Nicolas Schwind

Merging Qualitative Constraints Networks Using Propositional Logic

In this paper we address the problem of merging qualitative constraints networks (QCNs ). We propose a rational merging procedure for QCNs . It is based on translations of QCNs into propositional formulas, and take advantage of propositional merging operators.

Characterization Theorems for Revision of Logic Programs

We address the problem of belief revision of logic programs, i.e., how to incorporate to a logic program

A syntactical approach to qualitative constraint networks merging

\mathcal{P}

Merging Qualitative Constraint Networks in a Piecewise Fashion

a new logic program

Characterization of Logic Program Revision as an Extension of Propositional Revision

\mathcal{Q}

Formalization of resilience for constraint-based dynamic systems

. Based on the structure of SE interpretations, Delgrande et al. [5] adapted the AGM postulates to identify the rational behavior of generalized logic program GLP revision operators and introduced some specific operators. In this paper, a constructive characterization of all rational GLP revision operators is given in terms of an ordering among propositional interpretations with some further conditions specific to SE interpretations. It provides an intuitive, complete procedure for the construction of all rational GLP revision operators and makes easier the comprehension of their semantic properties. In particular, we show that every rational GLP revision operator is derived from a propositional revision operator satisfying the original AGM postulates. Taking advantage of our characterization, we embed the GLP revision operators into structures of Boolean lattices, that allow us to bring to light some potential weaknesses in the adapted AGM postulates. To illustrate our claim, we introduce and characterize axiomatically two specific classes of rational GLP revision operators which arguably have a drastic behavior.

Utilitarian and Egalitarian Solutions for Multi-objective Constraint Optimization

We address the problem of merging qualitative constraint networks (QCNs) representing agents local preferences or beliefs on the relative position of spatial or temporal entities. Two classes of merging operators which, given a set of input QCNs defined on the same qualitative formalism, return a set of qualitative configurations representing a global view of these QCNs, are pointed out. These operators are based on local distances and aggregation functions. In contrast to QCN merging operators recently proposed in the literature, they take account for each constraint from the input QCNs within the merging process. Doing so, inconsistent QCNs do not need to be discarded at start, hence agents reporting locally consistent, yet globally inconsistent pieces of information (due to limited rationality) can be taken into consideration.

Lost in translation: Language independence in propositional logic - application to belief change

We address the problem of merging qualitative constraints networks (QCNs). We point out a merging algorithm which computes a consistent QCN representing a global view of the input set of (possibly conflicting) QCNs. This algorithm is generic in the sense that it does not depend on a specific qualitative formalism. The efficiency of our method comes from the fact that it merges locally the constraints of the input QCNs bearing on the same pairs of variables. We define several constraint merging operators in a way to ensure that the induced QCNs merging operator satisfies some expected properties from a logical standpoint.

Merging qualitative constraint networks defined on different qualitative formalisms

We address the problem of belief revision of logic programs, i.e., how to incorporate to a logic program P a new logic program Q. Based on the structure of SE interpretations, Delgrande et al. adapted the well-known AGM framework to logic program (LP) revision. They identified the rational behavior of LP revision and introduced some specific operators. In this paper, a constructive characterization of all rational LP revision operators is given in terms of orderings over propositional interpretations with some further conditions specific to SE interpretations. It provides an intuitive, complete procedure for the construction of all rational LP revision operators and makes easier the comprehension of their semantic and computational properties. We give a particular consideration to logic programs of very general form, i.e., the generalized logic programs (GLPs). We show that every rational GLP revision operator is derived from a propositional revision operator satisfying the original AGM postulates. Interestingly, the further conditions specific to GLP revision are independent from the propositional revision operator on which a GLP revision operator is based. Taking advantage of our characterization result, we embed the GLP revision operators into structures of Boolean lattices, that allow us to bring to light some potential weaknesses in the adapted AGM postulates. To illustrate our claim, we introduce and characterize axiomatically two specific classes of (rational) GLP revision operators which arguably have a drastic behavior. We additionally consider two more restricted forms of logic programs, i.e., the disjunctive logic programs (DLPs) and the normal logic programs (NLPs) and adapt our characterization result to DLP and NLP revision operators.

Probabilistic Resilience in Hidden Markov Models

Many researchers in different fields are interested in building resilient systems that can absorb shocks and recover from damages caused by unexpected large-scale events. Existing approaches mainly focus on the evaluation of the resilience of systems from a qualitative point of view, or pay particular attention to some domain-dependent aspects of the resilience. In this paper, we introduce a very general, abstract computational model rich enough to represent a large class of constraint-based dynamic systems. Taking our inspiration from the literature, we propose a simple parameterized property which captures the main features of resilience independently from a particular application domain, and we show how to assess the resilience of a constraint-based dynamic system through this new resilience property.