Yet Another Characterization of Strong Equivalence

Strong equivalence of disjunctive logic programs is characterized here by a calculus that operates with syntactically simple formulas

Causal reasoning from almost first principles

A formal theory of causal reasoning is presented that encompasses both Pearl's approach to causality and several key formalisms of nonmonotonic reasoning in Artificial Intelligence. This theory will be derived from a single rationality principle of causal acceptance for propositions. However, this principle will also set the theory of causal reasoning apart from common representational approaches to reasoning formalisms

Enhanced Contraction and (In)dependence Preliminary report

We introduce a number of contraction operations that allow us to preserve more information in the process of belief contraction and revision of our epistemic states. One of them, choice contraction, will be argued to characterise basic (in)dependence relations among propositions belonging to the epistemic state

A Logical Foundation for Logic Programming II: Semantics of General Logic Programs

We suggested in [12] a general logical formalism for Logic Programming based on a four-valued inference. In this paper we give a uniform representation of various semantics for logic programs based on this formalism. The main conclusion from this representation is that the distinction between these semantics can be largely attributed to the difference in their underlying (monotonic) logical systems. Moreover, in most cases the difference can even be reduced to that of the language, that is, to the difference in the logical connectives allowed for representing derivable information. Keywords. Foundations of logic programming, negation as failure, semantics for logic programs, nonmonotonic reasoning. 1 Introduction This is a second part of the study of a general logical formalism for logic programming (see [12]). Briefly, the formalism, called biconsequence relations, involves rules (bisequents) of the form a : b fl c : d that serve as direct representations of program rules of a most ..