1. Building and Analyzing Social Networks Web Data and Semantics in Social Network Applications Dr. Bhavani Thuraisingham February 15, 2013

2. 23-2 5/17/2015 22:05 Outline 0 Reference: P. Mika, Semantic Web and Social Networks, Springer, 2008: Chapter 3, 4, 5, 6 0 Electronic Sources for Network Analysis 0 Knowledge Representation on the Semantic Web 0 Modeling and Aggregating Social Network Data 0 Developing Social Semantic Applications

3. 23-3 5/17/2015 22:05 Electronic Sources for Network Analysis 0 Electronic Discussion Networks 0 Blogs and Online Communications 0 Web-based Networks

4. 23-4 5/17/2015 22:05 Electronic Discussion Networks 0 Communication among employees using email archive 0 Email networks - E.g., Enron email network analysis 0 Build network from the email communications 0 Public forums and email lists 0 Group communication

5. 23-5 5/17/2015 22:05 Blogs and Online Communications 0 Content analysis of blogs (web logs) 0 Trend analysis of blogs 0 Online social networks - Facebook, Twitter, LinkedIn, Foursquare 0 Sentiment analysis

6. 23-6 5/17/2015 22:05 Web-based Networks 0 Web pages from a network 0 Contents of web pages 0 Mine and analyze the web pages 0 Web Mining - Web content mining - Web structure mining - Web log mining (who visited the web pages)

7. 23-7 5/17/2015 22:05 Knowledge Representation on the Semantic Web 0 Ontologies and their role in the semantic web 0 Ontology languages for the semantic web

8. 23-8 5/17/2015 22:05 Ontologies and Their Role in the Semantic Web 0 Ontologies are expressed in formal languages with well- defined semantics 0 Ontologies build upon a shared understanding with a community 0 RDF and OWL are languages for the semantic web 0 More expressive languages have less reasoning power

9. 23-9 5/17/2015 22:05 Ontology Languages for the Semantic Web 0 RDF 0 RDF Schema 0 RDF Vocabulary 0 RDF and FOAF 0 RDF and Semantics 0 SPARQL (query language for RDF) 0 OWL – Web Ontology Language 0 Comparison to UML and the ER Model

10. 23-10 5/17/2015 22:05 Modeling and Aggregating Social Network Data 0 Network Data Representation 0 Ontological Representation of Social Individuals 0 Ontological Relationship of Social Relationships 0 Aggregating and Reasoning with Social Network Data

11. 23-11 5/17/2015 22:05 Network Data Representation 0 Graphs 0 Matrices 0 Number the nodes and use the numbers to represent the edges (e.g., 12 means edge between nodes 1 and 2) 0 GraphML (XML for graphs) 0 Do not support the aggregation of network data 0 Key challenges: Identification and Disambiguation

12. 23-12 5/17/2015 22:05 Ontological Representation of Social Individuals 0 FOAF is an example of an ontological representation of individuals 0 Eliminates the drawbacks of early social networks like Friendster, Orkut 0 The early social networks had centralized control and were difficult to manage 0 FOAF is distributed and has a rich ontology to characterize individuals

13. 23-13 5/17/2015 22:05 Ontological Representation of Social Relationships 0 Social networks such as FOAF need to be extended to support relationships 0 Support the integration of social information 0 Integrates/aggregates multiple social networks 0 Properties of relationships - Sign: Positive or Negative relationships - Strength (e.g., frequency of contact) - Provenance (different ways of viewing relationships) - Relationship History - Relationship roles 0 Conceptual models for social data – semantic net, RDF

14. 23-14 5/17/2015 22:05 Aggregating and Reasoning with Social Network Data 0 Representing Identity - URI (Universal Resource Identifier) - Disambiguation (A and B are the same; There are two people called John Smith) - OWL has the “sameAS” property 0 Equality 0 The property sameAs is reflexive, symmetric and transitive 0 Descriptive Logic vs. Rule based reasoners - Rule based reasoners use forward chaining and backward chaining - Descriptive logic is used for classification and checking for ontology consistency

15. 23-15 5/17/2015 22:05 Developing Social Semantic Applications 0 Building Semantic Web Applications with Social Network Features 0 Flink: The Social Network of the Semantic Web Community 0 Openacademia: Distributed semantic web-based publication management

16. 23-16 5/17/2015 22:05 Building Semantic Web Applications with Social Network Data 0 General Architecture - Sesame for storage and reasoning (alternative is Jena) = Sesame manages the data sources - Sesame Client API - Querying through SPARQL - Elmo and associated tools for building ontologies and interfacing to RDF data 0 Social Network Applications (e.g., FLINK) are built on top of the architecture as applications

17. 23-17 5/17/2015 22:05 Flink: The Social Network of the Semantic Web Community 0 Flink was developed by Peter Mika; it is a semantic web representation of any online social data 0 Current instantiation uses semantic web researchers are nodes and their collaboration as links 0 Visualization tools for visualizing the nodes and links 0 Flink social networks are decomposed and stored as RDF triples and managed by Sesame

18. 23-18 5/17/2015 22:05 Openacademia: Distributed Semantic Web-based Publication Management 0 Openacademia is a social network application for maintaining scientific publications 0 Data from multiple data stores (e.g., FOAF profiles, publications) and access via Elmo crawler 0 Data converted into RDF and managed by Sesame 0 Openacademia servlet queries Sesame (SPARQL queries) and aggregates the data and presents to the user