Many people today participate in more than one social network on a daily basis; such networks can be seen as dynamic environments containing knowledge about their members. From a KR perspective, these environments are complex in many dimensions; for instance, it is not clear how to treat news being communicated through the network, especially when it contradicts a user’s own knowledge, or when ...

Many real incidents demonstrate that users of Online Social Networks need mechanisms that help them manage their interactions by increasing the awareness of the different contexts that coexist in Online Social Networks and preventing them from exchanging inappropriate information in those contexts or disseminating sensitive information from some contexts to others. Contextual integrity is a pri...

Stream query processing is becoming increasingly important as more time-oriented data is produced and analyzed nowadays. Examples for stream-based applications include sensor networks and infrastructure monitoring, electronic trading on Wall Street, or social networks. In the last decade several technologies have emerged to address the challenges of processing such high-volume and realtime data...

As more business-to-business organizations consider using social media to attract customers, the acceptance of social media technology among employees becomes crucial. We assume particular factors to matter for organizational users as compared to private users. Study 1 which is based on 46 in-depth interviews explores six system design features that are critical for social media usage among org...

In this paper we present an abductive framework for handling requests for updating a deductive database. Updates are tackled in a consistency-preserving manner so that it is guaranteed that the database state resulting of applying the update is consistent; that is, it satisfies the set of its integrity constraints. Moreover, if view updates are requested, they are appropriately translated into ...