A method for enumerating cosets of a group presented by a canonical system
ISSAC '89 Proceedings of the ACM-SIGSAM 1989 international symposium on Symbolic and algebraic computation
Delay-Insensitivity and Semi-Modularity
Formal Methods in System Design
Using assertions about traces to write abstract specifications for software modules
Software fundamentals
Foundations of the Trace Assertion Method of Module Interface Specification
IEEE Transactions on Software Engineering
Automata, Languages, and Machines
Automata, Languages, and Machines
RTA '89 Proceedings of the 3rd International Conference on Rewriting Techniques and Applications
The impact of requirements changes on specifications and state machines
Software—Practice & Experience
An axiom system for sequence-based specification
Theoretical Computer Science
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It has been shown recently that deterministic semiautomata can be represented by canonical words and equivalences; that work was motivated by the trace-assertion method for specifying software modules. Here, we generalize these ideas to a class of nondeterministic semiautomata. A semiautomaton is settable if, for every state q, there exists a word Wq such that q, and no other state, can be reached from some initial state by a path spelling Wq. We extend many results from the deterministic case to settable nondeterministic semiautomata. Now each word has a number of canonical representatives. We show that a prefix-rewriting system exists for transforming any word to any of its representatives. If the set of canonical words is prefix-continuous (meaning that, if w and a prefix u of w are in the set, then all prefixes of w longer than u are also in the set), the rewriting system has no infinite derivations. Examples of specifications of nondeterministic modules are given.