A recent direction within belief revision theory is to develop a theory of belief change for the Horn knowledge representation framework. We consider questions related to the complexity aspects of previous work, leading to questions about Horn envelopes (or Horn LUB’s), introduced earlier in the context of knowledge compilation. A characterization is obtained of the remainders of a Horn belief ...

This report presents a case of a 31-year-oldwoman successfully treatedmedically for a noncommunicating rudimentary horn ectopic pregnancy who presented with a second, successive rudimentary horn pregnancy. Patient underwent laparoscopic excision of right rudimentary horn and right salpingectomy after failedmethotrexate therapy. Given the potential for rupture and recurrence, serious efforts sho...

This report presents a case of a 31-year-old woman successfully treated medically for a noncommunicating rudimentary horn ectopic pregnancy who presented with a second, successive rudimentary horn pregnancy. Patient underwent laparoscopic excision of right rudimentary horn and right salpingectomy after failed methotrexate therapy. Given the potential for rupture and recurrence, serious efforts ...

In classical, AGM-style belief change, it is assumed that the underlying logic contains classical propositional logic. This is clearly a limiting assumption, particularly in Artificial Intelligence. Consequently there has been recent interest in studying belief change in approaches where the full expressivity of classical propositional logic is not obtained. In this paper we investigate belief ...

Approximating a general formula from above and below by Horn formulas (its Horn envelope and Horn core, respectively) was proposed by Selman and Kautz (1991, 1996) as a form of \knowledge compilation," supporting rapid approximate reasoning; on the negative side, this scheme is static in that it supports no updates, and has certain complexity drawbacks pointed out by Kavvadias, Papadimitriou an...

Given a family of Horn clauses, what is the minimal number of Horn clauses implying all other clauses in the family? What is the maximal number of Horn clauses from the family without having resolvents of a certain kind? We consider various problems of this type, and give some sharp bounds. We also consider the probability that a random family of a given size implies all other clauses in the fa...

In this paper we introduce a new approach for revising and merging consistent Horn formulae under minimal model semantics. Our approach is translation-based in the following sense: we generate a propositional encoding capturing both the syntax of the original Horn formulae (the clauses which appear or not in them) and their semantics (their minimal models). We can then use any classical revisio...