The Experts below are selected from a list of 246 Experts worldwide ranked by ideXlab platform

Andrew E. Santosa - One of the best experts on this subject based on the ideXlab platform.

  • SAC - Concurrent and distributed programming using Constraint logic programs
    Proceedings of the 2004 ACM symposium on Applied computing - SAC '04, 2004
    Co-Authors: Rafael Ramirez, Andrew E. Santosa
    Abstract:

    We describe a coordination language for high-level distributed programming. Its roots are in concurrent Constraint programming where there is a shared Constraint Store and synchronization is achieved via Constraint entailment. A system is modeled as: (a) a set of processes, and (b) a set of Constraints which capture the concurrent behavior of the system. The key advantages are that (1) there is a clear separation of the concurrency and the functionality aspects of the system, (2) processes are coordinated explicitly by a declarative formalism, i.e. Constraints, and (3) the processes-agents are programming language independent.

  • PaCT - Event Logic Programming
    Lecture Notes in Computer Science, 2001
    Co-Authors: Rafael Ramirez, Andrew E. Santosa
    Abstract:

    Wepresent a new concurrent (Constraint) logic programming language based on partially ordered event structures. A system is modeled as: (a) a set of concurrent processes, which are Prolog programs extended with event goals declaring program points of interest, and (b) a Constraint Store which imposes restrictions on the event goals execution order. The Constraint Store acts as a coordination entity which on the one hand encapsulates the system synchronization requirements, and on the other hand, provides a declarative specification of the system concurrency issues. This produces a powerful formalism which at the same time, overcome the deficiencies of traditional concurrent logic programming languages and preserve the benefits of declarative programming.

  • ICECCS - Concurrent programming made easy
    Proceedings Sixth IEEE International Conference on Engineering of Complex Computer Systems. ICECCS 2000, 1
    Co-Authors: Rafael Ramirez, Andrew E. Santosa, Roland H. C. Yap
    Abstract:

    The task of programming concurrent systems is substantially more difficult than the task of programming sequential systems with respect to both correctness and efficiency. In this paper we describe a Constraint-based methodology for writing concurrent applications. A system is modeled as: (a) a set of processes containing a sequence of "markers" denoting the processes points of interest; and (b) a Constraint Store. Process synchronization is specified by incrementally adding Constraints on the markers execution order into the Constraint Store. The Constraint Store contains a declarative specification based on a temporal Constraint logic program. The Store, thus, acts as a coordination entity which on the one hand encapsulates the system synchronization requirements, and on the other hand, provides a declarative specification of the system concurrency issues. This provide great advantages in writing concurrent programs and manipulating them while preserving correctness.

  • IPDPS - A methodology for concurrent and distributed Java applications
    Proceedings International Parallel and Distributed Processing Symposium, 1
    Co-Authors: Rafael Ramirez, Andrew E. Santosa
    Abstract:

    In this paper we describe a Constraint-based methodology for writing concurrent and distributed Java applications. A system is modeled as: (a) a set of Java threads containing a sequence of markers, denoting the threads points of interest; and (b) a Constraint Store. The key advantages are that there is a clear separation of the concurrency aspects of the system's threads from the threads functionality, and threads are coordinated by a formal Constraint-based specification. The treatment of the concurrency issues as orthogonal to the rest of the code allows programmers to independently develop one component from the other, and the declarative nature of the coordination mechanism provides a natural framework for formal verification, synthesis and transformation of concurrent Java programs.

Francesco Santini - One of the best experts on this subject based on the ideXlab platform.

  • a secure non monotonic soft concurrent Constraint language
    Fundamenta Informaticae, 2014
    Co-Authors: Stefano Bistarelli, Francesco Santini
    Abstract:

    We present a fine-grained security model to enforce the access control on the shared Constraint Store in Concurrent Constraint Programming (CCP) languages. We show the model for a non-monotonic version of Soft CCP (SCCP), that is an extension of CCP where the Constraints have a preference level associated with them. Crisp Constraints can be modeled in the same framework as well. In the considered non-monotonic soft version (NmSCCP), it is also possible to remove Constraints from the Store. The language can be used for coordinating agents on a common Store of information that represents the set of shared resources. In such scenarios, it is clearly important to enforce the integrity and confidentiality rights on the resources, in order, for instance, to hide part of the information to some agents, or to prevent an agent to consume too many resources. Finally, we present a bisimulation relation to check equivalence between two programs written in this language.

  • SEFM - Securely accessing shared resources with concurrent Constraint programming
    Software Engineering and Formal Methods, 2012
    Co-Authors: Stefano Bistarelli, Francesco Santini
    Abstract:

    We present a fine-grained security model to enforce the access control on the shared Constraint Store in Concurrent Constraint Programming (CCP) languages. We show the model for a nonmonotonic version of Soft CCP (SCCP), that is an extension of CCP where the Constraints have a preference level associated with them. Crisp Constraints can be modeled in the same framework as well. In the considered nonmonotonic soft version (NmSCCP), it is also possible to remove Constraints from the Store. The language can be used for coordinating agents on a common Store of information that represents the set of shared resources. In such scenarios, it is clearly important to enforce the integrity and confidentiality rights on the resources, in order, for instance, to hide part of the information to some agents, or to prevent an agent to consume too many resources.

  • SAC - A secure coordination of agents with nonmonotonic soft Concurrent Constraint Programming
    Proceedings of the 27th Annual ACM Symposium on Applied Computing - SAC '12, 2012
    Co-Authors: Stefano Bistarelli, Paola Campli, Francesco Santini
    Abstract:

    We present a fine-grained security model to enforce the access control on the Constraint Store in Concurrent Constraint Programming (CCP) languages. We show the model for a nonmonotonic version of Soft CCP (SCCP), that is an extension of CCP which deals with soft Constraints, which are Constraints that have a preference level associated to them. In the considered nomonotonic version (NMSCCP), the language is equipped with actions that can also remove Constraints from the Store. The language can be used for coordinating the agents on a common Store of information. Clearly, in such scenario, is important to enhance the operations that the agents may perform with security and privacy, in order to limit their behavior, e.g., to hide some information or to prevent an agent to consume too many resources.

  • a nonmonotonic soft concurrent Constraint language to model the negotiation process
    Fundamenta Informaticae, 2011
    Co-Authors: Stefano Bistarelli, Francesco Santini
    Abstract:

    We present an extension of the Soft Concurrent Constraint language that allows the non-monotonic evolution of the Constraint Store. To accomplish this, we introduce some new operations: retract(c) reduces the current Store by c, update X(c) transactionally relaxes all the Constraints of the Store that deal with the variables in the set X, and then adds a Constraint c; nask(c) tests if c is not entailed by the Store. The new retraction operators also permit to reason about Belief Revision, i.e. the process of changing beliefs to take into account a new piece of information. We present this framework as a possible solution to the negotiation of resources (e.g. web services and network resource allocation) that need a given Quality of Service (QoS). For this reason we also show the the new operators of the language satisfy the Belief Revision postulates [20], which can be used in the negotiation process. The QoS requirements (expressed as semiring levels) of all the parties should converge on a formal agreement through a negotiation process, which specifies the contract that must be enforced.

  • a nonmonotonic soft concurrent Constraint language for sla negotiation
    Electronic Notes in Theoretical Computer Science, 2009
    Co-Authors: Stefano Bistarelli, Francesco Santini
    Abstract:

    We present an extension of the Soft Concurrent Constraint language that allows the nonmonotonic evolution of the Constraint Store. To accomplish this, we introduce some new operations: the retract(c) reduces the current Store by c, the update"X(c) transactionally relaxes all the Constraints of the Store that deal with the variables in the set X, and then adds a Constraint c; the nask(c) tests if c is not entailed by the Store. We present this framework as a possible solution to the management of resources (e.g. web services and network resource allocation) that need a given Quality of Service (QoS). The QoS requirements of all the parties should converge, through a negotiation process, on a formal agreement defined as the Service Level Agreement, which specifies the contract that must be enforced. c-semirings are the algebraic structures that we use to model QoS metrics.

Ian Horrocks - One of the best experts on this subject based on the ideXlab platform.

  • owl a description logic based ontology language
    International Conference on Logic Programming, 2005
    Co-Authors: Ian Horrocks
    Abstract:

    We present a version of the CCP paradigm, which is both distributed and probabilistic. We consider networks with a fixed number of nodes, each of them possessing a local and independent Constraint Store. While locally the computations evolve asynchronously, following the usual rules of (probabilistic) CCP, the communications among different nodes are synchronous. There are channels, and through them different objects can be exchanged: Constraints, agents and channel themselves. In addition, all this activities are embedded in a probabilistic scheme based on a discrete model of time, both locally and globally. Finally we enhance the language with the capability of performing an automatic remote synchronization of variables belonging to different Constraint Stores.

  • ICLP - OWL: a description logic based ontology language
    Logic Programming, 2005
    Co-Authors: Ian Horrocks
    Abstract:

    We present a version of the CCP paradigm, which is both distributed and probabilistic. We consider networks with a fixed number of nodes, each of them possessing a local and independent Constraint Store. While locally the computations evolve asynchronously, following the usual rules of (probabilistic) CCP, the communications among different nodes are synchronous. There are channels, and through them different objects can be exchanged: Constraints, agents and channel themselves. In addition, all this activities are embedded in a probabilistic scheme based on a discrete model of time, both locally and globally. Finally we enhance the language with the capability of performing an automatic remote synchronization of variables belonging to different Constraint Stores.

Rafael Ramirez - One of the best experts on this subject based on the ideXlab platform.

  • SAC - Concurrent and distributed programming using Constraint logic programs
    Proceedings of the 2004 ACM symposium on Applied computing - SAC '04, 2004
    Co-Authors: Rafael Ramirez, Andrew E. Santosa
    Abstract:

    We describe a coordination language for high-level distributed programming. Its roots are in concurrent Constraint programming where there is a shared Constraint Store and synchronization is achieved via Constraint entailment. A system is modeled as: (a) a set of processes, and (b) a set of Constraints which capture the concurrent behavior of the system. The key advantages are that (1) there is a clear separation of the concurrency and the functionality aspects of the system, (2) processes are coordinated explicitly by a declarative formalism, i.e. Constraints, and (3) the processes-agents are programming language independent.

  • PaCT - Event Logic Programming
    Lecture Notes in Computer Science, 2001
    Co-Authors: Rafael Ramirez, Andrew E. Santosa
    Abstract:

    Wepresent a new concurrent (Constraint) logic programming language based on partially ordered event structures. A system is modeled as: (a) a set of concurrent processes, which are Prolog programs extended with event goals declaring program points of interest, and (b) a Constraint Store which imposes restrictions on the event goals execution order. The Constraint Store acts as a coordination entity which on the one hand encapsulates the system synchronization requirements, and on the other hand, provides a declarative specification of the system concurrency issues. This produces a powerful formalism which at the same time, overcome the deficiencies of traditional concurrent logic programming languages and preserve the benefits of declarative programming.

  • ICECCS - Concurrent programming made easy
    Proceedings Sixth IEEE International Conference on Engineering of Complex Computer Systems. ICECCS 2000, 1
    Co-Authors: Rafael Ramirez, Andrew E. Santosa, Roland H. C. Yap
    Abstract:

    The task of programming concurrent systems is substantially more difficult than the task of programming sequential systems with respect to both correctness and efficiency. In this paper we describe a Constraint-based methodology for writing concurrent applications. A system is modeled as: (a) a set of processes containing a sequence of "markers" denoting the processes points of interest; and (b) a Constraint Store. Process synchronization is specified by incrementally adding Constraints on the markers execution order into the Constraint Store. The Constraint Store contains a declarative specification based on a temporal Constraint logic program. The Store, thus, acts as a coordination entity which on the one hand encapsulates the system synchronization requirements, and on the other hand, provides a declarative specification of the system concurrency issues. This provide great advantages in writing concurrent programs and manipulating them while preserving correctness.

  • IPDPS - A methodology for concurrent and distributed Java applications
    Proceedings International Parallel and Distributed Processing Symposium, 1
    Co-Authors: Rafael Ramirez, Andrew E. Santosa
    Abstract:

    In this paper we describe a Constraint-based methodology for writing concurrent and distributed Java applications. A system is modeled as: (a) a set of Java threads containing a sequence of markers, denoting the threads points of interest; and (b) a Constraint Store. The key advantages are that there is a clear separation of the concurrency aspects of the system's threads from the threads functionality, and threads are coordinated by a formal Constraint-based specification. The treatment of the concurrency issues as orthogonal to the rest of the code allows programmers to independently develop one component from the other, and the declarative nature of the coordination mechanism provides a natural framework for formal verification, synthesis and transformation of concurrent Java programs.

Luca Bortolussi - One of the best experts on this subject based on the ideXlab platform.

  • WCB@ICLP - Perspectives on Constraints, Process Algebras, and Hybrid Systems.
    2010
    Co-Authors: Luca Bortolussi, Alberto Policriti
    Abstract:

    Building on a technique for associating Hybrid Systems (HS) to stochastic programs written in a stochastic extension of Concurrent Constraint Programming (sCCP), we will discuss several aspects of performing such association. In particular, as we proved an sCCP program can be mapped in a HS varying in a lattice at a level depending on the amount of actions to be simulated continuously, we will discuss what are the problems involved in a semi-automatic choice of such level. Decidability, semantic, and efficiency issues will be taken into account, with special emphasis on their links with biological applications. We will also discuss about the role of Constraints and of the Constraint Store in this construction.

  • stochastic concurrent Constraint programming
    Electronic Notes in Theoretical Computer Science, 2006
    Co-Authors: Luca Bortolussi
    Abstract:

    Abstract We present a stochastic version of Concurrent Constraint Programming (CCP), where we associate a rate to each basic instruction that interacts with the Constraint Store. We give an operational semantic that can be provided either with a discrete or a continuous model of time. The notion of observables is discussed, both for the discrete and the continuous version, and a connection between the two is given. Finally, a possible application for modeling biological networks is presented.

  • a distributed and probabilistic concurrent Constraint programming language
    International Conference on Logic Programming, 2005
    Co-Authors: Luca Bortolussi, Herbert Wiklicky
    Abstract:

    We present a version of the CCP paradigm, which is both distributed and probabilistic. We consider networks with a fixed number of nodes, each of them possessing a local and independent Constraint Store. While locally the computations evolve asynchronously, following the usual rules of (probabilistic) CCP, the communications among different nodes are synchronous. There are channels, and through them different objects can be exchanged: Constraints, agents and channel themselves. In addition, all this activities are embedded in a probabilistic scheme based on a discrete model of time, both locally and globally. Finally we enhance the language with the capability of performing an automatic remote synchronization of variables belonging to different Constraint Stores.

  • ICLP - A distributed and probabilistic concurrent Constraint programming language
    Logic Programming, 2005
    Co-Authors: Luca Bortolussi, Herbert Wiklicky
    Abstract:

    We present a version of the CCP paradigm, which is both distributed and probabilistic. We consider networks with a fixed number of nodes, each of them possessing a local and independent Constraint Store. While locally the computations evolve asynchronously, following the usual rules of (probabilistic) CCP, the communications among different nodes are synchronous. There are channels, and through them different objects can be exchanged: Constraints, agents and channel themselves. In addition, all this activities are embedded in a probabilistic scheme based on a discrete model of time, both locally and globally. Finally we enhance the language with the capability of performing an automatic remote synchronization of variables belonging to different Constraint Stores.

  • Perspectives on Constraints, Process Algebras, and Hybrid Systems
    1
    Co-Authors: Luca Bortolussi, Alberto Policriti
    Abstract:

    Building on a technique for associating Hybrid Systems (HS) to stochastic programs written in a stochastic extension of Concurrent Constraint Programming (sCCP), we will discuss several aspects of performing such association. In particular, as we proved an sCCP program can be mapped in a HS varying in a lattice at a level depending on the amount of actions to be simulated continuously, we will discuss what are the problems involved in a semi-automatic choice of such level. Decidability, semantic, and efficiency issues will be taken into account, with special emphasis on their links with biological applications. We will also discuss about the role of Constraints and of the Constraint Store is this construction.