Operational Semantics of IMP

This chapter introduces the formal syntax and operational semantics of a simple, structured imperative language called IMP, with static variable allocation and no sophisticated declaration constructs for data types, functions, classes, methods and the like. The operational semantics is defined in the natural style and it assumes an abstract machine with a very basic form of memory to associate integer values with variables. The operational semantics is used to derive a notion of program equivalence and several examples of (in)equivalence proofs are shown.