Large online communities that contribute and share content account nowadays for a significant and highly qualitative portion of the data on the Web. Examples of collaborative applications oriented towards building repositories of quality user-generated content include online encyclopedias (Wikipedia, Knol), photo sharing sites (Flickr) or rating sites (Epinions). An important trend in such platforms aims at exploiting user relationships, links between users (e.g., social links), in order to improve core functionalities in the system. For instance, search, recommendation or access control can benefit from socially-driven approaches.

This is especially the case when links can be viewed as being signed, indicating a positive or negative attitude; possible meanings for positive links could be trust, friendship or similarity, while for negative links they could stand for distrust, opposition or antagonism. In settings where explicit relationships do not exist, are sparse or are inadequate indicators of one's attitude towards fellow members of the community, it becomes thus important to uncover implicit user inter-connections, positive or negative links, from relevant user activities and their interactions.

Our work thus far shows encouraging results. From a collection of Wikipedia articles and their revision history, we have investigated mechanisms by which relationships between Wikipedia contributors - in the form of signed directed links - can be inferred based their interactions. Our study sheds light into principles underlying a signed network that is captured by social interaction. We have looked into whether this network over Wikipedia contributors represents indeed a plausible configuration of link signs, by assessing connections to social theories such as structural balance and status, which have already been considered in online communities. We have thus obtained strong evidence that the Wikipedia network of contributors does reveal an implicit signed configuration and that it has similar characteristics to the explicit ones.

• Designing methods to automatically extract signed networks from the social Web,
• Establishing sound metrics and methods for validating the inferred signed networks,
• Addressing the computational challenges inherent to the large-scale extraction and creation of the networks,
• Designing applications (e.g., recommandation systems, personalised search) that fully exploit the signed social links.

1. Silviu Maniu, Bogdan Cautis and Talel Abdessalem. Building a Signed Network from Interactions in Wikipedia. In First ACM SIGMOD Workshop on Databases and Social Networks (DBSocial), 2011. [pdf]
2. Silviu Maniu, Talel Abdessalem and Bogdan Cautis. Casting a web of trust over Wikipedia: an interaction-based approach. In Proceedings of the 20th International Conference Companion on World wide web (WWW), 2011. Poster paper. [pdf]