EC-WEB 2013 - 14th International Conference on Electronic Commerce and Web Technologies Prague (Czech Republich) - 28.08.13 Contextual eVSM: a context-aware content-based recommendation framework based on distributional semantics Cataldo Musto, Giovanni Semeraro, Pasquale Lops, Marco de Gemmis
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Contextual eVSM: a context-aware content-based recommendation framework based on distributional semantics
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EC-WEB 2013 - 14th International Conference on Electronic Commerce and Web Technologies Prague (Czech Republich) - 28.08.13
Contextual eVSM: a context-aware content-based recommendation framework based on
distributional semantics
Cataldo Musto, Giovanni Semeraro, Pasquale Lops, Marco de Gemmis
scenario.
C. Musto, G. Semeraro, P. Lops, M. de Gemmis. - Contextual eVSM: a context-aware content-based recommendation framework based on distributional semantics - EC WEB 2013 - Prague, Czech Republic - 28.08.2013
Prague, EC-Web conferenceC. Musto, G. Semeraro, P. Lops, M. de Gemmis. - Contextual eVSM: a context-aware content-based recommendation framework based on distributional semantics - EC WEB 2013 - Prague, Czech Republic - 28.08.2013
dinner timeC. Musto, G. Semeraro, P. Lops, M. de Gemmis. - Contextual eVSM: a context-aware content-based recommendation framework based on distributional semantics - EC WEB 2013 - Prague, Czech Republic - 28.08.2013
me and Pasquale like sushi.C. Musto, G. Semeraro, P. Lops, M. de Gemmis. - Contextual eVSM: a context-aware content-based recommendation framework based on distributional semantics - EC WEB 2013 - Prague, Czech Republic - 28.08.2013
what does TripAdvisor suggest?
C. Musto, G. Semeraro, P. Lops, M. de Gemmis. - Contextual eVSM: a context-aware content-based recommendation framework based on distributional semantics - EC WEB 2013 - Prague, Czech Republic - 28.08.2013
C. Musto, G. Semeraro, P. Lops, M. de Gemmis. - Contextual eVSM: a context-aware content-based recommendation framework based on distributional semantics - EC WEB 2013 - Prague, Czech Republic - 28.08.2013
Good PriceC. Musto, G. Semeraro, P. Lops, M. de Gemmis. - Contextual eVSM: a context-aware content-based recommendation framework based on distributional semantics - EC WEB 2013 - Prague, Czech Republic - 28.08.2013
Good ReviewsC. Musto, G. Semeraro, P. Lops, M. de Gemmis. - Contextual eVSM: a context-aware content-based recommendation framework based on distributional semantics - EC WEB 2013 - Prague, Czech Republic - 28.08.2013
....Strasbourg?C. Musto, G. Semeraro, P. Lops, M. de Gemmis. - Contextual eVSM: a context-aware content-based recommendation framework based on distributional semantics - EC WEB 2013 - Prague, Czech Republic - 28.08.2013
612 km far away.
C. Musto, G. Semeraro, P. Lops, M. de Gemmis. - Contextual eVSM: a context-aware content-based recommendation framework based on distributional semantics - EC WEB 2013 - Prague, Czech Republic - 28.08.2013
612 km far away.Too much :-)
C. Musto, G. Semeraro, P. Lops, M. de Gemmis. - Contextual eVSM: a context-aware content-based recommendation framework based on distributional semantics - EC WEB 2013 - Prague, Czech Republic - 28.08.2013
we ate pizza, as usual.C. Musto, G. Semeraro, P. Lops, M. de Gemmis. - Contextual eVSM: a context-aware content-based recommendation framework based on distributional semantics - EC WEB 2013 - Prague, Czech Republic - 28.08.2013
why did the TripAdvisor recommendation engine fail?
C. Musto, G. Semeraro, P. Lops, M. de Gemmis. - Contextual eVSM: a context-aware content-based recommendation framework based on distributional semantics - EC WEB 2013 - Prague, Czech Republic - 28.08.2013
it doesn’t take into account contextual information.
context plays a key role in several recommendation tasks.
C. Musto, G. Semeraro, P. Lops, M. de Gemmis. - Contextual eVSM: a context-aware content-based recommendation framework based on distributional semantics - EC WEB 2013 - Prague, Czech Republic - 28.08.2013
C. Musto, G. Semeraro, P. Lops, M. de Gemmis. - Contextual eVSM: a context-aware content-based recommendation framework based on distributional semantics - EC WEB 2013 - Prague, Czech Republic - 28.08.2013
I attended last Sigur Ròs concert in Rome, so I like them
C. Musto, G. Semeraro, P. Lops, M. de Gemmis. - Contextual eVSM: a context-aware content-based recommendation framework based on distributional semantics - EC WEB 2013 - Prague, Czech Republic - 28.08.2013
I attended last Sigur Ròs concert in Rome, so I like them
but their ambient music is not good if I need music recommendation for my running session!
a real-world recommendation engine needs to take into account
contextual information
C. Musto, G. Semeraro, P. Lops, M. de Gemmis. - Contextual eVSM: a context-aware content-based recommendation framework based on distributional semantics - EC WEB 2013 - Prague, Czech Republic - 28.08.2013
what is context?
• Over 150 definitions, spread across several domains (Bazire and Brezillon, 2005)
• Recommender Systems area
• “A set of factors that have influence on user perception and acceptance of a particular item”
• A fixed set of dimensions with appropriate attributes
C. Musto, G. Semeraro, P. Lops, M. de Gemmis. - Contextual eVSM: a context-aware content-based recommendation framework based on distributional semantics - EC WEB 2013 - Prague, Czech Republic - 28.08.2013
what is context?
C. Musto, G. Semeraro, P. Lops, M. de Gemmis. - Contextual eVSM: a context-aware content-based recommendation framework based on distributional semantics - EC WEB 2013 - Prague, Czech Republic - 28.08.2013
task
what is context?
C. Musto, G. Semeraro, P. Lops, M. de Gemmis. - Contextual eVSM: a context-aware content-based recommendation framework based on distributional semantics - EC WEB 2013 - Prague, Czech Republic - 28.08.2013
task
what is context?
C. Musto, G. Semeraro, P. Lops, M. de Gemmis. - Contextual eVSM: a context-aware content-based recommendation framework based on distributional semantics - EC WEB 2013 - Prague, Czech Republic - 28.08.2013
task company
what is context?
C. Musto, G. Semeraro, P. Lops, M. de Gemmis. - Contextual eVSM: a context-aware content-based recommendation framework based on distributional semantics - EC WEB 2013 - Prague, Czech Republic - 28.08.2013
task company
what is context?
C. Musto, G. Semeraro, P. Lops, M. de Gemmis. - Contextual eVSM: a context-aware content-based recommendation framework based on distributional semantics - EC WEB 2013 - Prague, Czech Republic - 28.08.2013
task moodcompany
what is context?
C. Musto, G. Semeraro, P. Lops, M. de Gemmis. - Contextual eVSM: a context-aware content-based recommendation framework based on distributional semantics - EC WEB 2013 - Prague, Czech Republic - 28.08.2013
task company mood
a real-world recommendation engine needs to take into account
contextual information
C. Musto, G. Semeraro, P. Lops, M. de Gemmis. - Contextual eVSM: a context-aware content-based recommendation framework based on distributional semantics - EC WEB 2013 - Prague, Czech Republic - 28.08.2013
C. Musto, G. Semeraro, P. Lops, M. de Gemmis. - Contextual eVSM: a context-aware content-based recommendation framework based on distributional semantics - EC WEB 2013 - Prague, Czech Republic - 28.08.2013
(*) Cataldo Musto: Enhanced vector space models for content-based recommender systems. RecSys 2010: 361-364
C. Musto, G. Semeraro, P. Lops, M. de Gemmis. - Contextual eVSM: a context-aware content-based recommendation framework based on distributional semantics - EC WEB 2013 - Prague, Czech Republic - 28.08.2013
C. Musto, G. Semeraro, P. Lops, M. de Gemmis. - Contextual eVSM: a context-aware content-based recommendation framework based on distributional semantics - EC WEB 2013 - Prague, Czech Republic - 28.08.2013
eVSMa brief recap
eVSM
• Content-based Recommendation Framework
• (semantic) vector space representation based on distributional models
• negative information modeled through quantum negation operator
• recommendation seen as a form of similarity in vector spaces
• four different profiling models
• cosine similarity to get the top-k recommendations
C. Musto, G. Semeraro, P. Lops, M. de Gemmis. - Contextual eVSM: a context-aware content-based recommendation framework based on distributional semantics - EC WEB 2013 - Prague, Czech Republic - 28.08.2013
cornerstones
distributional models(Firth, 1957)
Firth, J.R. A synopsis of linguistic theory 1930-1955. In Studies in Linguistic Analysis, pp. 1-32, 1957.
C. Musto, G. Semeraro, P. Lops, M. de Gemmis. - Contextual eVSM: a context-aware content-based recommendation framework based on distributional semantics - EC WEB 2013 - Prague, Czech Republic - 28.08.2013
cornerstone 1
“meaning is its use”
L.Wittgenstein(Austrian philosopher)
distributional semantics
C. Musto, G. Semeraro, P. Lops, M. de Gemmis. - Contextual eVSM: a context-aware content-based recommendation framework based on distributional semantics - EC WEB 2013 - Prague, Czech Republic - 28.08.2013
insightby analyzing large corpus of textual data it is possible to infer information about the usage (about the meaning) of the terms.example
distributional models
C. Musto, G. Semeraro, P. Lops, M. de Gemmis. - Contextual eVSM: a context-aware content-based recommendation framework based on distributional semantics - EC WEB 2013 - Prague, Czech Republic - 28.08.2013
distributional hypothesis
C. Musto, G. Semeraro, P. Lops, M. de Gemmis. - Contextual eVSM: a context-aware content-based recommendation framework based on distributional semantics - EC WEB 2013 - Prague, Czech Republic - 28.08.2013
“terms that occur in similar contexts share a similar meaning”
distributional models
c1 c2 c3 c4 c5 c6
rock ✔ ✔ ✔
post rock ✔ ✔
jazz ✔
classical ✔ ✔ ✔
term/context matrix (WordSpace)
C. Musto, G. Semeraro, P. Lops, M. de Gemmis. - Contextual eVSM: a context-aware content-based recommendation framework based on distributional semantics - EC WEB 2013 - Prague, Czech Republic - 28.08.2013
distributional modelsrock vs. post rock = good overlap
c1 c2 c3 c4 c5 c6
rock ✔ ✔ ✔
post rock ✔ ✔
jazz ✔
classical ✔ ✔ ✔
C. Musto, G. Semeraro, P. Lops, M. de Gemmis. - Contextual eVSM: a context-aware content-based recommendation framework based on distributional semantics - EC WEB 2013 - Prague, Czech Republic - 28.08.2013
distributional modelsrock vs. classical = no overlap
c1 c2 c3 c4 c5 c6
rock ✔ ✔ ✔
post rock ✔ ✔
jazz ✔
classical ✔ ✔ ✔
C. Musto, G. Semeraro, P. Lops, M. de Gemmis. - Contextual eVSM: a context-aware content-based recommendation framework based on distributional semantics - EC WEB 2013 - Prague, Czech Republic - 28.08.2013
• Key: definition of what is the ‘context’
• Different granularities are possible
• Document
• Paragraph
• Sentence
• Sliding window of words
distributional models
C. Musto, G. Semeraro, P. Lops, M. de Gemmis. - Contextual eVSM: a context-aware content-based recommendation framework based on distributional semantics - EC WEB 2013 - Prague, Czech Republic - 28.08.2013
rockalternative-rock
post-rock
classical
exampleWordSpace
C. Musto, G. Semeraro, P. Lops, M. de Gemmis. - Contextual eVSM: a context-aware content-based recommendation framework based on distributional semantics - EC WEB 2013 - Prague, Czech Republic - 28.08.2013
representation of documents (*) can be inferred by combining the representation of the terms (**) occurring in the document.
(*) documents = artists(**) terms = tags
C. Musto, G. Semeraro, P. Lops, M. de Gemmis. - Contextual eVSM: a context-aware content-based recommendation framework based on distributional semantics - EC WEB 2013 - Prague, Czech Republic - 28.08.2013
distributional models
c1 c2 c3 c4 c5 c6 c7 c8 c9
t2 ✔ ✔ ✔ ✔
t3 ✔ ✔ ✔
d1 ✔ ✔ ✔ ✔ ✔
term/context matrix (DocSpace)
C. Musto, G. Semeraro, P. Lops, M. de Gemmis. - Contextual eVSM: a context-aware content-based recommendation framework based on distributional semantics - EC WEB 2013 - Prague, Czech Republic - 28.08.2013
Coldplay
RadioheadKings of Leon
Lady Gaga
exampleDocSpace
C. Musto, G. Semeraro, P. Lops, M. de Gemmis. - Contextual eVSM: a context-aware content-based recommendation framework based on distributional semantics - EC WEB 2013 - Prague, Czech Republic - 28.08.2013
distributional models
• Features
• semantic vector space representation of terms and documents (user profiles and items !)
• light semantics, based on term co-occurrences in large corpus of data
• based on distributional hypothesis
• totally unsupervised
• just based on the analysis of term distribution
C. Musto, G. Semeraro, P. Lops, M. de Gemmis. - Contextual eVSM: a context-aware content-based recommendation framework based on distributional semantics - EC WEB 2013 - Prague, Czech Republic - 28.08.2013
quantum negation(Widdows, 2007)
cornerstone 2
C. Musto, G. Semeraro, P. Lops, M. de Gemmis. - Contextual eVSM: a context-aware content-based recommendation framework based on distributional semantics - EC WEB 2013 - Prague, Czech Republic - 28.08.2013
negation in VSMs
•Widdows proposed a different point of view
• Negation view as a form of orthogonality between vectors
• Vision inherited from Quantum Logic
state of the art
C. Musto, G. Semeraro, P. Lops, M. de Gemmis. - Contextual eVSM: a context-aware content-based recommendation framework based on distributional semantics - EC WEB 2013 - Prague, Czech Republic - 28.08.2013
negation in VSMs
• Some theory
• Given vector a and vector b• Through quantum negation it is possible to define a
vector a not b (a ∧¬b)
• Projection of vector a on the subspace
orthogonal to those generated by vector b
Quantum Negation
C. Musto, G. Semeraro, P. Lops, M. de Gemmis. - Contextual eVSM: a context-aware content-based recommendation framework based on distributional semantics - EC WEB 2013 - Prague, Czech Republic - 28.08.2013
negation in VSMs
• Two terms can be considered as mutually unrelevant if they never co-occur
• Two documents can be considered as mutually unrelevant if they have no features in common
• No features in common ⇒ scalar product = 0
•Orthogonality
Widdows’ insights
C. Musto, G. Semeraro, P. Lops, M. de Gemmis. - Contextual eVSM: a context-aware content-based recommendation framework based on distributional semantics - EC WEB 2013 - Prague, Czech Republic - 28.08.2013
quantum negation
• Vector A models positive feedbacks
• Information about what a user likes
• Vector B models negative feedbacks
• Information about what a user does not like
• Vector A not B combines both information sources
application to CBRS
C. Musto, G. Semeraro, P. Lops, M. de Gemmis. - Contextual eVSM: a context-aware content-based recommendation framework based on distributional semantics - EC WEB 2013 - Prague, Czech Republic - 28.08.2013
recommendation step
C. Musto, G. Semeraro, P. Lops, M. de Gemmis. - Contextual eVSM: a context-aware content-based recommendation framework based on distributional semantics - EC WEB 2013 - Prague, Czech Republic - 28.08.2013
cornerstone 3
ThresholdRatingItems
Higher weight given to the documents with higher rating
User ProfilesWeighted Random Indexing-based (w-RI)
C. Musto, G. Semeraro, P. Lops, M. de Gemmis. - Contextual eVSM: a context-aware content-based recommendation framework based on distributional semantics - EC WEB 2013 - Prague, Czech Republic - 28.08.2013
VSM representation of wQN-based profile for user u
Positive User Profile Vector
Negative User Profile Vector
User ProfilesWeighted Quantum Negation-based (w-QN)
C. Musto, G. Semeraro, P. Lops, M. de Gemmis. - Contextual eVSM: a context-aware content-based recommendation framework based on distributional semantics - EC WEB 2013 - Prague, Czech Republic - 28.08.2013
scenario
football news
sports news
politics news
politics news
user profile
Recommendation task seen as similarity
calculation between vectors
C. Musto, G. Semeraro, P. Lops, M. de Gemmis. - Contextual eVSM: a context-aware content-based recommendation framework based on distributional semantics - EC WEB 2013 - Prague, Czech Republic - 28.08.2013
scenario
football news
sports news
politics news
politics news
user profile
football and sports news are recommended to
the target user
C. Musto, G. Semeraro, P. Lops, M. de Gemmis. - Contextual eVSM: a context-aware content-based recommendation framework based on distributional semantics - EC WEB 2013 - Prague, Czech Republic - 28.08.2013
size=400 - Movielens dataset
Gap always around 1%
84
84,75
85,5
86,25
87
p@1 P@3 P@5 P@10
84,7584,7
84,97
85,39
84,5884,7
84,85
85,27
84,5
84,77
84,4384,47
85,5285,58
86,0185,94eVSM VSMLSI Bayes
experiment(*)
Cataldo Musto - Enhanced Vector Space Models for Content-based Recommender Systems - Ph.D. defense - University of Bari Aldo Moro, Italy - 08.06.12
(*) Cataldo Musto. Enhanced Vector Space Models for content-based Recommender Systems. Ph.D dissertation, 2012
84
84,75
85,5
86,25
87
p@1 P@3 P@5 P@10
84,7584,7
84,97
85,39
84,5884,7
84,85
85,27
84,5
84,77
84,4384,47
85,5285,58
86,0185,94eVSM VSMLSI Bayes
size=400 - Movielens dataset
Significant Improvement
Cataldo Musto - Enhanced Vector Space Models for Content-based Recommender Systems - Ph.D. defense - University of Bari Aldo Moro, Italy - 08.06.12
experiment(*) (*) Cataldo Musto. Enhanced Vector Space Models for content-based Recommender Systems. Ph.D dissertation, 2012
eVSM outperforms other state-of-the-art approaches
C. Musto, G. Semeraro, P. Lops, M. de Gemmis. - Contextual eVSM: a context-aware content-based recommendation framework based on distributional semantics - EC WEB 2013 - Prague, Czech Republic - 28.08.2013
eVSM outperforms other state-of-the-art approaches
C. Musto, G. Semeraro, P. Lops, M. de Gemmis. - Contextual eVSM: a context-aware content-based recommendation framework based on distributional semantics - EC WEB 2013 - Prague, Czech Republic - 28.08.2013
but it doesn’t take into account contextual information.
contextual eVSM
C. Musto, G. Semeraro, P. Lops, M. de Gemmis. - Contextual eVSM: a context-aware content-based recommendation framework based on distributional semantics - EC WEB 2013 - Prague, Czech Republic - 28.08.2013
how to make the eVSM context-aware?
context-aware RSs
C. Musto, G. Semeraro, P. Lops, M. de Gemmis. - Contextual eVSM: a context-aware content-based recommendation framework based on distributional semantics - EC WEB 2013 - Prague, Czech Republic - 28.08.2013
state of the art: pre and post-filtering
we implemented two contextualization strategies
C. Musto, G. Semeraro, P. Lops, M. de Gemmis. - Contextual eVSM: a context-aware content-based recommendation framework based on distributional semantics - EC WEB 2013 - Prague, Czech Republic - 28.08.2013
both pre and post-filtering
context-aware eVSM
•Microprofiling
•based on contextual pre-filtering
• Insight: to filter data before building user profiles, building a separate user profile for each contextual dimension
C. Musto, G. Semeraro, P. Lops, M. de Gemmis. - Contextual eVSM: a context-aware content-based recommendation framework based on distributional semantics - EC WEB 2013 - Prague, Czech Republic - 28.08.2013
context-aware eVSM
•Contextual eVSM
•based on contextual post-filtering
•Insight: to calculate un-contextualized recommendation and to re-rank them according to contextual constraints
C. Musto, G. Semeraro, P. Lops, M. de Gemmis. - Contextual eVSM: a context-aware content-based recommendation framework based on distributional semantics - EC WEB 2013 - Prague, Czech Republic - 28.08.2013
C. Musto, G. Semeraro, P. Lops, M. de Gemmis. - Contextual eVSM: a context-aware content-based recommendation framework based on distributional semantics - EC WEB 2013 - Prague, Czech Republic - 28.08.2013
if a user needs suggestions for a restaurant for a romantic dinner, only her ratings expressed for previous romantic dinners have to be taken
into account
micro-profilinginsight
C. Musto, G. Semeraro, P. Lops, M. de Gemmis. - Contextual eVSM: a context-aware content-based recommendation framework based on distributional semantics - EC WEB 2013 - Prague, Czech Republic - 28.08.2013
micro-profilingcontext-aware eVSM
C. Musto, G. Semeraro, P. Lops, M. de Gemmis. - Contextual eVSM: a context-aware content-based recommendation framework based on distributional semantics - EC WEB 2013 - Prague, Czech Republic - 28.08.2013
micro-profilingcontext-aware eVSM
user
C. Musto, G. Semeraro, P. Lops, M. de Gemmis. - Contextual eVSM: a context-aware content-based recommendation framework based on distributional semantics - EC WEB 2013 - Prague, Czech Republic - 28.08.2013
micro-profilingcontext-aware eVSM
contextual dimension (e.g task)and value (e.g. running)
C. Musto, G. Semeraro, P. Lops, M. de Gemmis. - Contextual eVSM: a context-aware content-based recommendation framework based on distributional semantics - EC WEB 2013 - Prague, Czech Republic - 28.08.2013
micro-profilingcontext-aware eVSM
sum over all the items rated under that specific contextual constraints
C. Musto, G. Semeraro, P. Lops, M. de Gemmis. - Contextual eVSM: a context-aware content-based recommendation framework based on distributional semantics - EC WEB 2013 - Prague, Czech Republic - 28.08.2013
micro-profilingcontext-aware eVSM
weighted with the (normalized) rating provided by the user
contextual eVSM insight
C. Musto, G. Semeraro, P. Lops, M. de Gemmis. - Contextual eVSM: a context-aware content-based recommendation framework based on distributional semantics - EC WEB 2013 - Prague, Czech Republic - 28.08.2013
context is just a factor that can (positively or negatively) influence user preference on a certain item
contextual eVSM insight
C. Musto, G. Semeraro, P. Lops, M. de Gemmis. - Contextual eVSM: a context-aware content-based recommendation framework based on distributional semantics - EC WEB 2013 - Prague, Czech Republic - 28.08.2013
context is just a factor that can (positively or negatively) influence user preference on a certain item
context-aware recommendation can be obtained by combining an uncontextual user profile with a
vector space representation of the target context
C. Musto, G. Semeraro, P. Lops, M. de Gemmis. - Contextual eVSM: a context-aware content-based recommendation framework based on distributional semantics - EC WEB 2013 - Prague, Czech Republic - 28.08.2013
contextual eVSMcontext-aware eVSM
C. Musto, G. Semeraro, P. Lops, M. de Gemmis. - Contextual eVSM: a context-aware content-based recommendation framework based on distributional semantics - EC WEB 2013 - Prague, Czech Republic - 28.08.2013
contextual eVSMcontext-aware eVSM
user profile is the combination of two components
C. Musto, G. Semeraro, P. Lops, M. de Gemmis. - Contextual eVSM: a context-aware content-based recommendation framework based on distributional semantics - EC WEB 2013 - Prague, Czech Republic - 28.08.2013
contextual eVSMcontext-aware eVSM
(1) uncontextual user profile
C. Musto, G. Semeraro, P. Lops, M. de Gemmis. - Contextual eVSM: a context-aware content-based recommendation framework based on distributional semantics - EC WEB 2013 - Prague, Czech Republic - 28.08.2013
contextual eVSMcontext-aware eVSM
(2) vector space representation of the context
C. Musto, G. Semeraro, P. Lops, M. de Gemmis. - Contextual eVSM: a context-aware content-based recommendation framework based on distributional semantics - EC WEB 2013 - Prague, Czech Republic - 28.08.2013
contextual eVSMcontext-aware eVSM
weight of each component
C. Musto, G. Semeraro, P. Lops, M. de Gemmis. - Contextual eVSM: a context-aware content-based recommendation framework based on distributional semantics - EC WEB 2013 - Prague, Czech Republic - 28.08.2013
contextual eVSMcontext-aware eVSM
if alpha = 1, we have uncontextual recommendation since context weight = 0 !
C. Musto, G. Semeraro, P. Lops, M. de Gemmis. - Contextual eVSM: a context-aware content-based recommendation framework based on distributional semantics - EC WEB 2013 - Prague, Czech Republic - 28.08.2013
contextual eVSMcontext-aware eVSM
problem: how to build it ?
• For each contextual dimension, it exists a set of terms that is descriptive of items relevant in that specific context
C. Musto, G. Semeraro, P. Lops, M. de Gemmis. - Contextual eVSM: a context-aware content-based recommendation framework based on distributional semantics - EC WEB 2013 - Prague, Czech Republic - 28.08.2013
context representationassumptions
• For each contextual dimension, it exists a set of terms that is descriptive of items relevant in that specific context
• e.g. candlelight or seaview are relevant features if I’m looking for a restaurant for a romantic night !
C. Musto, G. Semeraro, P. Lops, M. de Gemmis. - Contextual eVSM: a context-aware content-based recommendation framework based on distributional semantics - EC WEB 2013 - Prague, Czech Republic - 28.08.2013
context representationassumptions
C. Musto, G. Semeraro, P. Lops, M. de Gemmis. - Contextual eVSM: a context-aware content-based recommendation framework based on distributional semantics - EC WEB 2013 - Prague, Czech Republic - 28.08.2013
context representationidea
to represent the context as the combination of the terms occurring in the descriptions of the items labeled as relevant under that specific contextual situation
C. Musto, G. Semeraro, P. Lops, M. de Gemmis. - Contextual eVSM: a context-aware content-based recommendation framework based on distributional semantics - EC WEB 2013 - Prague, Czech Republic - 28.08.2013
context representationformula
PRE-WRI is exactly the combination of the terms occurring in the descriptions of the items labeled as relevant under that specific contextual situation !
we adopted PRE-WRI as vector space representation of the context
C. Musto, G. Semeraro, P. Lops, M. de Gemmis. - Contextual eVSM: a context-aware content-based recommendation framework based on distributional semantics - EC WEB 2013 - Prague, Czech Republic - 28.08.2013
rationalecontextual eVSM
if the user didn’t express any preference in that specific context, the vector is null, so she will receive
uncontextual recommendation
C. Musto, G. Semeraro, P. Lops, M. de Gemmis. - Contextual eVSM: a context-aware content-based recommendation framework based on distributional semantics - EC WEB 2013 - Prague, Czech Republic - 28.08.2013
rationalecontextual eVSM
if the user didn’t express any preference in that specific context, the vector is null, so she will receive
uncontextual recommendationotherwise, a greater weight will be given to the
features that are informative and relevant in the target context, that is to say, those contained in the
context vector!
experimental evaluation.
C. Musto, G. Semeraro, P. Lops, M. de Gemmis. - Contextual eVSM: a context-aware content-based recommendation framework based on distributional semantics - EC WEB 2013 - Prague, Czech Republic - 28.08.2013
• Experiments
• (1) Does contextual eVSM outperform eVSM ?
• (2) How does our approach performs with respect to current literature?
experimental design
C. Musto, G. Semeraro, P. Lops, M. de Gemmis. - Contextual eVSM: a context-aware content-based recommendation framework based on distributional semantics - EC WEB 2013 - Prague, Czech Republic - 28.08.2013
•Movie recommendation (IMDB data)
• 202 movies (textual features crawled from Wikipedia)
• 62 users and 1457 ratings
• 4 contextual dimensions
• TIME (weekend, weekday)
• PLACE (theather, home)
• COMPANION (alone, friends, boyfriend, family)
• MOVIE-RELATED (release week or not)
experimental designdataset
C. Musto, G. Semeraro, P. Lops, M. de Gemmis. - Contextual eVSM: a context-aware content-based recommendation framework based on distributional semantics - EC WEB 2013 - Prague, Czech Republic - 28.08.2013
• Dataset and experimental settings replicate Adomavicius’ experiment (*)
• Evaluation over 9 different contextual settings
• Home, Friends, Non-release, Weekend, Weekday, GBFriends, TheatherWeekend and TheatherFriends
• Experimental protocol: bootstrapping
• 29/30th of the data as training
• 1/30th as test
• Randomly generated, 500 runs
experimental designsettings
C. Musto, G. Semeraro, P. Lops, M. de Gemmis. - Contextual eVSM: a context-aware content-based recommendation framework based on distributional semantics - EC WEB 2013 - Prague, Czech Republic - 28.08.2013
(*) G.Adomavicius et al. , Incorporating contextual
C. Musto, G. Semeraro, P. Lops, M. de Gemmis. - Contextual eVSM: a context-aware content-based recommendation framework based on distributional semantics - EC WEB 2013 - Prague, Czech Republic - 28.08.2013
experiment 1selection of results - HOME segment
WRI
PRE-WRI
CONT-WRI-0.5
CONT-WRI-0.8
WQN
PRE-WQN
CONT-WQN-0.5
CONT-WQN-0.8
45 48,75 52,5 56,25 60
pre-filtering outperforms the baseline (it’s an exception, in the other segments it doesn’t !)
C. Musto, G. Semeraro, P. Lops, M. de Gemmis. - Contextual eVSM: a context-aware content-based recommendation framework based on distributional semantics - EC WEB 2013 - Prague, Czech Republic - 28.08.2013
experiment 1selection of results - HOME segment
WRI
PRE-WRI
CONT-WRI-0.5
CONT-WRI-0.8
WQN
PRE-WQN
CONT-WQN-0.5
CONT-WQN-0.8
45 48,75 52,5 56,25 60
contextual eVSM improves the F1 measureC. Musto, G. Semeraro, P. Lops, M. de Gemmis. - Contextual eVSM: a context-aware content-based recommendation framework based on distributional semantics - EC WEB 2013 - Prague, Czech Republic - 28.08.2013
experiment 1selection of results - HOME segment
WRI
PRE-WRI
CONT-WRI-0.5
CONT-WRI-0.8
WQN
PRE-WQN
CONT-WQN-0.5
CONT-WQN-0.8
45 48,75 52,5 56,25 60
alpha=0.8 better than alpha 0.5C. Musto, G. Semeraro, P. Lops, M. de Gemmis. - Contextual eVSM: a context-aware content-based recommendation framework based on distributional semantics - EC WEB 2013 - Prague, Czech Republic - 28.08.2013
experiment 1selection of results - HOME segment
WRI
PRE-WRI
CONT-WRI-0.5
CONT-WRI-0.8
WQN
PRE-WQN
CONT-WQN-0.5
CONT-WQN-0.8
45 48,75 52,5 56,25 60
contextual eVSM with negation is the best settingC. Musto, G. Semeraro, P. Lops, M. de Gemmis. - Contextual eVSM: a context-aware content-based recommendation framework based on distributional semantics - EC WEB 2013 - Prague, Czech Republic - 28.08.2013
experiment 1selection of results - FRIEND segment
WRI
PRE-WRI
CONT-WRI-0.5
CONT-WRI-0.8
WQN
PRE-WQN
CONT-WQN-0.5
CONT-WQN-0.8
45 47,5 50 52,5 55
similar outcomes
C. Musto, G. Semeraro, P. Lops, M. de Gemmis. - Contextual eVSM: a context-aware content-based recommendation framework based on distributional semantics - EC WEB 2013 - Prague, Czech Republic - 28.08.2013
experiment 1selection of results - FRIEND segment
WRI
PRE-WRI
CONT-WRI-0.5
CONT-WRI-0.8
WQN
PRE-WQN
CONT-WQN-0.5
CONT-WQN-0.8
45 47,5 50 52,5 55
pre-filtering doesn’t improve the accuracyC. Musto, G. Semeraro, P. Lops, M. de Gemmis. - Contextual eVSM: a context-aware content-based recommendation framework based on distributional semantics - EC WEB 2013 - Prague, Czech Republic - 28.08.2013
experiment 1selection of results - FRIEND segment
WRI
PRE-WRI
CONT-WRI-0.5
CONT-WRI-0.8
WQN
PRE-WQN
CONT-WQN-0.5
CONT-WQN-0.8
45 47,5 50 52,5 55
contextual eVSM generally does
C. Musto, G. Semeraro, P. Lops, M. de Gemmis. - Contextual eVSM: a context-aware content-based recommendation framework based on distributional semantics - EC WEB 2013 - Prague, Czech Republic - 28.08.2013
experiment 1selection of results - FRIEND segment
WRI
PRE-WRI
CONT-WRI-0.5
CONT-WRI-0.8
WQN
PRE-WQN
CONT-WQN-0.5
CONT-WQN-0.8
45 47,5 50 52,5 55
contextual eVSM with negation and alpha=0.8 is always the best setting
C. Musto, G. Semeraro, P. Lops, M. de Gemmis. - Contextual eVSM: a context-aware content-based recommendation framework based on distributional semantics - EC WEB 2013 - Prague, Czech Republic - 28.08.2013
experiment 1selection of results - NON RELEASE segment
WRI
PRE-WRI
CONT-WRI-0.5
CONT-WRI-0.8
WQN
PRE-WQN
CONT-WQN-0.5
CONT-WQN-0.8
45 48 51 54 57
contextual eVSM with negation and alpha=0.8 is always the best setting
C. Musto, G. Semeraro, P. Lops, M. de Gemmis. - Contextual eVSM: a context-aware content-based recommendation framework based on distributional semantics - EC WEB 2013 - Prague, Czech Republic - 28.08.2013
experiment 1selection of results - NON RELEASE segment
WRI
PRE-WRI
CONT-WRI-0.5
CONT-WRI-0.8
WQN
PRE-WQN
CONT-WQN-0.5
CONT-WQN-0.8
45 48 51 54 57
typically, alpha=0.8 is better than alpha 0.5
C. Musto, G. Semeraro, P. Lops, M. de Gemmis. - Contextual eVSM: a context-aware content-based recommendation framework based on distributional semantics - EC WEB 2013 - Prague, Czech Republic - 28.08.2013
experiment 1selection of results - NON RELEASE segment
WRI
PRE-WRI
CONT-WRI-0.5
CONT-WRI-0.8
WQN
PRE-WQN
CONT-WQN-0.5
CONT-WQN-0.8
45 48 51 54 57
outcome: context has just a little influence on user perception and acceptance. Uncontextual preferences are still the “core”.
C. Musto, G. Semeraro, P. Lops, M. de Gemmis. - Contextual eVSM: a context-aware content-based recommendation framework based on distributional semantics - EC WEB 2013 - Prague, Czech Republic - 28.08.2013
experiment 1selection of results - NON RELEASE segment
WRI
PRE-WRI
CONT-WRI-0.5
CONT-WRI-0.8
WQN
PRE-WQN
CONT-WQN-0.5
CONT-WQN-0.8
45 48 51 54 57
outcome: context has to be taken into account, but just a little!
C. Musto, G. Semeraro, P. Lops, M. de Gemmis. - Contextual eVSM: a context-aware content-based recommendation framework based on distributional semantics - EC WEB 2013 - Prague, Czech Republic - 28.08.2013
experiment 1selection of results - THEATHER segment
WRI
PRE-WRI
CONT-WRI-0.5
CONT-WRI-0.8
WQN
PRE-WQN
CONT-WQN-0.5
CONT-WQN-0.8
45 47,25 49,5 51,75 54
However, in some setting contextual eVSM without negation is the best
C. Musto, G. Semeraro, P. Lops, M. de Gemmis. - Contextual eVSM: a context-aware content-based recommendation framework based on distributional semantics - EC WEB 2013 - Prague, Czech Republic - 28.08.2013
experiment 1selection of results - THEATHER segment
WRI
PRE-WRI
CONT-WRI-0.5
CONT-WRI-0.8
WQN
PRE-WQN
CONT-WQN-0.5
CONT-WQN-0.8
45 47,25 49,5 51,75 54
experiments showed a clear relationship between the amount of negative ratings and the best configurations
C. Musto, G. Semeraro, P. Lops, M. de Gemmis. - Contextual eVSM: a context-aware content-based recommendation framework based on distributional semantics - EC WEB 2013 - Prague, Czech Republic - 28.08.2013
experiment 1selection of results - THEATHER segment
WRI
PRE-WRI
CONT-WRI-0.5
CONT-WRI-0.8
WQN
PRE-WQN
CONT-WQN-0.5
CONT-WQN-0.8
45 47,25 49,5 51,75 54
when the dataset is well balanced, cont-WQN outperforms cont-WRI, otherwise when few negative data are available, cont-WRI is the best
C. Musto, G. Semeraro, P. Lops, M. de Gemmis. - Contextual eVSM: a context-aware content-based recommendation framework based on distributional semantics - EC WEB 2013 - Prague, Czech Republic - 28.08.2013
experiment 1selection of results - THEATHER+FRIENDS segment
WRI
PRE-WRI
CONT-WRI-0.5
CONT-WRI-0.8
WQN
PRE-WQN
CONT-WQN-0.5
CONT-WQN-0.8
40 41,75 43,5 45,25 47
contextual eVSM didn’t improve F1 measure in just 1 contextual segment out of 9
C. Musto, G. Semeraro, P. Lops, M. de Gemmis. - Contextual eVSM: a context-aware content-based recommendation framework based on distributional semantics - EC WEB 2013 - Prague, Czech Republic - 28.08.2013
experiment 1 - outcomecontextual eVSM improves the predictive accuracy of eVSM
C. Musto, G. Semeraro, P. Lops, M. de Gemmis. - Contextual eVSM: a context-aware content-based recommendation framework based on distributional semantics - EC WEB 2013 - Prague, Czech Republic - 28.08.2013
experiment 2comparison with state-of-the-art
HOME
FRIENDS
WEEKEND
THEATHER
NONRELEASE
WEEKDAY
GBFRIEND
THEAT-WEEK
THEAT-FRIENDS
37 45,25 53,5 61,75 70
comparison with Adomavicius’ approach based on CFC. Musto, G. Semeraro, P. Lops, M. de Gemmis. - Contextual eVSM: a context-aware content-based recommendation framework based on distributional semantics - EC WEB 2013 - Prague, Czech Republic - 28.08.2013
experiment 2comparison with state-of-the-art
HOME
FRIENDS
WEEKEND
THEATHER
NONRELEASE
WEEKDAY
GBFRIEND
THEAT-WEEK
THEAT-FRIENDS
37 45,25 53,5 61,75 70
eVSM outperforms CF in 6 segments out of 9
C. Musto, G. Semeraro, P. Lops, M. de Gemmis. - Contextual eVSM: a context-aware content-based recommendation framework based on distributional semantics - EC WEB 2013 - Prague, Czech Republic - 28.08.2013
experiment 2 - outcomecontextual eVSM improves the predictive accuracy
of state-of-the-art approaches based on CF
C. Musto, G. Semeraro, P. Lops, M. de Gemmis. - Contextual eVSM: a context-aware content-based recommendation framework based on distributional semantics - EC WEB 2013 - Prague, Czech Republic - 28.08.2013
recap.
C. Musto, G. Semeraro, P. Lops, M. de Gemmis. - Contextual eVSM: a context-aware content-based recommendation framework based on distributional semantics - EC WEB 2013 - Prague, Czech Republic - 28.08.2013
recap• context-aware eVSM
• baseline: eVSM
• content-based recommendation framework
• distributional semantics + quantum negation
• evolution: contextual eVSM
• comparison of two approaches for context-aware eVSM
• exact pre-filtering and weighted post-filtering
• large experimental evaluation, comparison with state of the art approaches
C. Musto, G. Semeraro, P. Lops, M. de Gemmis. - Contextual eVSM: a context-aware content-based recommendation framework based on distributional semantics - EC WEB 2013 - Prague, Czech Republic - 28.08.2013C. Musto, G. Semeraro, P. Lops, M. de Gemmis. - Contextual eVSM: a context-aware content-based recommendation framework based on distributional semantics - EC WEB 2013 - Prague, Czech Republic - 28.08.2013
C. Musto, G. Semeraro, P. Lops, M. de Gemmis. - Contextual eVSM: a context-aware content-based recommendation framework based on distributional semantics - EC WEB 2013 - Prague, Czech Republic - 28.08.2013
future research.C. Musto, G. Semeraro, P. Lops, M. de Gemmis. - Contextual eVSM: a context-aware content-based recommendation framework based on distributional semantics - EC WEB 2013 - Prague, Czech Republic - 28.08.2013
evaluation with different datasets
C. Musto, G. Semeraro, P. Lops, M. de Gemmis. - Contextual eVSM: a context-aware content-based recommendation framework based on distributional semantics - EC WEB 2013 - Prague, Czech Republic - 28.08.2013
open knowledge sources and linked data for CBRS.
C. Musto, G. Semeraro, P. Lops, M. de Gemmis. - Contextual eVSM: a context-aware content-based recommendation framework based on distributional semantics - EC WEB 2013 - Prague, Czech Republic - 28.08.2013
evaluation with user-based metrics(serendipity, novelty, unexpectedness)
C. Musto, G. Semeraro, P. Lops, M. de Gemmis. - Contextual eVSM: a context-aware content-based recommendation framework based on distributional semantics - EC WEB 2013 - Prague, Czech Republic - 28.08.2013
questions?Cataldo Musto, Ph.D
[email protected]. Musto, G. Semeraro, P. Lops, M. de Gemmis. - Contextual eVSM: a context-aware content-based recommendation framework based on distributional semantics - EC WEB 2013 - Prague, Czech Republic - 28.08.2013