Wikipedia page) Cataldo Musto, Pasquale Lops, Pierpaolo Basile, Marco de Gemmis, Giovanni Semeraro Semantics-aware Graph-based Recommender Systems Exploiting Linked Open Data. UMAP 2016, Halifax (Canada). 15.07.2016
  • 10. 10 Linked Open Data (cloud) How are these data represented? The Matrix Don Davis http://dbpedia.org/resource/Category:Films_shot_in_Australia Films shot in Australia dcterms:subject dbpedia-owl:m usicCom poser http://dbpedia.org/resource/Don_Davis_(composer) dcterms:subject dcterm s:subject dbo:runtimedbpedia-owl:director dcterm s:subject dcterm s:subject Dystopian Films136 American Action Thriller Films Cyberpunk Films The Wachowskis http://dbpedia.org/resource/The_Wachowskis http://dbpedia.org/resource/Dystopian_FIlms http://dbpedia.org/resource/Cyberpunk_Films http://dbpedia.org/resource/American_Action_Thriller_FIlms http://dbpedia.org/resource/Films_About_Rebellions Films about Rebellions Several interesting (non-trivial) features come into play! Cataldo Musto, Pasquale Lops, Pierpaolo Basile, Marco de Gemmis, Giovanni Semeraro Semantics-aware Graph-based Recommender Systems Exploiting Linked Open Data. UMAP 2016, Halifax (Canada). 15.07.2016
  • 11. 11 Linked Open Data (cloud) How are these data represented? The Matrix Don Davis http://dbpedia.org/resource/Category:Films_shot_in_Australia Films shot in Australia dcterms:subject dbpedia-owl:m usicCom poser http://dbpedia.org/resource/Don_Davis_(composer) dcterms:subject dcterm s:subject dbo:runtimedbpedia-owl:director dcterm s:subject dcterm s:subject Dystopian Films136 American Action Thriller Films Cyberpunk Films The Wachowskis http://dbpedia.org/resource/The_Wachowskis http://dbpedia.org/resource/Dystopian_FIlms http://dbpedia.org/resource/Cyberpunk_Films http://dbpedia.org/resource/American_Action_Thriller_FIlms http://dbpedia.org/resource/Films_About_Rebellions Films about Rebellions Several interesting (non-trivial) features come into play! Cataldo Musto, Pasquale Lops, Pierpaolo Basile, Marco de Gemmis, Giovanni Semeraro Semantics-aware Graph-based Recommender Systems Exploiting Linked Open Data. UMAP 2016, Halifax (Canada). 15.07.2016
  • 12. 12 Research Questions (1) Can we use Linked Open Data for Recommender Systems? Cataldo Musto, Pasquale Lops, Pierpaolo Basile, Marco de Gemmis, Giovanni Semeraro Semantics-aware Graph-based Recommender Systems Exploiting Linked Open Data. UMAP 2016, Halifax (Canada). 15.07.2016
  • 13. 13 Research Questions (2) Is it possible to automatically select the most promising properties among those available in the LOD cloud? Cataldo Musto, Pasquale Lops, Pierpaolo Basile, Marco de Gemmis, Giovanni Semeraro Semantics-aware Graph-based Recommender Systems Exploiting Linked Open Data. UMAP 2016, Halifax (Canada). 15.07.2016
  • 14. 14 i4 u1 u2 u3 u4 Methodology Graph-based Data Model - original representation Original Graph-based data model Users and Items are connected according to users’ preferences Cataldo Musto, Pasquale Lops, Pierpaolo Basile, Marco de Gemmis, Giovanni Semeraro Semantics-aware Graph-based Recommender Systems Exploiting Linked Open Data. UMAP 2016, Halifax (Canada). 15.07.2016
  • 15. 15 i4 u1 u2 u3 u4 Methodology Graph-based Data Model - DBpedia Mapping If we are able to map the items in the dataset with the entities in the LOD cloud, our representation can be extended with new data points Cataldo Musto, Pasquale Lops, Pierpaolo Basile, Marco de Gemmis, Giovanni Semeraro Semantics-aware Graph-based Recommender Systems Exploiting Linked Open Data. UMAP 2016, Halifax (Canada). 15.07.2016
  • 16. 16 i4 u1 u2 u3 u4 dcterms:subject http://dbpedia.org/resource/Films_About_Rebellions Films about Rebellions dbprop:director Quentin Tarantino dbprop:director Methodology Graph-based Data Model - LOD-boosted representation 1999 films http://dbpedia.org/resource/1999_films dcterms:subject dcterms:subject Cataldo Musto, Pasquale Lops, Pierpaolo Basile, Marco de Gemmis, Giovanni Semeraro Semantics-aware Graph-based Recommender Systems Exploiting Linked Open Data. UMAP 2016, Halifax (Canada). 15.07.2016
  • 17. 17 i4 u1 u2 u3 u4 dcterms:subject http://dbpedia.org/resource/Films_About_Rebellions Films about Rebellions dbprop:director Quentin Tarantino dbprop:director Methodology example - LOD-boosted representation 1999 films http://dbpedia.org/resource/1999_films dcterms:subject dcterms:subject Many new information can be injected in the graph Cataldo Musto, Pasquale Lops, Pierpaolo Basile, Marco de Gemmis, Giovanni Semeraro Semantics-aware Graph-based Recommender Systems Exploiting Linked Open Data. UMAP 2016, Halifax (Canada). 15.07.2016
  • 18. 18 i4 u1 u2 u3 u4 dcterms:subject http://dbpedia.org/resource/Films_About_Rebellions Films about Rebellions dbprop:director Quentin Tarantino dbprop:director Methodology example - LOD-boosted representation 1999 films http://dbpedia.org/resource/1999_films dcterms:subject dcterms:subject How to get recommendations? Cataldo Musto, Pasquale Lops, Pierpaolo Basile, Marco de Gemmis, Giovanni Semeraro Semantics-aware Graph-based Recommender Systems Exploiting Linked Open Data. UMAP 2016, Halifax (Canada). 15.07.2016
  • 19. 19 Graph-based Recommendation Algorithm Insight: - Calculate PageRank score for each item node. - Sort PageRank scores in a descending order. - Select top-k recommendations PageRank with Priors . T. H. Haveliwala. Topic-Sensitive PageRank: A Context-Sensitive Ranking Algorithm for Web Search. IEEE Trans. Knowl. Data Eng., 15(4): 784–796, 2003. 
 Reference Cataldo Musto, Pasquale Lops, Pierpaolo Basile, Marco de Gemmis, Giovanni Semeraro Semantics-aware Graph-based Recommender Systems Exploiting Linked Open Data. UMAP 2016, Halifax (Canada). 15.07.2016
  • 20. 20 i4 u1 u2 u3 u4 dcterms:subject http://dbpedia.org/resource/Films_About_Rebellions Films about Rebellions dbprop:director Quentin Tarantino dbprop:director Methodology example - LOD-boosted representation 1999 films http://dbpedia.org/resource/1999_films dcterms:subject dcterms:subject Is it possibile to automatically select the most promising properties? Cataldo Musto, Pasquale Lops, Pierpaolo Basile, Marco de Gemmis, Giovanni Semeraro Semantics-aware Graph-based Recommender Systems Exploiting Linked Open Data. UMAP 2016, Halifax (Canada). 15.07.2016
  • 21. 21 i4 u1 u2 u3 u4 dcterms:subject http://dbpedia.org/resource/Films_About_Rebellions Films about Rebellions dbprop:director Quentin Tarantino dbprop:director Methodology example - LOD-boosted representation 1999 films http://dbpedia.org/resource/1999_films dcterms:subject dcterms:subject X X Cataldo Musto, Pasquale Lops, Pierpaolo Basile, Marco de Gemmis, Giovanni Semeraro Semantics-aware Graph-based Recommender Systems Exploiting Linked Open Data. UMAP 2016, Halifax (Canada). 15.07.2016
  • 22. 22 i4 u1 u2 u3 u4 dcterms:subject http://dbpedia.org/resource/Films_About_Rebellions Films about Rebellions dbprop:director Quentin Tarantino dbprop:director Methodology example - LOD-boosted representation 1999 films http://dbpedia.org/resource/1999_films dcterms:subject dcterms:subject X X X Cataldo Musto, Pasquale Lops, Pierpaolo Basile, Marco de Gemmis, Giovanni Semeraro Semantics-aware Graph-based Recommender Systems Exploiting Linked Open Data. UMAP 2016, Halifax (Canada). 15.07.2016
  • 23. 23 Experiments Cataldo Musto, Pasquale Lops, Pierpaolo Basile, Marco de Gemmis, Giovanni Semeraro Semantics-aware Graph-based Recommender Systems Exploiting Linked Open Data. UMAP 2016, Halifax (Canada). 15.07.2016
  • 24. 24 Research Questions Do graph-based recommender systems benefit of the introduction of LOD-based features? Do graph-based recommender systems exploiting LOD benefit of the adoption of feature selection techniques? 1/2 1. 2. Cataldo Musto, Pasquale Lops, Pierpaolo Basile, Marco de Gemmis, Giovanni Semeraro Semantics-aware Graph-based Recommender Systems Exploiting Linked Open Data. UMAP 2016, Halifax (Canada). 15.07.2016
  • 25. 25 Research Questions 3. 4. 2/2 Is there any correlation between the choice of the FS technique and the behavior of the algorithm? (e.g., better diversity or better F1) ? How does our methodology perform with respect to state-of- the-art algorithms? Cataldo Musto, Pasquale Lops, Pierpaolo Basile, Marco de Gemmis, Giovanni Semeraro Semantics-aware Graph-based Recommender Systems Exploiting Linked Open Data. UMAP 2016, Halifax (Canada). 15.07.2016
  • 26. 26 Experimental Evaluation Description of the dataset MovieLens 100k 983 users 1,682 movies 100,000 ratings 55.17% positive ratings 84.43 ratings/user (avg.) 48.48 ratings/item (avg.) 93.7% sparsity Cataldo Musto, Pasquale Lops, Pierpaolo Basile, Marco de Gemmis, Giovanni Semeraro Semantics-aware Graph-based Recommender Systems Exploiting Linked Open Data. UMAP 2016, Halifax (Canada). 15.07.2016
  • 27. 27 Experimental Evaluation Description of the dataset DBbook dataset 6,181 users 6,733 movies 72,372 ratings 45,85% positive ratings 11.70 ratings/user (avg.) 10.74 ratings/item (avg.) 99.8% sparsity Cataldo Musto, Pasquale Lops, Pierpaolo Basile, Marco de Gemmis, Giovanni Semeraro Semantics-aware Graph-based Recommender Systems Exploiting Linked Open Data. UMAP 2016, Halifax (Canada). 15.07.2016
  • 28. 28 Experimental Evaluation Graph Representations :: Recap G Basic Graph with collaborative data points Cataldo Musto, Pasquale Lops, Pierpaolo Basile, Marco de Gemmis, Giovanni Semeraro Semantics-aware Graph-based Recommender Systems Exploiting Linked Open Data. UMAP 2016, Halifax (Canada). 15.07.2016
  • 29. 29 Experimental Evaluation GLOD Graph extended with all the properties gathered from the LOD cloud Graph Representations :: Recap Cataldo Musto, Pasquale Lops, Pierpaolo Basile, Marco de Gemmis, Giovanni Semeraro Semantics-aware Graph-based Recommender Systems Exploiting Linked Open Data. UMAP 2016, Halifax (Canada). 15.07.2016
  • 30. 30 Experimental Evaluation GLOD+FS Graph encoding only the most relevant properties selected by a feature selection technique FS Graph Representations :: Recap Cataldo Musto, Pasquale Lops, Pierpaolo Basile, Marco de Gemmis, Giovanni Semeraro Semantics-aware Graph-based Recommender Systems Exploiting Linked Open Data. UMAP 2016, Halifax (Canada). 15.07.2016
  • 31. 31 Experimental Evaluation Experimental Protocol Algorithm PageRank with Priors Data Split 5-fold Cross Validation for MovieLens Train/Test for DBbook Graph Representation G, GLOD, GLOD+FS Feature Selection Techniques PageRank, Chi-Square, Information Gain, Gain Ratio, mRMR, PCA, SVM #Selected Features top-10, top-30, top-50 properties Evaluation Metrics F1, Intra-List Diversity, Run Time Cataldo Musto, Pasquale Lops, Pierpaolo Basile, Marco de Gemmis, Giovanni Semeraro Semantics-aware Graph-based Recommender Systems Exploiting Linked Open Data. UMAP 2016, Halifax (Canada). 15.07.2016
  • 32. Experiment 1 32 Impact of LOD-based features. Cataldo Musto, Pasquale Lops, Pierpaolo Basile, Marco de Gemmis, Giovanni Semeraro Semantics-aware Graph-based Recommender Systems Exploiting Linked Open Data. UMAP 2016, Halifax (Canada). 15.07.2016
  • 33. F1@5 F1@10 G G_LOD G G_LOD 53 55 57 59 61 60,83 54,24 60,23 53,89 Experiment 1 33 Impact of LOD-based features :: F1-measure Improvement only on MovieLens F1@5 F1@10 G G_LOD G G_LOD 53 56 59 62 65 64,21 55,04 64,31 55,02 MovieLens DBbook Cataldo Musto, Pasquale Lops, Pierpaolo Basile, Marco de Gemmis, Giovanni Semeraro Semantics-aware Graph-based Recommender Systems Exploiting Linked Open Data. UMAP 2016, Halifax (Canada). 15.07.2016
  • 34. Run Time (min.) G G_LOD 50 262,5 475 687,5 900 880 72 Experiment 1 34 Tremendous increase in the run time Impact of LOD-based features :: Run Time Run Time (min.) G G_LOD 50 662,5 1275 1887,5 2500 2.433 100 MovieLens DBbook Cataldo Musto, Pasquale Lops, Pierpaolo Basile, Marco de Gemmis, Giovanni Semeraro Semantics-aware Graph-based Recommender Systems Exploiting Linked Open Data. UMAP 2016, Halifax (Canada). 15.07.2016
  • 35. Experiment 2 35 Impact of Feature Selection techniques Cataldo Musto, Pasquale Lops, Pierpaolo Basile, Marco de Gemmis, Giovanni Semeraro Semantics-aware Graph-based Recommender Systems Exploiting Linked Open Data. UMAP 2016, Halifax (Canada). 15.07.2016
  • 36. Experiment 2 36 GLOD (baseline) = 54,24 Impact of Feature Selection :: MovieLens :: F1@5 Cataldo Musto, Pasquale Lops, Pierpaolo Basile, Marco de Gemmis, Giovanni Semeraro Semantics-aware Graph-based Recommender Systems Exploiting Linked Open Data. UMAP 2016, Halifax (Canada). 15.07.2016 PageRank mRMR Chi-Square SVM Gain Ratio Inf. Gain PCA 10 30 50 10 30 50 10 30 50 10 30 50 10 30 50 10 30 50 10 30 50 53 53,5 54 54,5 55 54,31 54,12 54,06 54,21 54,2 54,21 54,12 54,13 53,96 53,98 54,13 54,19 54,29 54,29 54,06 53,97 53,72 53,82 54,14 53,97 54,18
  • 37. PageRank mRMR Chi-Square SVM Gain Ratio Inf. Gain PCA 10 30 50 10 30 50 10 30 50 10 30 50 10 30 50 10 30 50 10 30 50 53 53,5 54 54,5 55 54,31 54,12 54,06 54,21 54,2 54,21 54,12 54,13 53,96 53,98 54,13 54,19 54,29 54,29 54,06 53,97 53,72 53,82 54,14 53,97 54,18 Experiment 2 37 Tree out of seven techniques (and only with 50 features) overcome the baseline Impact of Feature Selection :: MovieLens :: F1@5 Cataldo Musto, Pasquale Lops, Pierpaolo Basile, Marco de Gemmis, Giovanni Semeraro Semantics-aware Graph-based Recommender Systems Exploiting Linked Open Data. UMAP 2016, Halifax (Canada). 15.07.2016
  • 38. PageRank mRMR Chi-Square SVM Gain Ratio Inf. Gain PCA 10 30 50 10 30 50 10 30 50 10 30 50 10 30 50 10 30 50 10 30 50 53 53,5 54 54,5 55 54,31 54,12 54,06 54,21 54,2 54,21 54,12 54,13 53,96 53,98 54,13 54,19 54,29 54,29 54,06 53,97 53,72 53,82 54,14 53,97 54,18 Experiment 2 38 Typically, the larger the number of features, the better the F1 #50 #50 #50 #50 #50 #30 #30 (best) Impact of Feature Selection :: MovieLens :: F1@5 Cataldo Musto, Pasquale Lops, Pierpaolo Basile, Marco de Gemmis, Giovanni Semeraro Semantics-aware Graph-based Recommender Systems Exploiting Linked Open Data. UMAP 2016, Halifax (Canada). 15.07.2016
  • 39. PageRank mRMR Chi-Square SVM Gain Ratio Inf. Gain PCA 10 30 50 10 30 50 10 30 50 10 30 50 10 30 50 10 30 50 10 30 50 63,5 63,825 64,15 64,475 64,8 64,286 64,19 64,25 64,26 64,19 64,19 64,18 64,32 64,27 64,31 64,3 64,2 64,27 64,22 64,33 64,45 64,35 64,34 64,23 64,35 64,31 Experiment 2 39 #10 #10 #10 #10 #10 #10 Impact of Feature Selection :: DBbook :: F1@10 #10 GLOD (baseline) = 64,20 Cataldo Musto, Pasquale Lops, Pierpaolo Basile, Marco de Gemmis, Giovanni Semeraro Semantics-aware Graph-based Recommender Systems Exploiting Linked Open Data. UMAP 2016, Halifax (Canada). 15.07.2016
  • 40. PageRank mRMR Chi-Square SVM Gain Ratio Inf. Gain PCA 10 30 50 10 30 50 10 30 50 10 30 50 10 30 50 10 30 50 10 30 50 63,5 63,825 64,15 64,475 64,8 64,286 64,19 64,25 64,26 64,19 64,19 64,18 64,32 64,27 64,31 64,3 64,2 64,27 64,22 64,33 64,45 64,35 64,34 64,23 64,35 64,31 Experiment 2 40 #10 #10 #10 #10 #10 #10 Impact of Feature Selection :: DBbook :: F1@10 #10 All the techniques overcome the baseline at least once Cataldo Musto, Pasquale Lops, Pierpaolo Basile, Marco de Gemmis, Giovanni Semeraro Semantics-aware Graph-based Recommender Systems Exploiting Linked Open Data. UMAP 2016, Halifax (Canada). 15.07.2016
  • 41. PageRank mRMR Chi-Square SVM Gain Ratio Inf. Gain PCA 10 30 50 10 30 50 10 30 50 10 30 50 10 30 50 10 30 50 10 30 50 63,5 63,825 64,15 64,475 64,8 64,286 64,19 64,25 64,26 64,19 64,19 64,18 64,32 64,27 64,31 64,3 64,2 64,27 64,22 64,33 64,45 64,35 64,34 64,23 64,35 64,31 Experiment 2 41 On DBbook best results are obtained with 10 features! #10 #10 #10 #10 #10 #10 (best) Impact of Feature Selection :: DBbook :: F1@10 #10 Cataldo Musto, Pasquale Lops, Pierpaolo Basile, Marco de Gemmis, Giovanni Semeraro Semantics-aware Graph-based Recommender Systems Exploiting Linked Open Data. UMAP 2016, Halifax (Canada). 15.07.2016
  • 42. Run Time (min.) - MovieLens GLOD GLOD+PCA 50 262,5 475 687,5 900 581 880 Experiment 2 42 Significant decrease Impact of Feature Selection techniques :: Run Time Run Time (min.) - DBbook GLOD GLOD+IG 50 687,5 1325 1962,5 2600 1.341 2433 Cataldo Musto, Pasquale Lops, Pierpaolo Basile, Marco de Gemmis, Giovanni Semeraro Semantics-aware Graph-based Recommender Systems Exploiting Linked Open Data. UMAP 2016, Halifax (Canada). 15.07.2016
  • 43. Experiment 3 43 Trade-off between F1 and diversity Cataldo Musto, Pasquale Lops, Pierpaolo Basile, Marco de Gemmis, Giovanni Semeraro Semantics-aware Graph-based Recommender Systems Exploiting Linked Open Data. UMAP 2016, Halifax (Canada). 15.07.2016
  • 44. Experiment 3 44 Trade-off between F1 and diversity Can the choice of the feature selection technique endogenously induce an higher diversity (or, respectively, an higher F1) of the recommendations? Cataldo Musto, Pasquale Lops, Pierpaolo Basile, Marco de Gemmis, Giovanni Semeraro Semantics-aware Graph-based Recommender Systems Exploiting Linked Open Data. UMAP 2016, Halifax (Canada). 15.07.2016
  • 45. Experiment 3 45 Trade-off between F1 and diversity :: MovieLens :: F1@5 G_LOD = Baseline Cataldo Musto, Pasquale Lops, Pierpaolo Basile, Marco de Gemmis, Giovanni Semeraro Semantics-aware Graph-based Recommender Systems Exploiting Linked Open Data. UMAP 2016, Halifax (Canada). 15.07.2016
  • 46. Experiment 3 46 PCA maximizes F1, at the expense of a little diversity Trade-off between F1 and diversity :: MovieLens :: F1@5 Cataldo Musto, Pasquale Lops, Pierpaolo Basile, Marco de Gemmis, Giovanni Semeraro Semantics-aware Graph-based Recommender Systems Exploiting Linked Open Data. UMAP 2016, Halifax (Canada). 15.07.2016
  • 47. Experiment 3 47 Gain Ratio and SVM sacrifice F1, to induce an higher diversity Trade-off between F1 and diversity :: MovieLens :: F1@5 Cataldo Musto, Pasquale Lops, Pierpaolo Basile, Marco de Gemmis, Giovanni Semeraro Semantics-aware Graph-based Recommender Systems Exploiting Linked Open Data. UMAP 2016, Halifax (Canada). 15.07.2016
  • 48. Experiment 3 48 PageRank obtains a good compromise between F1 and Diversity Trade-off between F1 and diversity :: MovieLens :: F1@5 Cataldo Musto, Pasquale Lops, Pierpaolo Basile, Marco de Gemmis, Giovanni Semeraro Semantics-aware Graph-based Recommender Systems Exploiting Linked Open Data. UMAP 2016, Halifax (Canada). 15.07.2016
  • 49. Experiment 3 49 Similar outcomes on DBbook …but more techniques have a good impact Trade-off between F1 and diversity :: MovieLens :: F1@5 Cataldo Musto, Pasquale Lops, Pierpaolo Basile, Marco de Gemmis, Giovanni Semeraro Semantics-aware Graph-based Recommender Systems Exploiting Linked Open Data. UMAP 2016, Halifax (Canada). 15.07.2016
  • 50. Experiment 4 50 Comparison to State of the art BPRMF (Bayesian Personalized Ranking) [+] U2U-KNN (User to User CF) I2I-KNN (Item to Item CF) POPULAR (Popularity-based baseline) [+] S. Rendle, C.Freudenthaler, Z. Gantner, L. Schmidt-Thieme: BPR: Bayesian Personalized Ranking from Implicit Feedback. UAI 2009. Cataldo Musto, Pasquale Lops, Pierpaolo Basile, Marco de Gemmis, Giovanni Semeraro Semantics-aware Graph-based Recommender Systems Exploiting Linked Open Data. UMAP 2016, Halifax (Canada). 15.07.2016
  • 51. Experiment 4 51 Comparison to State of the Art :: MovieLens 50 54 58 62 66 F1@5 F1@10 60,88 54,31 59,16 51,4 59,16 51,78 59,7 52,2 58,35 50,22 I2I-KNN U2U-KNN BPRMF POPULAR PR (G_LOD+PCA) Cataldo Musto, Pasquale Lops, Pierpaolo Basile, Marco de Gemmis, Giovanni Semeraro Semantics-aware Graph-based Recommender Systems Exploiting Linked Open Data. UMAP 2016, Halifax (Canada). 15.07.2016
  • 52. Experiment 4 52 50 54 58 62 66 F1@5 F1@10 60,88 54,31 59,16 51,4 59,16 51,78 59,7 52,2 58,35 50,22 I2I-KNN U2U-KNN BPRMF POPULAR PR (G_LOD+PCA) PageRank with Priors boosted with LOD is the best-performing approach Comparison to State of the Art :: MovieLens Cataldo Musto, Pasquale Lops, Pierpaolo Basile, Marco de Gemmis, Giovanni Semeraro Semantics-aware Graph-based Recommender Systems Exploiting Linked Open Data. UMAP 2016, Halifax (Canada). 15.07.2016
  • 53. Experiment 4 53 50 54 58 62 66 F1@5 F1@10 60,88 54,31 59,16 51,4 59,16 51,78 59,7 52,2 58,35 50,22 I2I-KNN U2U-KNN BPRMF POPULAR PR (G_LOD+PCA) Even state-of-the-art approaches based on Matrix Factorization are overcame by our methodology Comparison to State of the Art :: MovieLens Cataldo Musto, Pasquale Lops, Pierpaolo Basile, Marco de Gemmis, Giovanni Semeraro Semantics-aware Graph-based Recommender Systems Exploiting Linked Open Data. UMAP 2016, Halifax (Canada). 15.07.2016
  • 54. Experiment 4 54 50 55 60 65 70 F1@5 F1@10 64,45 55,4 62,72 52,96 62,63 52,9 62,29 51,93 62,1 51,11 I2I-KNN U2U-KNN BPRMF POPULAR PR (G_LOD+PCA) Behavior confirmed on DBbook Comparison to State of the Art :: DBbook Cataldo Musto, Pasquale Lops, Pierpaolo Basile, Marco de Gemmis, Giovanni Semeraro Semantics-aware Graph-based Recommender Systems Exploiting Linked Open Data. UMAP 2016, Halifax (Canada). 15.07.2016
  • 55. Conclusions 55Cataldo Musto, Pasquale Lops, Pierpaolo Basile, Marco de Gemmis, Giovanni Semeraro Semantics-aware Graph-based Recommender Systems Exploiting Linked Open Data. UMAP 2016, Halifax (Canada). 15.07.2016
  • 56. Recap 56 Methodolology 1. PageRank with Priors as base algorithm 2. Mapping of the items with nodes in the Linked Open Data Cloud 3. Expansion of the data points and injection of new nodes and edges 4. Use of feature selection to automatically select the most promising properties INVESTIGATION ABOUT THE EFFECTIVENESS OF LINKED OPEN DATA IN GRAPH-BASED RECOMMENDER SYSTEMS Cataldo Musto, Pasquale Lops, Pierpaolo Basile, Marco de Gemmis, Giovanni Semeraro Semantics-aware Graph-based Recommender Systems Exploiting Linked Open Data. UMAP 2016, Halifax (Canada). 15.07.2016
  • 57. Lessons Learned 57 Evaluation 1. PageRank with Priors benefit of the injection of data points coming from the LOD cloud 2. Feature Selection techniques improve the results but need to be properly tuned, since its usage is not always useful 3. A significant connection between the choice of the feature selection technique and the maximization of a specific evaluation metric exists 4. PageRank with Priors boosted with LOD significantly overcomes state-of-the-art approaches INVESTIGATION ABOUT THE EFFECTIVENESS OF LINKED OPEN DATA IN GRAPH-BASED RECOMMENDER SYSTEMS Cataldo Musto, Pasquale Lops, Pierpaolo Basile, Marco de Gemmis, Giovanni Semeraro Semantics-aware Graph-based Recommender Systems Exploiting Linked Open Data. UMAP 2016, Halifax (Canada). 15.07.2016
  • 58. thank you Cataldo Musto cataldo.musto@uniba.it @cataldomusto http://www.di.uniba.it/~swap Cataldo Musto, Pasquale Lops, Pierpaolo Basile, Marco de Gemmis, Giovanni Semeraro Semantics-aware Graph-based Recommender Systems Exploiting Linked Open Data. UMAP 2016, Halifax (Canada). 15.07.2016