Behavioural Specification for Hierarchical Object Composition 

Behavioural specification based on hidden (sorted) algebra constitutes one of the most promising recently developed formal specification and verification paradigms for system development.
Here we formally introduce novel concepts of behavioural object and equivalence between behavioural objects within the hidden algebra framework. We formally define several object composition operators on behavioural objects corresponding to the hierarchical object composition methodology introduced by CafeOBJ. We study their basic semantical properties and show that our most general form of behavioural object composition with synchronisation has final semantics and a composability property of behavioural equivalence supporting a high reusability of verifications. We also show the commutativity and the associativity of parallel compositions without synchronisation.

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