Abstract
Belief change and non-monotonic reasoning are
usually viewed as two sides of the same coin,
with results showing that one can formally be de-
fined in terms of the other. In this paper we
show that we can also integrate the two formalisms
by studying belief change within a (preferential)
non-monotonic framework. This integration relies
heavily on the identification of the monotonic core
of a non-monotonic framework. We consider belief
change operators in a non-monotonic propositional
setting with a view towards preserving consistency.
These results can also be applied to the preservation of coherence—an important notion within
the field of logic-based ontologies. We show that
the standard AGM approach to belief change can
be adapted to a preferential non-monotonic framework, with the definition of expansion, contraction,
and revision operators, and corresponding representation results. Surprisingly, preferential AGM
belief change, as defined here, can be obtained in
terms of classical AGM belief change