an initial homophily indicator to reinforce context-aware semantic computing
TRANSCRIPT
An Initial Homophily Indicator to Reinforce Context-Aware Semantic
ComputingA. Rivero-Rodriguez, P. Pileggi, O. Nykänen
Tampere University of TechnologyTampere, Finland
June 3, 2015Riga, LatviaCICSyN 2015: Computational Intelligence, Communication Systems and Networks
This talk describes the benefits of using social network analysis, in particular homophily, in context-aware systems
Context SNA/Homophily Indicators
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What is context?
Context is any information that can be used to characterize the situation of an entity, where an entity can be a person, places, or physical or computational object1.
Context is the sum total of what is known about an individual along with what he or she is currently experiencing.
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Context
Context-aware system can be found everywhere, even in your phone…
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Context
Social Network Analysis
Social Network Analysis (SNA) focuses on the discovery and evolution of relations among entities (people, organizations, activities, etc.) [21].
We want to use SNA techniques to understand existing systems. It can be used for modelling for link prediction etc.
SNA is not solely useful for understanding a system, but for others tasks such as Prediction, Recommendation, etc. For example, Amazon’s recommender system.
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SNA
Homophily states that connections between similar people happens at a higher rate than among dissimilar people
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Network that exhibits homophily
Homophily is ubiquitous in social systems.
Network of romantic relationships in a highschool exhibits:inverse homophily according to genderdirect homophily according to age
Two mechanisms underlying homophilySelectionSocial influence (socialization)
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Measuring Homophily in social network
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n number of present edges in G.p number of possible edges in G.Proportion of edges in the network
Proportion of homophily edges.
Proportion of heterophily edges.
Comparison of homophily indicators
Existing affinity indicator Our homophily indicator
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+1
-1
0
Homophily
Heterophily+1
∞
0Heterophily
Homophily
Difficult to interpret and utilizeWhat is aff value for a system with only homophilic connections?
Easier to interpret.Homophily and heterophily are equally important.
Experimenting with hom indicators. Description of the nodobo dataset
Smartphone social interaction data27 senior high-school studentsData collected for 5 months: Sep’10 – Feb’11 (only considered 105 days with data)We used the bluetooth data and build a graph G
• Each user is a node in G• There is a link between two users if they have been in
proximity for more than 60 min a day. (preanalysos)
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Experiment settings
Homophily conditions: Two users are expected to be connected if they have more than f friends in common
We have discretize the 105 days of data into W periods of lenght L, so that
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Experiment settings
Homophily conditions: Two users are expected to be connected if they have more than f friends in common
We have discretize the 105 days of data into W periods of lenght L, so that
Several experiments, such as:• Experiment A: W=15, f=2• Experiment B: W=5, f=3
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System parameters
Results & Observations13
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Figure 2. Aff and Hom indicator values reported for Experiment A.
Figure 3. Aff and Hom indicator values reported for Experiment B.
Conclusions & Future Work
We propose an homophily indicator that overcomes the weaknesses of others proposed in the literature. It is easier to understand and interpret, potentially useful in existing context-aware systems.
Future work includes• the extension of the indicator to account for time periods, • the development of model driven solutions based for
context inference based on our Hom indicator.
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Alejandro [email protected]