Transformations of CCP programs

TL;DR

This paper presents a transformation system for concurrent constraint programming that optimizes programs while preserving semantics, deadlock behavior, and enabling deadlock-freeness proofs, leading to more efficient and reliable concurrent software.

Contribution

The paper introduces a novel transformation system for CCP that guarantees semantic preservation and deadlock analysis, allowing for program optimization and correctness proofs.

Findings

Transformations preserve input/output semantics.

Optimization includes eliminating communication channels and synchronization.

System aids in proving deadlock freeness.

Abstract

We introduce a transformation system for concurrent constraint programming (CCP). We define suitable applicability conditions for the transformations which guarantee that the input/output CCP semantics is preserved also when distinguishing deadlocked computations from successful ones and when considering intermediate results of (possibly) non-terminating computations. The system allows us to optimize CCP programs while preserving their intended meaning: In addition to the usual benefits that one has for sequential declarative languages, the transformation of concurrent programs can also lead to the elimination of communication channels and of synchronization points, to the transformation of non-deterministic computations into deterministic ones, and to the crucial saving of computational space. Furthermore, since the transformation system preserves the deadlock behavior of programs, it can be used for proving deadlock freeness of a given program wrt a class of queries. To this aim it is sometimes sufficient to apply our transformations and to specialize the resulting program wrt the given queries in such a way that the obtained program is trivially deadlock free.