I.D. Craig, The Formal Specification of a Blackboard Framework (May 1, 1991).
The blackboard architecture is a complex, though powerful, model of problem-solving, and opinions vary as to its interpretation. The use of formal specifications for blackboard systems appears warranted by their complexity, their application in real-time and safety critical domains, and because of the informality of the construct itself. This paper describes the Z specification of a blackboard framework, the aims, and the methods by which it was executed. At present, the specification is only a top-level one (and occupies over 100 A4 pages, including proofs and explanatory text): this has allowed concentration on the interpretation of the architecture, and has allowed the formal proof of a number of properties which have, hitherto, had 'folklore' status. The specification exercise revealed a number of areas in which further work was required. The blackboard specification is one of a number of Z specifications of AI architectures that we have undertaken: the problem areas first identified in the blackboard specification have reappeared in the others, and we suggest ways of solving the problems which are, perhaps, of general utility.