Internal and External Characterizations of PT-Net Building Block Behavior

摘要

Subnets whose relative boundary consists only of transitions, termed building blocks, are used to structure specifications of distributed systems. The problem of how to determine the effects of a building block on its possible environments, considering only its internal structure, is considered. External equivalence of building blocks allows one to change these components without affecting the behavior of the environment and is thus of practical importance. As there are infinitely many potential environments, external equivalence cannot be expressed in a finite form (nor proven) easily. The contexts in which internal equivalence, which is often obtainable without too much effort, is a sufficient condition for external equivalence are investigated. The approach chosen is to specify the building blocks internally by a set of net languages, and to define internal equivalence as the quality of these specifications. (Copyright (c) GMD 1987.)