Introduction

In computer science one frequently encounters the task of specifying the semantics of a Context-free language. In detail, this means that there is a language L generated by a Context-free grammar and every string w ∈ L has a meaning, called the semantics of w; the semantics is an element of the carrier set of some semantic domain. Let us call the whole machinery which computes the semantics of w the semantics evaluator (Fig. 1.1). A typical occurrence is where L is a programming language, i.e, the strings are programs, and the semantics of a program w is the assembly code which is obtained by translating w into some assembly language.