Fixpoint semantics for logic programming -- a survey
; Dept. Mathematics and Computer Science; Lehman College (CUNY); Depts. Computer Science, Philosophy, Mathematics
; Bronx, NY 10468-1589; Graduate Center (CUNY), 365 Fifth Avenue, NYC, NY 10016-4309
The variety of semantical approaches that have been invented for logic programs is quite broad, drawing on classical and many-valued logic, lattice theory, game theory, and topology. One source of this richness is the inherent non-monotonicity of its negation, something that does not have close parallels with the machinery of other programming paradigms. Nonetheless, much of the work on logic programming semantics seems to exist side by side with similar work done for imperative and functional programming, with relatively minimal contact between communities. In this paper we summarize one variety of approaches to the semantics of logic programs: that based on fixpoint theory. We do not attempt to cover much beyond this single area, which is already remarkably fruitful. We hope readers will see parallels with, and the divergences from the better known fixpoint treatments developed for other programming methodologies.