Combining algebraic and set-theoretic specifications

Abstract

Specification frameworks such as B and Z provide power sets and cartesian products as built-in type constructors, and employ a rich notation for defining (among other things) abstract data types using formulae of predicate logic and lambda-notation. In contrast, the so-called algebraic specification frameworks often limit the type structure to sort constants and first-order functionalities, and restrict formulae to (conditional) equations. Here, we propose an intermediate framework where algebraic specifications are enriched with a set-theoretic type structure, but formulae remain in the logic of equational Horn clauses. This combines an expressive yet modest specification notation with simple semantics and tractable proof theory.