Hybrid Behaviour of Markov Population Models

We investigate the behaviour of population models written in Stochastic Concurrent Constraint Programming (sCCP), a stochastic extension of Concurrent Constraint Programming. In particular, we focus on models from which we can define a semantics of sCCP both in terms of Continuous Time Markov Chains (CTMC) and in terms of Stochastic Hybrid Systems, in which some populations are approximated continuously, while others are kept discrete. We will prove the correctness of the hybrid semantics from the point of view of the limiting behaviour of a sequence of models for increasing population size. More specifically, we prove that, under suitable regularity conditions, the sequence of CTMC constructed from sCCP programs for increasing population size converges to the hybrid system constructed by means of the hybrid semantics. We investigate in particular what happens for sCCP models in which some transitions are guarded by boolean predicates or in the presence of instantaneous transitions

Observational equivalences for linear logic CC languages

Linear logic Concurrent Constraint programming (LCC) is an extension of concurrent constraint programming (CC) where the constraint system is based on Girard's linear logic instead of the classical logic. In this paper we address the problem of program equivalence for this programming framework. For this purpose, we present a structural operational semantics for LCC based on a label transition system and investigate different notions of observational equivalences inspired by the state of art of process algebras. Then, we demonstrate that the asynchronous \pi-calculus can be viewed as simple syntactical restrictions of LCC. Finally we show LCC observational equivalences can be transposed straightforwardly to classical Concurrent Constraint languages and Constraint Handling Rules, and investigate the resulting equivalences.Comment: 17 page

A Concurrent Operational Semantics for Constraint Functional Logic Programming

In this paper we describe a sound and complete concurrent operational semantics for constraint functional logic programming languages which allows to model declarative applications in which the interaction between demand-driven narrowing and constraint solving helps to prune the search space, leading to shorter goal derivations. We encode concurrency into the generic CFLP(D) scheme, a uniform foundation for the operational semantics of constraint functional logic programming systems parameterized by a constraint solver over the given domain D. In this concurrent version of the CFLP(D) scheme, goal solving processes can be executed concurrently and cooperate together to perform their specific tasks via demand-driven narrowing and declarative residuation guided by constrained definitional trees, constraint solving, and communication by synchronization on logical variables

A process algebra for synchronous concurrent constraint programming

Concurrent constraint programming is classically based on asynchronous communication via a shared store. This paper presents new version of the ask and tell primitives which features synchronicity. Our approach is based on the idea of telling new information just in the case that a concurrently running process is asking for it. An operational and an algebraic semantics are defined. The algebraic semantics is proved to be sound and complete with respect to a compositional operational semantics which is also presented in the paper

A Rewriting Logic Approach to Stochastic and Spatial Constraint System Specification and Verification

This paper addresses the issue of specifying, simulating, and verifying reactive systems in rewriting logic. It presents an executable semantics for probabilistic, timed, and spatial concurrent constraint programming ---here called stochastic and spatial concurrent constraint systems (SSCC)--- in the rewriting logic semantic framework. The approach is based on an enhanced and generalized model of concurrent constraint programming (CCP) where computational hierarchical spaces can be assigned to belong to agents. The executable semantics faithfully represents and operationally captures the highly concurrent nature, uncertain behavior, and spatial and epistemic characteristics of reactive systems with flow of information. In SSCC, timing attributes ---represented by stochastic duration--- can be associated to processes, and exclusive and independent probabilistic choice is also supported. SMT solving technology, available from the Maude system, is used to realize the underlying constraint system of SSCC with quantifier-free formulas over integers and reals. This results in a fully executable real-time symbolic specification that can be used for quantitative analysis in the form of statistical model checking. The main features and capabilities of SSCC are illustrated with examples throughout the paper. This contribution is part of a larger research effort aimed at making available formal analysis techniques and tools, mathematically founded on the CCP approach, to the research community.Comment: arXiv admin note: text overlap with arXiv:1805.0743

Abstract Analysis of Universal Properties for tccp

[EN] The Timed Concurrent Constraint Language (tccp) is a time extension of the concurrent constraint paradigm of Saraswat. tccp was defined to model reactive systems, where infinite behaviors arise naturally. In previous works, a semantic framework and abstract diagnosis method for the language has been defined. On the basis of that semantic framework, this paper proposes an abstract semantics that, together with a widening operator, is suitable for the definition of different analyses for tccp programs. The abstract semantics is correct and can be represented as a finite graph where each node represents a hypothetical computational step of the program containing approximated information for the variables. The widening operator allows us to guarantee the convergence of the abstract fixpoint computation.This work has been supported by the Andalusian Excellence Project P11-TIC7659. This work has been partially supported by the EU (FEDER) and the Spanish MINECO under grant TIN 2013-45732-C4-1-P (DAMAS) and by Generalitat Valenciana PROMETEOII/2015/013Comini, M.; Gallardo Melgarejo, MDM.; Titolo, L.; Villanueva, A. (2015). Abstract Analysis of Universal Properties for tccp. Lecture Notes in Computer Science. 163-178. https://doi.org/10.1007/978-3-319-27436-2_10S163178Alpuente, M., Gallardo, M.M., Pimentel, E., Villanueva, A.: A semantic framework for the abstract model checking of tccp programs. Theor. Comput. Sci. 346(1), 58–95 (2005)Bagnara, R., Hill, P.M., Ricci, E., Zaffanella, E.: Precise widening operators for convex polyhedra. Sci Comput. Program. 58(1–2), 28–56 (2005)Comini, M., Titolo, L., Villanueva, A.: Abstract diagnosis for timed concurrent constraint programs. Theor. Pract. Log. Program. 11(4–5), 487–502 (2011)Comini, M., Titolo, L., Villanueva, A.: A condensed goal-independent bottom-up fixpoint modeling the behavior of tccp. Technical report, DSIC, Universitat Politècnica de València (2013). http://riunet.upv.es/handle/10251/34328Cousot, P., Cousot, R.: Abstract Interpretation: a unified lattice model for static analysis of programs by construction or approximation of fixpoints. In: Proceedings of the 4th ACM SIGACT-SIGPLAN Symposium on Principles of Programming Languages, Los Angeles, California, January 17–19, pp. 238–252. ACM Press, New York (1977)de Boer, F.S., Gabbrielli, M., Meo, M.C.: A timed concurrent constraint language. Inf. Comput. 161(1), 45–83 (2000)Falaschi, M. Gabbrielli, M., Marriott, K., Palamidessi, C.: Compositional analysis for concurrent constraint programming. In: Proceedings of the Eighth Annual IEEE Symposium on Logic in Computer Science, pp. 210–221. IEEE Computer Society Press, Los Alamitos (1993)Falaschi, M., Olarte, C., Palamidessi, C.: Abstract interpretation of temporal concurrent constraint programs. Theor. Pract. Log. Program. (TPLP) 15(3), 312–357 (2015)Falaschi, M., Villanueva, A.: Automatic verification of timed concurrent constraint programs. Theor. Pract. Log. Program. 6(3), 265–300 (2006)Saraswat, V.A.: Concurrent Constraint Programming. The MIT Press, Cambridge (1993)Zaffanella, E., Giacobazzi, R., Levi, G.: Abstracting synchronization in concurrent constraint programming. J. Funct. Log. Program. 6, 1997 (1997

Connectors meet Choreographies

We present Cho-Reo-graphies (CR), a new language model that unites two powerful programming paradigms for concurrent software based on communicating processes: Choreographic Programming and Exogenous Coordination. In CR, programmers specify the desired communications among processes using a choreography, and define how communications should be concretely animated by connectors given as constraint automata (e.g., synchronous barriers and asynchronous multi-casts). CR is the first choreography calculus where different communication semantics (determined by connectors) can be freely mixed; since connectors are user-defined, CR also supports many communication semantics that were previously unavailable for choreographies. We develop a static analysis that guarantees that a choreography in CR and its user-defined connectors are compatible, define a compiler from choreographies to a process calculus based on connectors, and prove that compatibility guarantees deadlock-freedom of the compiled process implementations

A program analysis framework for tccp based on abstract interpretation

[EN] The timed concurrent constraint language (tccp) is a timed extension of the concurrent constraint paradigm. tccp was defined to model reactive systems, where infinite behaviors arise naturally. In previous works, a semantic framework and abstract diagnosis method for the language have been defined. On the basis of that semantic framework, this paper proposes an abstract semantics that, together with a widening operator, is suitable for the definition of different analyses for tccp programs. The abstract semantics is correct and can be represented as a finite graph where each node represents a hypothetical (abstract) computational step of the program. The widening operator allows us to guarantee the convergence of the abstract fixpoint computation.This author has been supported by the Andalusian Excellence Project P11-TIC-7659. This work has been partially supported by the EU (FEDER) and the Spanish MINECO under grants TIN 2015-69175-C4-1-R and TIN 2013-45732-C4-1-P and by Generalitat Valenciana PROMETEOII/2015/013Comini, M.; Gallardo, M.; Titolo, L.; Villanueva, A. (2017). A program analysis framework for tccp based on abstract interpretation. Formal Aspects of Computing. 29(3):531-557. https://doi.org/10.1007/s00165-016-0409-8S531557293Alpuente M, Gallardo MM, Pimentel E, Villanueva A (2006) A semantic framework for the abstract model checking of tccp programs. Theor Comput Scie 346(1): 58–95Bagnara R, Hill PM., Ricci E, Zaffanella E (2005) Precise widening operators for convex polyhedra. Sci Comput Program 58(1–2):28–56Cousot P, Cousot R (1977) Abstract interpretation: a unified lattice model for static analysis of programs by construction or approximation of fixpoints. In: Proceedings of the 4th ACM SIGACT-SIGPLAN symposium on principles of programming languages, Los Angeles, California, January 17–19. ACM Press, New York, pp 238–252Clarke EM, Grumberg O, Jha S, Lu Y, Veith H (2000) Counterexample-guided abstraction refinement. In: CAV, Lecture Notes in Computer Science, vol 1855. Springer, pp 154–169Comini M, Gallardo MM, Titolo L, Villanueva A (2015) Abstract Analysis of Universal Properties for tccp. In: Falaschi M (ed) Logic-based Program Synthesis and Transformation, 25th International Symposium, LOPSTR 2015. Revised Selected Papers, Lecture Notes in Computer Science, vol 9527. Springer, pp 163–178Comini M, Titolo L, Villanueva A (2011) Abstract diagnosis for timed concurrent constraint programs. Theory Pract Logic Programm 11(4-5):487–502Comini M, Titolo L, Villanueva A (2013) A condensed goal-independent bottom-up fixpoint modeling the behavior of tccp. Technical report, DSIC, Universitat Politècnica de València. http://riunet.upv.es/handle/10251/34328de Boer FS, Gabbrielli M, Meo MC (2000) A timed concurrent constraint language. Inf Comput 161(1): 45–83Falaschi M, Gabbrielli M, Marriott K, Palamidessi C (1993) Compositional analysis for concurrent constraint programming. In: Proceedings of the eighth annual IEEE symposium on logic in computer science, Los Alamitos, CA, USA, IEEE Computer Society Press, pp 210–221Falaschi M, Olarte C, Palamidessi C (2015) Abstract interpretation of temporal concurrent constraint programs. Theory and Pract Logic Program (TPLP) 15(3): 312–357Falaschi M, Villanueva A (2006) Automatic verification of timed concurrent constraint programs. Theory Pract Logic Program 6(3): 265–300Gallardo MM, Merino P, Pimentel E (2002) Refinement of LTL formulas for abstract model checking. In: Static analysis, 9th international symposium, SAS 2002, Madrid, Spain, September 17–20, 2002, Proceedings, pp 395–410Saraswat VA (1993) Concurrent constraint programming. The MIT Press, CambridgeSaraswat VA, Rinard M, Panangaden P (1991) The semantic foundations of concurrent constraint programming. In: Proceedings of the 18th ACM SIGPLAN-SIGACT symposium on principles of programming languages. ACM, New York, pp 333–352Zaffanella E, Giacobazzi R, Levi G (1997) Abstracting synchronization in concurrent constraint programming. J Funct Logic Program (6