Much ado – and increased complexity – is generally the case when it comes to checking formally the (intended) meaning of programs, as formal semantics for programs are typically extrinsic to both them and the formal grammars that generate the programming languages in which they are written. The van Wijngaarden grammars, on the contrary, have an intrinsic semantics in the sense that their rules contain or express the (intended) meaning of the terminal strings generated by them. This intrinsicness allows for (...) preservation of meaning both in syntactic change and context-sensitive conditions. In order better to show the intrinsicness of the semantics of the van Wijngaarden grammars I contrast them with the attribute grammars, a frequent choice when the semantic analysis of programming languages is called for (e.g., in compilation). (shrink)

Knowledge representation (KR) is actually more than representation: It involves also inference, namely inference of “new” knowledge, i.e. new facts. Logic programming is a suitable KR medium, but more often than not discussions on this programming paradigm focus on aspects other than KR. In this paper, I elaborate on the general theory of logic programming and give the essentials of two of its main implementations, to wit, Prolog and Datalog, from the viewpoint of deductive computing over knowledge bases, which includes (...) deductive programming. (shrink)