social recommendationking/pub/bayareasearchmeetup2012.pdfsocial recommendation, irwin king @ bay...
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Social Recommendation, Irwin King @ Bay Area Search Group Meetup, February 22, 2012
Social Recommendation
Irwin King with Hao Ma
ATT Labs Research&
Department of Computer Science and EngineeringThe Chinese University of Hong Kong
[email protected]://www.cse.cuhk.edu.hk/~king
©2012 Irwin King. All rights reserved.
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Social Recommendation, Irwin King @ Bay Area Search Group Meetup, February 22, 2012
Information and more Information!
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Social Recommendation, Irwin King @ Bay Area Search Group Meetup, February 22, 2012
ConsumerSatisfaction
CompanyProfit
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Social Recommendation, Irwin King @ Bay Area Search Group Meetup, February 22, 2012
Real Life Examples
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Social Recommendation, Irwin King @ Bay Area Search Group Meetup, February 22, 2012
Real Life Examples
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Social Recommendation, Irwin King @ Bay Area Search Group Meetup, February 22, 2012
Real Life Examples
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Social Recommendation, Irwin King @ Bay Area Search Group Meetup, February 22, 2012
• Introduction
• Basic Techniques
• Collaborative filtering
• Matrix factorization
• Different Models
• Social graph
• Social ensemble
• Social distrust
• Website recommendation
On The Menu
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Social Recommendation, Irwin King @ Bay Area Search Group Meetup, February 22, 2012
Basic Approaches• Content-based Filtering
• Recommend items based on key-words
• More appropriate for information retrieval
• Collaborative Filtering (CF)
• Look at users with similar rating styles
• Look at similar items for each item
Underling assumption: personal tastes are correlated-- Active users will prefer those items which the similar
users prefer!
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Social Recommendation, Irwin King @ Bay Area Search Group Meetup, February 22, 2012
FrameworkItems
Users
• The tasks
• Find the unknown rating!
• Which item(s) should be recommended?
i1 i2 ij imu1
u2 1 3 4 2 5 3 4
ui 3 4 rij 3 4 3 4 4
un 1 3 5 2 4 1 3
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Social Recommendation, Irwin King @ Bay Area Search Group Meetup, February 22, 2012
User-User Similarity
5
43
32
?
Q1: How to measure the similarity?
Q2: How to select neighbors?
target
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Social Recommendation, Irwin King @ Bay Area Search Group Meetup, February 22, 2012
User-based Collaborative FilteringItems
Users
u1
u2 1 3 4 2 5 3 4
u3
u4 3 4 3 4 3 4 4
u5
u6 1 3 5 2 4 1 3
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Social Recommendation, Irwin King @ Bay Area Search Group Meetup, February 22, 2012
User-based Collaborative FilteringItems
Users
u1
u2 1 3 4 2 5 3 4
u3
u4 3 4 3 4 3 4 4
u5
u6 1 3 5 2 4 1 3
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Social Recommendation, Irwin King @ Bay Area Search Group Meetup, February 22, 2012
User-based Collaborative FilteringItems
Users
u1
u2 1 3 4 2 5 3 4
u3
u4 3 4 3 4 3 4 4
u5
u6 1 3 5 2 4 1 3
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Social Recommendation, Irwin King @ Bay Area Search Group Meetup, February 22, 2012
User-based Collaborative FilteringItems
Users
u1
u2 1 3 4 2 5 3 4
u3
u4 3 4 3 4 3 4 4
u5
u6 1 3 5 2 4 1 3
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Social Recommendation, Irwin King @ Bay Area Search Group Meetup, February 22, 2012
User-based Collaborative FilteringItems
Users
u1
u2 1 3 4 2 5 3 4
u3
u4 3 4 3 4 3 4 4
u5
u6 1 3 5 2 4 1 3
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Social Recommendation, Irwin King @ Bay Area Search Group Meetup, February 22, 2012
User-based Collaborative Filtering• Predict the ratings of active users based on the ratings
of similar users found in the user-item matrix
• Pearson correlation coefficient
• Cosine measure
w(a, i) =�
j(raj � r̄a)(rij � r̄i)⇥�j(raj � r̄a)2
�j(rij � r̄i)2
j � I(a) ⇥ I(i)
c(a, i) =ra · ri
||ra||2 ⇥ ||ri||2ui 1 3 4 2 5 3 4
ua 3 4 3 4 3 4 4
1 3 5 2 4 1 3
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Social Recommendation, Irwin King @ Bay Area Search Group Meetup, February 22, 2012
Nearest Neighbor Approaches
• Identify highly similar users to the active one
• All with a measure greater than a threshold
• Best K ones
• Prediction raj = r̄a +�
i w(a, i)(rij � r̄i)�i w(a, i)
[Sarwar, 00a]
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Social Recommendation, Irwin King @ Bay Area Search Group Meetup, February 22, 2012
Collaborative Filtering
• Memory-based Method (Simple)
• User-based Method [Xue et al., SIGIR ’05]
• Item-based [Deshpande et al., TOIS ’04]
• Model-based (Robust)
• Clustering Methods [Hkors et al, CIMCA ’99]
• Bayesian Methods [Chien et al., IWAIS ’99]
• Aspect Method [Hofmann, SIFIR ’03]
• Matrix Factorization [Sarwar et al., WWW ’01]
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Social Recommendation, Irwin King @ Bay Area Search Group Meetup, February 22, 2012
Collaborative Filtering
• Memory-based (Neighborhood-based)
• User-based
• Item-based
• Model-based
• Clustering Methods
• Bayesian Methods
• Matrix Factorization
• etc.
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Social Recommendation, Irwin King @ Bay Area Search Group Meetup, February 22, 2012
Collaborative Filtering
• Memory-based (Neighborhood-based)
• User-based
• Item-based
• Model-based
• Clustering Methods
• Bayesian Methods
• Matrix Factorization
• etc...
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Social Recommendation, Irwin King @ Bay Area Search Group Meetup, February 22, 2012
Matrix Factorization
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Social Recommendation, Irwin King @ Bay Area Search Group Meetup, February 22, 2012
Matrix Factorization
• Matrix Factorization in Collaborative Filtering
• To fit the product of two (low rank) matrices to the observed rating matrix
• To find two latent user and item feature matrices
• To use the fitted matrix to predict the unobserved ratings
Instruction
! Definition of MF in CF:" To fit the product of two (low rank) matrices to the observed
rating matrix.
" To find two latent user and item feature matrices.
" To use the fitted matrix to predict the unobserved ratings.
11 1 11 1
1 1
k n
m mk k kn
u u v v
Y UV
u u v v
! "! "# $# $
% & # $# $# $# $' (' (
! !
" # " " # "
$ $
Item-specific latent
feature column vectorUser-specific latent
feature vector
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Social Recommendation, Irwin King @ Bay Area Search Group Meetup, February 22, 2012
Matrix Factorization
• Optimization Problem
• Given a m x n rating matrix R, to find two matrices and ,
where , is the number of factors
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Social Recommendation, Irwin King @ Bay Area Search Group Meetup, February 22, 2012
Matrix Factorization
• Models
• SVD-like Algorithm
• Regularized Matrix Factorization (RMF)
• Probabilistic Matrix Factorization (PMF)
• Non-negative Matrix Factorization (NMF)
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Social Recommendation, Irwin King @ Bay Area Search Group Meetup, February 22, 2012
SVD-like Algorithm
• Minimizing
• For collaborative filtering
where is the indicator function that is equal to 1 if user ui rated item vj and equal to 0 otherwise.
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Social Recommendation, Irwin King @ Bay Area Search Group Meetup, February 22, 2012
Regularized Matrix Factorization• Minimize the loss based on the observed ratings with
regularization terms to avoid over-fitting problem
where .
• The problem can be solved by simple gradient descent algorithm.
Regularization terms
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Social Recommendation, Irwin King @ Bay Area Search Group Meetup, February 22, 2012
Social Recommendation Using Probabilistic Matrix Factorization
[Ma et al., CIKM2008]
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Social Recommendation, Irwin King @ Bay Area Search Group Meetup, February 22, 2012
Challenges•Data sparsity problem
My Blueberry Nights (2008)
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Social Recommendation, Irwin King @ Bay Area Search Group Meetup, February 22, 2012
ChallengesMy Movie Ratings
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Social Recommendation, Irwin King @ Bay Area Search Group Meetup, February 22, 2012
Challenges•Traditional recommender systems ignore the social
connections between users
Which one should I
choose?
Recommendations from friends
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Social Recommendation, Irwin King @ Bay Area Search Group Meetup, February 22, 2012
Social Trust Graph User-Item Rating Matrix
Problem Definition
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Social Recommendation, Irwin King @ Bay Area Search Group Meetup, February 22, 2012
R. Salakhutdinov and A. Mnih (NIPS’08)
User-Item Matrix Factorization
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Social Recommendation, Irwin King @ Bay Area Search Group Meetup, February 22, 2012
SoRec
SoRec
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Social Recommendation, Irwin King @ Bay Area Search Group Meetup, February 22, 2012
SoRec
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Social Recommendation, Irwin King @ Bay Area Search Group Meetup, February 22, 2012
SoRec
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Social Recommendation, Irwin King @ Bay Area Search Group Meetup, February 22, 2012
• Lack of interpretability
• Does not reflect the real-world recommendation process
SoRec
Disadvantages of SoRec
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Social Recommendation, Irwin King @ Bay Area Search Group Meetup, February 22, 2012
Learning to Recommend with Social Trust Ensemble
[Ma et al., SIGIR2009]
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Social Recommendation, Irwin King @ Bay Area Search Group Meetup, February 22, 2012
1st Motivation
•Users have their own characteristics, and they have different tastes on different items, such as movies, books, music, articles, food, etc.
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Social Recommendation, Irwin King @ Bay Area Search Group Meetup, February 22, 2012
2nd Motivation
•Users can be easily influenced by the friends they trust, and prefer their friends’ recommendations.
Where to have dinner? Ask
Ask
Ask
Good
Very Good
Cheap & Delicious
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Social Recommendation, Irwin King @ Bay Area Search Group Meetup, February 22, 2012
•Users have their own characteristics, and they have different tastes on different items, such as movies, books, music, articles, food, etc.
•Users can be easily influenced by the friends they trust, and prefer their friends’ recommendations.
•One user’s final decision is the balance between his/her own taste and his/her trusted friends’ favors.
Motivations
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Social Recommendation, Irwin King @ Bay Area Search Group Meetup, February 22, 2012
[R. Salakhutdinov, et al., NIPS2008]
User-Item Matrix Factorization
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Social Recommendation, Irwin King @ Bay Area Search Group Meetup, February 22, 2012
Recommendations by Trusted Friends
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Social Recommendation, Irwin King @ Bay Area Search Group Meetup, February 22, 2012
Recommendation with Social Trust Ensemble
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Social Recommendation, Irwin King @ Bay Area Search Group Meetup, February 22, 2012
Recommendation with Social Trust Ensemble
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Social Recommendation, Irwin King @ Bay Area Search Group Meetup, February 22, 2012
Recommend with Social Distrust[Ma et al., RecSys2009]
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Social Recommendation, Irwin King @ Bay Area Search Group Meetup, February 22, 2012
Trust vs. Social• Trust-aware
• Trust network: unilateral relations
• Trust relations can be treated as “similar” relations
• Few datasets available on the Web
• Social-based
• Social friend network: mutual relations
• Friends are very diverse, and may have different tastes
• Lots of Web sites have social network implementation
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Social Recommendation, Irwin King @ Bay Area Search Group Meetup, February 22, 2012
•Users’ distrust relations can be interpreted as the “dissimilar” relations
•On the web, user Ui distrusts user Ud indicates that user Ui disagrees with most of the opinions issued by user Ud.
•What to do if a user distrusts many people?
•What to do if many people distrust a user?
Distrust
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Social Recommendation, Irwin King @ Bay Area Search Group Meetup, February 22, 2012
Distrust
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Social Recommendation, Irwin King @ Bay Area Search Group Meetup, February 22, 2012
•Users’ trust relations can be interpreted as the “similar” relations
•On the web, user Ui trusts user Ut indicates that user Ui agrees with most of the opinions issued by user Ut.
Trust
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Social Recommendation, Irwin King @ Bay Area Search Group Meetup, February 22, 2012
Trust
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Social Recommendation, Irwin King @ Bay Area Search Group Meetup, February 22, 2012
Web Site Recommendation[Ma et al., SIGIR 2011]
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Social Recommendation, Irwin King @ Bay Area Search Group Meetup, February 22, 2012
Traditional Search Paradigm
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Social Recommendation, Irwin King @ Bay Area Search Group Meetup, February 22, 2012
“Search” to “Discovery”
News%Corp.%
Windows%8% iPhone%5%
How%to%cook?%
News%Corp.%
Windows%8% iPhone%5%
How%to%cook?%
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Social Recommendation, Irwin King @ Bay Area Search Group Meetup, February 22, 2012
Challenges in Web Site Recommendation
• Infeasible to ask Web users to explicitly rate Web site
• Not all the traditional methods can be directly applied to the Web site recommendation task
• Can only take advantages of implicit user behavior data
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Social Recommendation, Irwin King @ Bay Area Search Group Meetup, February 22, 2012
Motivations
• A Web user’s preference can be represented by how frequently a user visits each site
• Higher visiting frequency on a site means heavy information needs while lower frequency indicates less interests
• User-query issuing frequency data can be used to refine a user’s preference
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Social Recommendation, Irwin King @ Bay Area Search Group Meetup, February 22, 2012
Using Clicks as Ratings
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Social Recommendation, Irwin King @ Bay Area Search Group Meetup, February 22, 2012
Probabilistic Factor Model
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Social Recommendation, Irwin King @ Bay Area Search Group Meetup, February 22, 2012
Probabilistic Factor Model
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Social Recommendation, Irwin King @ Bay Area Search Group Meetup, February 22, 2012
Collective Probabilistic Factor Model
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Social Recommendation, Irwin King @ Bay Area Search Group Meetup, February 22, 2012
Dataset• Anonymous logs of Web sites visited by users who
opted-in to provide data through browser toolbar
• URLs of all the Web sites are truncated to the site level
• After pruning one month data, we have 165,403 users, 265,367 URLs and 442,598 queries
• User-site frequency matrix has 2,612,016 entries, while in user-query frequency matrix has 833,581 entries
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Social Recommendation, Irwin King @ Bay Area Search Group Meetup, February 22, 2012
Performance Comparison
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Social Recommendation, Irwin King @ Bay Area Search Group Meetup, February 22, 2012
Impact of Parameters
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Social Recommendation, Irwin King @ Bay Area Search Group Meetup, February 22, 2012
Impact of Parameters
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Social Recommendation, Irwin King @ Bay Area Search Group Meetup, February 22, 2012
Concluding Remarks
• Social recommendation extends traditional models and techniques by using social graphs, ensembles, distrust relationships, clicks, etc.
• Fusing of social behavior information, e.g., social relationships, personal preferences, media consumption patters, temporal dynamics, location information, etc. provides better models for social recommendations
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Social Recommendation, Irwin King @ Bay Area Search Group Meetup, February 22, 2012
Acknowledgments• Ritesh Agrawal
• David Grangier
• Jean-Francois Paiement
• Remi Zajac
• Shouyuan Chen (Ph.D.)
• Baichuan Li (Ph.D.)
• Zhenjiang Lin (Ph.D.)
• Guang Ling (Ph.D.)
• Hao Ma (Microsoft)
• Haiqin Yang (Postdoc)
• Connie Yuen (Ph.D.)
• Xin Xin (Postdoc)
• Chao Zhou (Ph.D.)
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Social Recommendation, Irwin King @ Bay Area Search Group Meetup, February 22, 2012
On-Going ResearchMachine Learning
• Smooth Optimization for Effective Multiple Kernel Learning (AAAI’10)
• Simple and Efficient Multiple Kernel Learning By Group Lasso (ICML’10)
• Online Learning for Group Lasso (ICML’10)
• Heavy-Tailed Symmetric Stochastic Neighbor Embedding (NIPS’09)
• Adaptive Regularization for Transductive Support Vector Machine (NIPS’09)
• Direct Zero-norm Optimization for Feature Selection (ICDM’08)
• Semi-supervised Learning from General Unlabeled Data (ICDM’08)
• Learning with Consistency between Inductive Functions and Kernels (NIPS’08)
• An Extended Level Method for Efficient Multiple Kernel Learning (NIPS’08)
• Semi-supervised Text Categorization by Active Search (CIKM’08)
• Transductive Support Vector Machine (NIPS’07)
• Global and local learning (ICML’04, JMLR’04)
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Social Recommendation, Irwin King @ Bay Area Search Group Meetup, February 22, 2012
On-Going ResearchWeb Intelligence/Information Retrieval
• Learning to Suggest Questions in Online Forums (AAAI’11)
• Diversifying Query Suggestion Results (AAAI’10)
• A Generalized Co-HITS Algorithm and Its Application to Bipartite Graphs (KDD’09)
• Entropy-biased Models for Query Representation on the Click Graph (SIGIR’09)
• Effective Latent Space Graph-based Re-ranking Model with Global Consistency (WSDM’09)
• Formal Models for Expert Finding on DBLP Bibliography Data (ICDM’08)
• Learning Latent Semantic Relations from Query Logs for Query Suggestion (CIKM’08)
• RATE: a Review of Reviewers in a Manuscript Review Process (WI’08)
• MatchSim: link-based web page similarity measurements (WI’07)
• Diffusion rank: Ranking web pages based on heat diffusion equations (SIGIR’07)
• Web text classification (WWW’07)
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Social Recommendation, Irwin King @ Bay Area Search Group Meetup, February 22, 2012
On-Going ResearchRecommender Systems/Collaborative Filtering
• Probabilistic Factor Models for Web Site Recommendation (SIGIR’11)
• Recommender Systems with Social Regularization (WSDM’11)
• UserRec: A User Recommendation Framework in Social Tagging Systems (AAAI’10)
• Learning to Recommend with Social Trust Ensemble (SIRIR’09)
• Semi-Nonnegative Matrix Factorization with Global Statistical Consistency in Collaborative Filtering (CIKM’09)
• Recommender system: accurate recommendation based on sparse matrix (SIGIR’07)
• SoRec: Social Recommendation Using Probabilistic Matrix Factorization (CIKM’08)
Human Computation
• A Survey of Human Computation Systems (SCA’09)
• Mathematical Modeling of Social Games (SIAG’09)
• An Analytical Study of Puzzle Selection Strategies for the ESP Game (WI’08)
• An Analytical Approach to Optimizing The Utility of ESP Games (WI’08)
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Social Recommendation, Irwin King @ Bay Area Search Group Meetup, February 22, 2012
Weaving Services and People on the World Wide Web
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5965002463879
springer.com
ISBN 978-3-642-00569-5
Weaving Services and People
on the World W
ide Web
Irwin KingRicardo Baeza-Yates (Eds.)
King · Baeza-Yates (Eds.)
King · Baeza-Yates (Eds.)
Weaving Services and People on the World Wide WebEver since its inception, the Web has changed the landscape of human experiences on how we interact with one another and data through service infrastructures via various computing devices. This interweaving environment is now becoming ever more embedded into devices and systems that integrate seamlessly on how we live, both in our working or leisure time.
For this volume, King and Baeza-Yates selected some pioneering and cutting-edge research work that is pointing to the future of the Web. Based on the Workshop Track of the 17th International World Wide Web Conference (WWW2008) in Beijing, they selected the top contributions and asked the authors to resubmit their work with a minimum of one third of additional material from their original workshop manuscripts to be considered for this volume. After a second-round of reviews and selection, 16 contributions were !nally accepted.
The work within this volume represents the tip of an iceberg of the many exciting advancements on the WWW. It covers topics like semantic web services, location-based and mobile applications, personalized and context-dependent user interfaces, social networks, and folksonomies. The presentations aim at researchers in academia and industry by showcasing latest research !ndings. Overall they deliver an excellent picture of the current state-of-the-art, and will also serve as the basis for ongoing research discussions and point to new directions.
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Social Recommendation, Irwin King @ Bay Area Search Group Meetup, February 22, 2012
VeriGuide• Similarity text detection system
• Developed at CUHK
• Promote and uphold academic honesty, integrity, and quality
• Support English, Traditional and Simplified Chinese
• Handle .doc, .txt, .pdf, .html, etc. file formats
• Generate detailed originality report including readability
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Social Recommendation, Irwin King @ Bay Area Search Group Meetup, February 22, 2012
Q & A
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