Monotonicity and Persistence in Preferential Logics

An important characteristic of many logics for Arti cial Intelligence is their nonmonotonicity. This means that adding a formula to the premises can invalidate some of the consequences. There may, however, exist formulae that can always be safely added to the premises without destroying any of the consequences: we say they respect monotonicity. Also, there may be formulae that, when they are a consequence, can not be invalidated when adding any formula to the premises: we call them conservative. We study these two classes of formulae for preferential logics, and show that they are closely linked to the formulae whose truth-value is preserved along the preferential ordering. We will consider some preferential logics for illustration, and prove syntactic characterization results for them. The results in this paper may improve the e ciency of theorem provers for preferential logics.

• Type: Journal
• Year: 1998
• Where: CORR
• Authors: Joeri Engelfriet
• Keywords: Arti Cial Intelligence, CORR 1998, Education, Formulae, Preferential Logics