Prolegomena to Logic Programming for Non-monotonic Reasoning Prolegomena to Logic Programming for Non{monotonic Reasoning

The present prolegomena consist, as all indeed do, in a critical discussion serving to introduce and interpret the extended works that follow in this book. As a result, the book is not a mere collection of excellent papers in their own specialty, but provides also the basics of the motivation, background history, important themes, bridges to other areas, and a common technical platform of the principal formalisms and approaches, augmented with examples. In the introduction we whet the reader's interest in the eld of logic programming and non{monotonic reasoning with the promises it ooers and with its outstanding problems too. There follows a brief historical background to logic programming, from its inception to actuality, and its relationship to non{monotonic formalisms, stressing its semantical and procedural aspects. The next couple of sections provide motivating examples and an overview of the main semantics paradigms for normal programs (stable models and well{founded) and for extended logic programs (answer{sets, e{answer{ sets, Nelson's strong negation, and well{founded semantics with pseudo and with explicit negation). A subequent section is devoted to disjunctive logic programs and its various semantical proposals. To conclude, a nal section on implementation gives pointers to available systems and their sites. We leave out important concerns, such as paraconsistent semantics, contradiction removal, and updates. Hopefully they will be included in the next book in this series. But an extensive set of references allows the reader to delve into the specialized literature. For other recent relevant complementary overviews in this area we refer to AP96,BDK97,BD96b,Min96,Dix95c].