A CONFLUENT SEMANTIC BASIS FOR THE ANALYSIS OF CONCURRENT CONSTRAINT LOGIC PROGRAMS

The standard operational semantics of concurrent constraint logic lang uages is not confluent in the sense that different schedulings of proc esses may result in different program behaviors, While implementations are free to choose specific scheduling policies, analyses should be c orrect for all implementations, Moreover, in the presence of paralleli sm, it is usually not possible to determine how processes will actuall y be scheduled. Efficient program analysis is therefore difficult as a ll process schedulings must be considered. To overcome this problem, w e introduce a confluent semantics which closely approximates the stand ard (nonconfluent) semantics. This semantics provides a basis for effi cient and accurate program analysis for these languages, To illustrate the usefulness of this approach, we sketch analyses based on abstract interpretations of the confluent semantics which determine if a progr am is suspension- and local suspension-free. (C) Elsevier Science Inc. , 1997