The present article introduces a five-valued logic and a deductive system. Here, the logic presented is a relevant fragment of the @-logic, which is also a space-time logic. These five values correspond to the following semantics: unknown, possibly known but…

In this article we will introduce certain considerations that must be taken into account while implementing the change operations of the belief change theory. The abstract models of bellief change make no considerations in respecto to the internal structures of…