Laurent Perrussel and Jean-Marc Thévenin
This paper focuses on the features of belief change in a multi-agent context where agents consider beliefs and disbeliefs. Agents receive messages holding information from other agents and change their belief state accordingly. Agents may refuse to adopt incoming information if it is considered as not reliable. For this, agents maintain a preference relation over other agents embedded in the multi-agent system, in order to decide if they accept or reject the incoming information whenever inconsistencies occur. This process leads to non-prioritized belief revision. We focus here on this latter stage when agents refuse to change their (dis)beliefs and thus prefer to stay in opposite (dis)beliefs. In this case they inform their sources of information whether they actually changed their beliefs. We describe a process of justification where an agent states their preferences to the sender of the rejected information. This stage may lead the sender to also reconsider its own belief state.