Talk on Mining Locality-Preserving Trust Hierarchies in Signed Networks

[Roopa Gurav]

Talk on
“Mining Locality-Preserving Trust Hierarchies in Signed Networks”
By
Ms. Mili Ann Abraham
2nd year M.Tech Student
International School of Information Management
University of Mysore, Mysore

Date and Time: 12 PM, Saturday, June 30, 2012

You are cordially invited
Dr.Shalini R Urs
Executive Director and Professor
International School of Information Management
University of Mysore, Mysore



Abstract
The phenomena of social hierarchy and stratification among humans could be traced back to theorigin of human society. Presently, the growing popularity of online social networks hasprovided with an opportunity to analyze these well-studied phenomena over different networks atdifferent scales. Generally, a social network can be considered as a collection of actors and theirinteractions (connections). In signed networks, there is an explicit show of trust (positive) ordistrust (negative) among the actors. That is, an actor can designate others as friends or foes.Examples of signed networks include the Slashdot Zoo network, Epinions etc. In a socialnetwork, actors tend to connect with each other on the basis of their perceived social hierarchy.

The concept of social hierarchy can be stated as the emergence of a tree-like structurecomprising of actors in a top-down fashion in the order of their ranks, describing a specificparent-child relationship, viz. child trusts parent. However, owing to the presence of positive aswell as negative interactions in signed networks, deriving trust hierarchies is a non-trivialchallenge. We argue that traditional notions are insufficient to derive hierarchies underlyingsigned networks.

To build hierarchies in signed networks, we introduce two interpretations of trust/goodnessnamely ‘presence of trust (good)’ and ‘lack of distrust (not bad)’. In order to develop a hierarchysignifying both trust and distrust more effectively, the above interpretations are combined andthe actors are arranged according to their aggregate deserve (trust) values. We then introduce ahypothesis for building hierarchies based on deserve values while preserving the locality ofinteractions between actors. In this sense, even though a hierarchy represents an aggregate socialstructure, the relationships are formed from local structures. The hierarchies obtained using ourhypothesis are said to be locality-preserving, with each hierarchy representing a well-definedlocal community. Each such hierarchy contains a community representative at the root. Modelingsuch locality-preserving hierarchies in trust networks finds applications in community detection,information dissemination and locality-based governance for the population.


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