Results 1  10
of
49
Soft Concurrent Constraint Programming
, 2001
"... . Soft constraints extend classical constraints to represent multiple consistency levels, and thus provide a way to express preferences, fuzziness, and uncertainty. While there are many soft constraint solving algorithms, even distributed ones, by now there seems to be no concurrent programming fram ..."
Abstract

Cited by 50 (32 self)
 Add to MetaCart
. Soft constraints extend classical constraints to represent multiple consistency levels, and thus provide a way to express preferences, fuzziness, and uncertainty. While there are many soft constraint solving algorithms, even distributed ones, by now there seems to be no concurrent programming framework where soft constraints can be handled. In this paper we show how the classical concurrent constraint (cc) programming framework can work with soft constraints, and we also propose an extension of cc languages which can use soft constraints to prune and direct the search for a solution. We believe that this new programming paradigm, called soft cc (scc), can be very useful in many webrelated scenarios. In fact, the language level allows web agents to express their interaction and negotiation protocols, and also to post their requests in terms of preferences, and the underlying soft constraint solver can nd an agreement among the agents even if their requests are incompatible. 1
Automatic verification of timed concurrent constraint programs
 TPLP
, 2006
"... The language Timed Concurrent Constraint (tccp) is the extension over time of the Concurrent Constraint Programming (cc) paradigm that allows us to specify concurrent systems where timing is critical, for example reactive systems. Systems which may have an infinite number of states can be specified ..."
Abstract

Cited by 19 (8 self)
 Add to MetaCart
The language Timed Concurrent Constraint (tccp) is the extension over time of the Concurrent Constraint Programming (cc) paradigm that allows us to specify concurrent systems where timing is critical, for example reactive systems. Systems which may have an infinite number of states can be specified in tccp. Model checking is a technique which is able to verify finitestate systems with a huge number of states in an automatic way. In the last years several studies have investigated how to extend model checking techniques to systems with an infinite number of states. In this paper we propose an approach which exploits the computation model of tccp. Constraint based computations allow us to define a methodology for applying a model checking algorithm to (a class of) infinitestate systems. We extend the classical algorithm of model checking for LTL to a specific logic defined for the verification of tccp and to the tccp Structure which we define in this work for modeling the program behavior. We define a restriction on the time in order to get a finite model and then we develop some illustrative examples. To the best of our knowledge this is the first approach that defines a model checking methodology for tccp.
On the Expressive Power of Concurrent Constraint Programming Languages
 IN PPDP 2002
, 2002
"... The tcc paradigm is a formalism for timed concurrent constraint programming. Several tcc languages di#ering in their way of expressing infinite behavior have been proposed in the literature. In this paper ..."
Abstract

Cited by 15 (15 self)
 Add to MetaCart
The tcc paradigm is a formalism for timed concurrent constraint programming. Several tcc languages di#ering in their way of expressing infinite behavior have been proposed in the literature. In this paper
Open Bisimulation for the Concurrent Constraint Picalculus ⋆
"... Abstract. The concurrent constraint picalculus (ccpicalculus) has been introduced as a model for concluding Service Level Agreements. The ccpi calculus combines the synchronous communication paradigm of process calculi with the constraint handling mechanism of concurrent constraint programming. ..."
Abstract

Cited by 11 (0 self)
 Add to MetaCart
Abstract. The concurrent constraint picalculus (ccpicalculus) has been introduced as a model for concluding Service Level Agreements. The ccpi calculus combines the synchronous communication paradigm of process calculi with the constraint handling mechanism of concurrent constraint programming. While in the original presentation of the calculus a reduction semantics has been proposed, in this work we investigate the abstract semantics of ccpi processes. First, we define a labelled transition system of the calculus and a notion of open bisimilarity à la picalculus that is proved to be a congruence. Next, we give a symbolic characterisation of bisimulation and we prove that the two semantics coincide. Essentially, two processes are open bisimilar if they have the same stores of constraints this can be statically checked and if their moves can be mutually simulated. A key idea of the symbolic transition system is to have ‘contextual ’ labels, i.e. labels specifying that a process can evolve only in presence of certain constraints. Finally, we show that the polyadic Explicit Fusions calculus introduced by Gardner and Wischik can be translated into monadic ccpi and that such a transition preserves open bisimilarity. The mapping exploits fusions and tuple unifications as constraints. 1
On the Expressive Power of Temporal Concurrent Constraint Programming Languages
 In Proceedings of the 4th ACM SIGPLAN International Conference on Principles and Practice of Declarative Programming
, 2002
"... The tcc paradigm is a formalism for timed concurrent constraint programming. Several tcc languages differing in their way of expressing infinite behavior have been proposed in the literature. In this paper we study the expressive power of some of these languages. In particular, we show that (1) recu ..."
Abstract

Cited by 10 (1 self)
 Add to MetaCart
The tcc paradigm is a formalism for timed concurrent constraint programming. Several tcc languages differing in their way of expressing infinite behavior have been proposed in the literature. In this paper we study the expressive power of some of these languages. In particular, we show that (1) recursion using procedures with parameters is behaviorally equivalent to parameterless procedures with dynamic scoping, that (2) replication is behaviorally equivalent to parameterless procedures with static scoping, and that (3) the languages from (1) are strictly more expressive than the languages from (2). Furthermore, we show that behavioral equivalence is undecidable for the languages from (1), but decidable for the languages from (2). Both undecidability results hold even if the process variables take values from a fixed finite domain.
The expressivity of universal timed CCP: undecidability of Monadic FLTL and closure operators for security
 IN PPDP ’08: PROCEEDINGS OF THE 10TH INTERNATIONAL ACM SIGPLAN CONFERENCE ON PRINCIPLES AND PRACTICE OF DECLARATIVE PROGRAMMING
, 2008
"... The timed concurrent constraint programing model (tcc) is a declarative framework, closely related to FirstOrder Linear Temporal Logic (FLTL), for modeling reactive systems. The universal tcc formalism (utcc) is an extension of tcc with the ability to express mobility. Here mobility is understood a ..."
Abstract

Cited by 10 (6 self)
 Add to MetaCart
The timed concurrent constraint programing model (tcc) is a declarative framework, closely related to FirstOrder Linear Temporal Logic (FLTL), for modeling reactive systems. The universal tcc formalism (utcc) is an extension of tcc with the ability to express mobility. Here mobility is understood as communication of private names as typically done for mobile systems and security protocols. This paper is devoted to the study of 1) the expressiveness of utcc and 2) its semantic foundations. As applications of this study, we also state 3) a noteworthy decidability result for the wellestablished framework of FLTL and 4) bring new semantic insights into the modeling of security protocols. More precisely, we show that in contrast to tcc, utcc is Turingpowerful by encoding Minsky machines. The encoding uses a monadic constraint system allowing us to prove a new result for a fragment of FLTL: The undecidability of the validity problem for monadic FLTL without equality and function symbols. This result refutes a decidability conjecture for FLTL from a previous paper. It also justifies the restriction imposed in previous decidability results on the quantification of flexiblevariables. We shall also show that as in tcc, utcc processes can be semantically represented as partial closure operators. The representation is fully abstract wrt the inputoutput behavior of processes for a meaningful fragment of the utcc. This shows that mobility can be captured as closure operators over an underlying constraint system. As an application we identify a language for security protocols that can be represented as closure operators over a cryptographic constraint system.
Timed Constraint Programming: A Declarative Approach to Usage Control
"... This paper focuses on policy languages for (rolebased) access control [14, 32], especially in their modern incarnations in the form of trustmanagement systems [9] and usage control [30, 31]. Any (declarative) approach to access control and trust management has to address the following issues: . ..."
Abstract

Cited by 9 (0 self)
 Add to MetaCart
This paper focuses on policy languages for (rolebased) access control [14, 32], especially in their modern incarnations in the form of trustmanagement systems [9] and usage control [30, 31]. Any (declarative) approach to access control and trust management has to address the following issues: .
A system of interactive scores based on Petri nets
"... Abstract — We propose a formalism for composition and performance of musical pieces involving temporal structures and discrete interactive events. We use the Allen relations to constrain these structures and to partially define a temporal order on them. During the score composition stage, we use a c ..."
Abstract

Cited by 7 (4 self)
 Add to MetaCart
Abstract — We propose a formalism for composition and performance of musical pieces involving temporal structures and discrete interactive events. We use the Allen relations to constrain these structures and to partially define a temporal order on them. During the score composition stage, we use a constraints propagation model to maintain the temporal relations between the structures. For the performance stage, we must allow the composer to trigger the interactive events “whenever ” he wants and we have to also maintain the temporal relations in a realtime context. We use a model based on Petri nets for this stage. We also provide a solution to define global constraints in addition of the local temporal constraints inspired by the NTCC formalism. I.
Formalizing Timed Musical Processes with a Temporal Concurrent Constraint Programming Calculus
 In Proc. of Musical Constraints Workshop CP2001
, 2001
"... We propose the ntcc calculus, a model of temporal concurrent constraint programming with the capability of modeling asynchronous and nondeterministic timed behavior, as a convenient formalism for expressing temporal musical processes. We argue that ntcc provides a simple yet powerful framework ..."
Abstract

Cited by 6 (3 self)
 Add to MetaCart
We propose the ntcc calculus, a model of temporal concurrent constraint programming with the capability of modeling asynchronous and nondeterministic timed behavior, as a convenient formalism for expressing temporal musical processes. We argue that ntcc provides a simple yet powerful framework for expressing a rich variety of musical events coordination. We illustrate its potential by formalizing in ntcc a musical improvisation process. We describe a proof system for linear temporal properties of ntcc processes and show its use for proving properties of musical processes.