Local Models Semantics, or contextual reasoning equals locality plus compatibility

In this paper we present a new semantics, called Local Models Semantics, an d use it to provide a foundation to reasoning with contexts. This semantics captures and makes precise the two main intuitions underlying contextual r easoning: (i) reasoning is mainly local and uses only part of what is poten tially available Ie,g., what is known, the available inference procedures), this part is what we call context (of reasoning); however (ii) there is co mpatibility among the reasoning performed in different contexts. We validat e our semantics by formalizing two important forms of contextual reasoning: reasoning with viewpoints and reasoning about belief. (C) 2001 Elsevier Sc ience B,V. All rights reserved.