Abstract

Felicitous models were defined by Kit Fine in 1987 for the purpose of describing the semantics of negation in the programming language Prolog. They are often referred to as stable models, or answer sets. Years later, sophisticated software systems for generating answer sets were designed, and they became the basis of a new programming paradigm, called answer set programming. That programming method is used now for solving computational problems in many areas of science and technology. This chapter traces the early history of felicitous models and the ways in which that idea contributed to computer science.