A compositional comparison of specifications of the alternating bit protocol in CCS and UNITY based on algebra transformation systems

. Algebra transformation systems (ATS) are introduced as a common semantical framework in which specifications written in different languages can be interpreted and formally compared. An ATS is a two layered structure given by a transitions system modeling the behaviour of a system and a data level containing the associated data states and their transformations. This structure allows for the interpretation of behavioural as well as state based specifications. In this framework refinements and composition operations are investigated, and a general result on refinements of composed specifications induced by compatible local refinements is shown. As an example two specifications of the alternating bit protocol are compared, one given in the process calculus CCS, the other one in the parallel programming language UNITY. 1 Introduction The task of integrating formal specification techniques can be understood in two different ways. In a stricter sense the aim of the integration ..