Declarative Semantics

This chapter presents the declarative semantics of logic programs. After a brief introduction, the basic syntax and terminology of logic programs is introduced. We then discuss interpretations and models of logic programs. These provide the declarative semantics. Then the key concept of a correct answer substitution is introduced. This provides a declarative understanding of the desired output from a program and a goal. The basic fixpoint results are then proved and the chapter culminates with a fixpoint characterization of the least Herbrand model of a program.