Examples of formal semantics

A technique of formal definition, based on relations between "attributes" associated with nonterminal symbols in a context-free grammar, is illustrated by several applications to simple, yet typical, problems. First we define the basic properties of lambda expressions, involving substitution and renaming of bound variables. Then a simple programming language is defined using several different points of view. The emphasis is on "declarative" rather than "imperative" or "algorithmic" forms of definition.