Concurrent constraint programming

Abstract

This paper presents a new and very rich class of (concurrent) programming languages, based on the notion of comput.ing with parhal information, and the concommitant notions of consistency and entailment.' In this framework, computation emerges from the interaction of concurrently executing agents that communicate by placing, checking and instantiating constraints on shared variables. Such a view of computation is interesting in the context of programming languages because of the ability to represent and manipulate partial information about the domain of discourse, in the context of concurrency because of the use of constraints for communication and control, and in the context of AI because of the availability of simple yet powerful mechanisms for controlling inference, and the promise that very rich representational/programming languages, sharing the same set of abstract properties, may be possible.

CC-Pi: A Constraint-Based Language for Specifying Service Level Agreements

“…They are analogous to the corresponding definitions given by Saraswat and Rinard [15]. Below we abbreviate by (×C) the product c 1 × .…”

“…Encoding cc programming First, we briefly recall cc programming [15]. For the purpose of a more straightforward translation into cc-pi, we present a slightly modified version of the language.…”

“…The last, important difference with respect to [15] is that we handle variables, or rather names, in a very different way. In ordinary cc programming, constraints involving variables are seen as relations, in the style of Tarski's cylindrical algebras.…”

Constraint design rewriting

“…Here the key issue is that nodes of the graphs can be considered at the same time as names in the π-calculus sense (thus representing, channels, links, continuations, security keys) and as variables required to satisfy constraints involving functional and quality of service restrictions. As future work, indeed, we may consider design development procedures in the style of concurrent constraint programming [15] where (possibly concurrent) agents act on the same constraint network design applying productions in a consistent way with tell -like operations whose effect is that of applying a refinement of the design (replacing a variable or constant in a design term by another term of the same sort).…”

A Practical Formal Model for Safety Analysis in Capability-Based Systems

“…New knowledge can increase a subject's readiness to collaborate and successful collaboration (propagation of information and access) can provide new access to data and capabilities, and can provide new knowledge about the subject's environment. By forcing monotonic evolution of knowledge and access we inherit the rich semantics of Concurrent Constraint Programming (CPP) [Sar93] and the expressiveness that comes with it. A conditional collaboration is an ask operation, waiting in its own thread until the condition is either entailed or disentailed by the constraint store.…”