Multi-Context Systems with Activation Rules Stefan Mandl and Bernd Ludwig Dept. of Computer Science 8 (Artificial Intelligence), Friedrich-Alexander-Universit¨ at Erlangen-N¨ urnberg, Haberstraße 2, D-91058 Erlangen, Germany WWW home page: http://www8.informatik.uni-erlangen.de {Stefan.Mandl, Bernd.Ludwig}@cs.fau.de Abstract. Multi-Context Systems provide a formal basis for the inte- gration of knowledge from different knowledge sources. Yet, it is easy to conceive of applications where not all knowledge sources may be used together all the time. We present a natural extension of Multi-Context Systems by adding the notion of activation rules that allows modeling the applicability or relevance of contexts depending on beliefs in the var- ious contexts and their mutual dependencies. We give a short account on possible consequence relations for Multi-Context System with Activation Rules and discuss a potential application in information retrieval. 1 Introduction Figure 1 shows the by now almost classical motivating example for formal Multi- Context Systems (MCS). Mr.1 and Mr.2 have different perspectives on the same real world object. There are queries that either Mr.1 or Mr.2 cannot answer by Fig. 1. Magic box (taken from [5]) himself, depending on the configuration of the scenario. MCS provide a basis for formal representation of such settings by using the key concept of bridge rules that can be used to describe information flow between the involved parties. For instance, the bridge rule Mr.1:left ∨ Mr.1:right ← Mr.2:left. would transfer enough of Mr.2’s knowledge to Mr.1 to enable him to come up with the correct conclusion that from his point of view the ball must be hidden behind the left plate of the magic box.