Exceptions for Algebraic Specifications: On the Meaning of "but"

Schobbens, P.-Y., Exceptions for algebraic specifications: on the meaning of “but”, Science of Computer Programming 20 (1993) 73-111. When building large specifications from requirements, the structure of the specification becomes a central problem: the specification language should allow a decomposition that closely reflects the structure of requirements. In this paper, we propose a decomposition into defaults (general rules) and exceptions to these general rules that fits the requirements found in some application domains. It is complementary, and builds upon, the modular decomposition proposed by the algebraic specification school. Its definition is based on abstract model theorv. leading to the definition of default institutions.