Opinions and Beliefs as constraint system operators

Appears as Abstract Paper at the Technical Communications of the 31st International Conference on Logic Programming (ICLP 2015)International audienceThe growing presence of digital distributed systems in social life is exemplified by many particular instances, including opinion forums, social networks, dating sites and photo sharing portals. The increased usage in the last decade of these systems brings various risks and behaviors, inherent from the social interaction therein. An epistemic aspect is singled out as a common feature shared between these systems and the behaviors carried within them. Designing, constructing and verifying formalisms to represent information that is epistemic in nature can help develop a sound theory to analyze the scenarios mentioned before and at the same time bridge the concepts involved to a logical and mathematical domain. Regarding this, a specific concept of declarative and logic programming, that of a constraint system, deals with information represented by constraints (a constraint c could be a logical proposition partially describing a bigger system, e.g. temperature > 20). Constraint systems capable of incorporating the concept of spatiality such as user-spaces or message walls already exist (i.e. [c]_i , could read as " data/belief/constraint c belongs to agent i "). However, the movement of information between spaces is still not designed nor included in said constraint systems. Some process algebras do possess a concept of space mobility, notwithstanding, it is from an operational point of view, specifying only its behavior. Therefore it remains to mathematically define it along with all its properties. The proposed project intends to provide constraint systems with an algebraic operator that correspond to moving information in-between spaces as to mimic the mobility of data of distributed systems such as posting opinions/lies to other spaces or publicly disclosing data (i.e. ↑_i c reads as " extruding data/belief/constraint c from the space of agent i). Also, this extrusion operator should have a direct relationship with the spatiality operator, meaning that it should be modeled in constraint systems that also posses the concept of space (i.e. [c u ↑_i d] i = [c]_i u d reads " information d is extruded from the space of agent i " , it can be alternatively interpreted as agent i posting an opinion d). The authors developed a constraint system implementing the concepts of space and extrusion. The interaction between these conceptos account for mobility with no side effects , it is modeled as extrusion being the right inverse of space (i.e. [↑_i c]_i = c for any agent i). Additionally, given an already defined concept of space in a constraint system, the authors described different constructive ways of defining its extrusion and their mathematical properties. As a practical example, by means of a constraint system with space and extrusion, the authors gave semantic meaning to a logic with modalities of belief Bi and utterance Ui where BiUiφ ⇔ φ for any formula φ of the logic

An Algebraic View of Space/Belief and Extrusion/Utterance for Concurrency/Epistemic Logic

International audienceWe 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 pro-cess/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 agent's 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 specification

Deriving Inverse Operators for Modal Logic

International audienceSpatial constraint systems are algebraic structures from concurrent constraint programming to specify spatial and epistemic behavior in multi-agent systems. We shall use spatial constraint systems to give an abstract characterization of the notion of normality in modal logic and to derive right inverse/reverse operators for modal languages. In particular, we shall identify the weakest condition for the existence of right inverses and show that the abstract notion of normality corresponds to the preservation of finite suprema. We shall apply our results to existing modal languages such as the weakest normal modal logic, Hennessy-Milner logic, and linear-time temporal logic. We shall discuss our results in the context of modal concepts such as bisimilarity and inconsistency invariance

Belief, Knowledge, Lies and Other Utterances in an Algebra for Space and Extrusion

International audienceThe notion of constraint system (cs) is central to declarative formalisms from concurrency theory such as process calculi for concurrent constraint programming (ccp). Constraint systems are often represented as lattices: their elements, called constraints, represent partial information and their order corresponds to entailment. Recently a notion of n-agent spatial cs was introduced to represent information in concurrent constraint programs for spatially distributed multi-agent systems. From a computational point of view a spatial constraint system can be used to specify partial information holding in a given agent's space (local information). From an epistemic point of view a spatial cs can be used to specify information that a given agent considers true (beliefs). Spatial constraint systems, however, do not provide a mechanism for specifying the mobility of information/processes from one space to another. Information mobility is a fundamental aspect of concurrent systems. In this article we develop the theory of spatial constraint systems with operators to specify information and processes moving from a space to another. 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 I to a notion we shall call utterance; a piece of information that an agent communicate to others but that may be inconsistent with the agent's beliefs. Utterances can then be used to express instances of epistemic notions such as hoaxes or intentional lies which are common place in social media. Spatial constraint system can express the epistemic notion of belief by means of space functions that specify local information. We shall also show that spatial constraint can also express the epistemic notion of knowledge by means of a derived spatial operator that specifies global information

Procedural bridges-and-pillars support generation

International audienceAdditive manufacturing requires support structures to fabricate parts with overhangs. In this paper, we revisit a known support structure based on bridges-and-pillars. The support structures are made of vertical pillars supporting horizontal bridges. Their scaffolding structure makes them stable and reliable to print. However, the algorithm heuristic search does not scale well and is prone to produce contacts with the parts, leaving scars after removal. We propose a novel algorithm for this type of supports, focusing on avoiding unnecessary contacts with the part as much as possible. Our approach builds upon example-based model synthesis to enable early detection of collision-free passages as well as non-reachable regions

Interaction Multimédia avec NTCC

Musical phenomena are the most formally studied subset of the fine arts in our present time. From mathematical formalization to psychological analysis onto computer models are among the traces the scientific community have taken to explore music. One such formalism applied to model music is called NTCC , a constraint-based process algebra where operators are part of programs that may behave as musical agents.This work is aimed to provide a solid framework for interacting, constructing and deducting musical properties from an interpretation of a previously known score. The method is divided into two parts, an interactive construction of an NTCC process from executed musical events through the program ANTESCOFO and a model checking module for the output. A communication scheme between the two parts is implemented and documented, and finally an example with a musical piece is given along with analysis of its resultsLos fenómenos musicales son el subconjunto más estudiado de las bellas artes actualmente. Desde formalizaciones matemáticas, análisis psicológicos hasta modelos computacionales son algunas de los caminos que la comunidad científica ha tomado para explorar el campo musical. Uno de estos formalismos aplicados a modelar música se llama NTCC , un cálculo de procesos basada en restricciones donde los operadores son parte de programas que pueden comportarse como agentes musicales.Este trabajo tiene como objetivo proveer una herramienta de trabajo para la interacción, construcción y deducción de propiedades musicales de una interpretación con base en una partitura conocida a priori. El método está dividido en 2 partes, una construcción interactiva de un proceso NTCC de eventos musicales ejecutados a través del programa ANTESCOFO y un módulo model checker para la salida de la parte anterior. Un esquema de comunicación entre ambas partes fue implementado y documentado y, finalmente, un ejemplo con una pieza musical es mostrado en conjunto con un análisis de sus resultadosPhénomènes musicaux sont le sous-ensemble plus formellement étudié les beaux-arts dans notre époque actuelle. De la formalisation mathématique d'analyse psychologique sur des modèles informatiques sont parmi les traces de la communauté scientifique ont prises pour étudier la musique. Un tel formalisme appliqué à modéliser la musique est appelé NTCC, un processus algèbre base de contraintes où les opérateurs font partie de programmes qui peuvent se comporter comme des agents musicales.Ce travail vise à fournir un cadre solide pour l'interaction, la construction et la déduction des propriétés musicales d'une interprétation d'une partition déjà connu. La méthode est divisée en deux parties, une construction interactive d'un processus NTCC d'événements musicaux exécutés par l'entremise du programme Antescofo et un module de vérification de modèle pour la sortie. Un système de communication entre les deux parties est mis en œuvre et documenté, et enfin un exemple avec une pièce musicale est donnée ainsi que l'analyse de ses résultat

Opinions, Mensonges et Connaissance. Une Approche Algébrique à la Mobilité de l’Information et des Processus.

The notion of constraint system (cs) is central to declarative formalisms from concurrency theory such as process calculi for concurrent constraint programming (ccp). Constraint systems are often represented as lattices: their elements, called constraints, represent partial information and their order corresponds to entailment. Recently a notion of n-agent spatial cs was introduced to represent information in concurrent constraint programs for spatially distributed multi-agent systems. From a computational point of view a spatial constraint system can be used to specify partial information holding in a given agent’s space (local information). From an epistemic point of view a spatial cs can be used to specify information that a given agent considers true (beliefs). Spatial constraint systems, however, do not provide a mechanism for specifying the mobility of information/processes from one space to another. Information mobility is a fundamental aspect of concurrent systems.In this thesis we develop the theory of spatial constraint systems with operators to specify information and processes moving between spaces. We investigate the properties of this new family of cs 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 what we shall call utterance; information that an agent communicates to others but that may be inconsistent with the agent’s beliefs. Utterances can be used to express instances of epistemic notions such as hoaxes or intentional lies which are common place in social media.On the whole, constraint systems can express the epistemic notions of belief /utterance and knowledge by means of, respectively, a space/extrusion function pair that specifies local information and a derived spatial operator that specifies global information. We shall also show that, by using a specific kind of our constraint systems, we can also encode the notion of time as a sequence of instances.La notion de système de contraintes (cs – selon l'acronyme anglais) est un concept central aux formalismes de la théorie de la concurrence tels que les algèbres de processus pour la programmation concurrente par contraintes. Les systèmes de contraintes sont souvent représentés par des treillis : ses éléments, appelées contraintes, représentent des informations partiales tandis que l’ordre du treillis correspond à des implications. Récemment, une notion appelée “système de contraintes spatiales à n-agents” a été développée pour représenter l’information dans la programmation concurrente par contraintes où les systèmes sont multi-agents et spatialement distribués.D’un point de vue informatique, un système de contraintes spatiales peut être utilisé pour spécifier l’information partiale contenue dans l'espace d'un certain agent (information locale). D’un point de vue épistémique, un cs spatial peut être utilisé pour représenter l’information qui est considérée vrai pour un certain agent (croyance). Les systèmes de contraintes spatiales, néanmoins, ne fournissent pas de mécanismes pour la spécification de la mobilité de l’information ou des processus d'un espace à un autre. La mobilité de l’information est un aspect fondamental des systèmes concurrents.Dans cette thèse nous avons développé la théorie des systèmes de contraintes spatiales avec des opérateurs pour spécifier le déplacement des informations et processus entre les espaces. Nous étudions les propriétés de cette nouvelle famille de systèmes de contraintes et nous illustrons ses applications.Du point de vue calculatoire, ces nouveaux opérateurs nous apportent de l’extrusion d’informations et/ou des processus, qui est un concept central dans les formalismes pour la communication mobile. Du point de vue épistémique, l’extrusion correspond à une notion que nous avons appelé énonciation ; une information qu’un agent souhaite communiquer à d'autres mais qui peut être inconsistante avec les croyances de l’agent même. Des énonciations peuvent donc être utilisées pour exprimer des notions épistémiques tels que les canulars ou les mensonges qui sont fréquemment utilisés dans les réseaux sociaux.Globalement, les systèmes de contraintes peuvent exprimer des notions épistémiques comme la croyance/énonciation et la connaissance en utilisant respectivement une paire de fonctions espace/extrusion qui représentent l’information locale, et un opérateur spatial dérivé qui représente l’information globale. Par ailleurs, nous montrons qu’en utilisant un type précis de systèmes de contraintes nous pouvons aussi représenter la notion du temps comme une séquence d'instances

Declarative Framework for Semantical Interpretations of Structured Information — An Applicative Approach

International audienceWe study the applicability of declarative models to encode and describe structured information by means of semantics. Specifically, we introduce D-SPACES, an implementation of constraint systems with space and extrusion operators. Constraint systems are algebraic models that allow for a semantic language-like representation of information in systems where the concept of space is a primary structural feature. We mainly give this information an epistemic and temporal interpretation and consider various agents as entities acting upon it. D-SPACES is coded as a c++ library providing implementations of constraint systems, space functions and extrusion functions. The interfaces to access each implementation are minimal and thoroughly documented. D-SPACES also provides property-checking methods as well as an implementation of a specific type of constraint systems (a boolean algebra). This last implementation serves as an entry point for quick access and proof of concept when using these models. Finally, we show the applicability of this framework with two examples; a scenario in the form of a social network where users post their beliefs and utter their opinions, and a semantical interpretation of a logical language to express time behaviors and properties

D-SPACES: Implementing Declarative Semantics for Spatially Structured Information

International audienceWe introduce in this paper D-SPACES, an implementation of constraint systems with space and extrusion operators. Constraint systems are algebraic models that allow for a semantic language-like representation of information in systems where the concept of space is a primary structural feature. We give this information mainly an epistemic interpretation and consider various agents as entities acting upon it. D-SPACES is coded as a c++11 library providing implementations for constraint systems, space functions and extrusion functions. The interfaces to access each implementation are minimal and thoroughly documented. D-SPACES also provides property-checking methods as well as an implementation of a specific type of constraint systems (a boolean algebra). This last implementation serves as an entry point for quick access and proof of concept when using these models. Furthermore, we offer an illustrative example in the form of a small social network where users post their beliefs and utter their opinion

Characterizing Right Inverses for Spatial Constraint Systems with Applications to Modal Logic

International audienceSpatial constraint systems are algebraic structures from concurrent constraint programming to specify spatial and epistemic behavior in multi-agent systems. In this paper spatial constraint systems are used to give an abstract characterization of the notion of normality in modal logic and to derive right inverse/reverse operators for modal languages. In particular, a necessary and sufficient condition for the existence of right inverses is identified and the abstract notion of normality is shown to correspond to the preservation of finite suprema. Furthermore, a taxonomy of normal right inverses is provided, identifying the greatest normal right inverse as well as the complete family of minimal right inverses. These results are applied to existing modal languages such $ as the weakest normal modal logic, Hennessy-Milner logic, and linear-time temporal logic. Some implications of these results are also discussed in the context of modal concepts such as bisimilarity and inconsistency invariance