Camilo Rueda

Models and emerging trends of concurrent constraint programming

Concurrent Constraint Programming (CCP) has been used over the last two decades as an elegant and expressive model for concurrent systems. It models systems of agents communicating by posting and querying partial information, represented as constraints over the variables of the system. This covers a vast variety of systems as those arising in biological phenomena, reactive systems, net-centric computing and the advent of social networks and cloud computing. In this paper we survey the main applications, developments and current trends of CCP.

Integrating Constraints and Concurrent Objects in MusicalApplications: A Calculus and its Visual Language

We propose PiCO, a calculus integrating concurrent objects and constraints, as a base for music composition tools. In contrast with calculi such as NiehrenMueller:Free, milner.parrow.ea:calculus-mobile or TyCO vasconcelos:typed-concurrent, both constraints and objects are primitive notions in PiCO. In PiCO a base object model is extended with constraints by orthogonally adding the notion of constraint system found in the ρ-calculus OzCalculus. Concurrent processes make use of a constraint store to synchronize communications either via the ask and tell operations of the constraint model or the standard message-passing mechanism of the object model. A message delegation mechanism built into the calculus allows encoding of general forms of inheritance. This paper includes encodings in PiCO of the concepts of class and sub-class. These allow us to represent complex partially defined objects such as musical structures in a compact way. We illustrate the transparent interaction of constraints and objects by a musical example involving harmonic and temporal relations. The relationship between Cordial, a visual language for music composition applications, and its underlying model PiCO is described.

Matelas: a predicate calculus common formal definition for social networking

This paper presents Matelas, a B predicate calculus definition for social networking, modelling social-network content, privacy policies, social-networks friendship relations, and how these relations effect users’ policies. The work presented in this paper is part of an ongoing work that aims at using several formal methods tools and techniques to develop a full-fledged social-network service implementing stipulated policies. Although we employed Atelier B to write Matelas, plans are to port it to Event B and to use Rodin to implement the social-network application.

A Declarative Language for Dynamic Multimedia Interaction Systems

Universal Timed Concurrent Constraint Programming (utcc) is a declarative model for concurrency tied to logic. It aims at specifying mobile reactive systems, i.e., systems that continuously interact with the environment and may change their communication structure. In this paper we argue for utcc as a declarative model for dynamic multimedia interaction systems. Firstly, we show that the notion of constraints as partial information allows us to neatly define temporal relations between interactive agents or events. Secondly, we show that mobility in utcc allows for the specification of more flexible and expressive systems. Thirdly, by relying on the underlying temporal logic in utcc, we show how non-trivial temporal properties of the model can be verified. We give two compelling applications of our approach. We propose a model for dynamic interactive scores where interactive points can be defined to adapt the hierarchical structure of the score depending on the information inferred from the environment. We then broaden the interaction mechanisms available for the composer in previous (more static) models. We also model a music improvisation system based on the factor oracle that scales up to situations involving several players, learners and improvisers.

An Overview of FORCES: An INRIA Project on Declarative Formalisms for Emergent Systems

The FORCES project aims at providing robust and declarative formalisms for analyzing systems in the emerging areas of Security Protocols, Biological Systems and Multimedia Semantic Interaction . This short paper describes FORCESs motivations, results and future research directions.

Code generation for Event-B

Event-B is a modelling language and a formal methods approach for correct construction of software. This paper presents our work on code generation for Event-B, including the definition of a syntactic translation from Event-B to JML-annotated Java programs, the implementation of the translation as the EventB2Java tool, and two case studies on the use of EventB2Java. The first case study is on implementing an Android application with the aid of the EventB2Java tool, and the second on testing an Event-B specification of the Tokeneer security-critical system. Additionally, we have benchmarked our EventB2Java tool against two other Java code generators for Event-B.

An algebraic view of space/belief and extrusion/utterance for concurrency/epistemic logic

We enrich spatial constraint systems with operators to specify information and processes moving from a space to another. We shall refer to these news structures as spatial constraint systems with extrusion. We shall investigate the properties of this new family of constraint systems and illustrate their applications. From a computational point of view the new operators provide for process/information extrusion, a central concept in formalisms for mobile communication. From an epistemic point of view extrusion corresponds to a notion we shall call utterance; a piece of information that an agent communicates to others but that may be inconsistent with the agents beliefs. Utterances can then be used to express instances of epistemic notions, which are common place in social media, such as hoaxes or intentional lies. Spatial constraint systems with extrusion can be seen as complete Heyting algebras equipped with maps to account for spatial and epistemic specifications.

Non-determinism and Probabilities in Timed Concurrent Constraint Programming

A timed concurrent constraint process calculus with probabilistic and non-deterministic choices is proposed. We outline the rationale of an operational semantics for the calculus. The semantics ensures consistent interactions between both kinds of choices and is indispensable for the definition of logic-based verification capabilities over system specifications.

Translating B machines to JML specifications

In this work, we present a translation from B machines to JML specifications. Our work allows developers to use different formal methods techniques and tools at different software development phases. A developer can use Bs strong support for model verification during early stages of software development to produce a fully verified model of the application, and then transition to JML to simplify the task of producing a Java implementation and to take advantage of JML (semi-) automatic tools such as runtime assertion checkers. We have validated our implementation of the translation by applying it to a moderately complex B model of a social networking site, and then by executing the resulting JML specifications against a suite of test cases developed for a hand-translation of the B model. We have implemented the translation as the B2Jml tool, which has been integrated to the ABTools suite.

On validity in modelization of musical problems by CCP

We show how the ntcc calculus, a model of temporal concurrent constraint programming with the capability of modeling asynchronous and non-deterministic timed behavior, can be used for modeling real musical processes. In particular, we show how the expressiveness of ntcc allows to implement complex interactions among musical processes handling different kinds of partial information. The ntcc calculus integrates two dimensions of soft computing: a horizontal dimension dealing with partial information and a vertical one in which non determinism comes into play. This integration is an improvement over constraint satisfaction and concurrent constraint programming models, allowing a more natural representation of a variety of musical processes. We use the nondeterminism facility of ntcc to build weaker representations of musical processes that greatly simplifies the formal expression and analysis of its properties. We argue that this modeling strategy provides a “runnable specification” for music problems that eases the task of formally reasoning about them. We show how the linear temporal logic associated with ntcc gives a very expressive setting for formally proving the existence of interesting musical properties of a process. We give examples of musical specifications in ntcc and use the linear temporal logic for proving properties of a realistic musical problem.