Towards Consistency-Based Reliability Assessment

International audienceMOTIVATION : Merging information provided by several sources is an important issue and merging techniques have been extensively studied. When the reliability of the sources is not known, one can apply merging techniques such as majority or arbitration merging or distancebasedmerging for solving conflicts between information. At the opposite, if the reliability of the sources is known, either represented in a quantitative or in a qualitative way, then it can be used to manage contradictions: information provided by a source is generally weakened or ignored if it contradicts information provided by a more reliable source [1, 4, 6]. Assessing the reliability of information sources is thus crucial. The present paper addresses this key question. We adopt a qualitative point of view for reliability representation by assuming that the relative reliability of information sources is represented by a total preorder. This works considers that we have no information about the sources and in particular, we do not know if they are correct (i.e they provide true information) or not. We focus on a preliminary stage of observation and assessment of sources. We claim that during that stage the key issue is a consistency analysis of information provided by sources, whether it is the consistency of single reports or consistency w.r.t trusted knowledge or the consistency of different reports together. We adopt an axiomatic approach: first we give some postulates which characterize what this reliability preorder should be, then we define a generic operator for building this preorder in agreement with the postulates

Consistency-Based Reliability Assessment

International audienceThis paper addresses the question of assessing the relative reliability of unknown information sources. We propose to consider a phase during which the consistency of information they report is analysed, whether it is the consistency of each single report, or the consistency of a report w.r.t. some trusted knowledge or the consistency of different reports together. We adopt an axiomatic approach by first giving postulates which characterize how the resulting reliability preorder should be; then we define a family of operators for building this preorder and demonstrate that it satisfies the proposed postulates

Consistency-Based Reliability Assessment

This paper addresses the question of assessing the relative reliability of unknown information sources. We propose to consider a phase during which the consistency of information they report is analysed, whether it is the consistency of each single report, or the consistency of a report w.r.t. some trusted knowledge or the consistency of different reports together. We adopt an axiomatic approach by first giving postulates which characterize how the resulting reliability preorder should be; then we define a family of operators for building this preorder and demonstrate that it satisfies the proposed postulates

Utiliser les mesures d'inconsistance pour estimer la fiabilité

International audienceAny decision taken by an agent requires some knowledge of its environment. Communication with other agents is a key issue for assessing the overall quality of its own knowledge. This assessment is a challenge itself as the agent may receive information from unknown agents. The aim of this paper is to propose a framework for assessing the reliability of unknown agents based on communication. We assume that information is represented through logical statements and logical inconsistency is the underlying notion of reliability assessment. In our context, assessing consists of ranking the agents and representing reliability through a total preorder.The overall communication set is first evaluated with the help of inconsistency measures. Next, the measures are used for assessing the contribution of each agent to the overall inconsistency of the communication set. After stating the postulates specifying the expected properties of the reliability preorder, we show through a representation theorem how these postulates and the contribution of the agent are interwoven. We also detail how the properties of the inconsistency measures influence the properties of the contribution assessment. Finally we describe how to aggregate different reliability preorders, each of them may be based on different inconsistency measures.Cet article présente une méthode pour calculer la fiabilité relative de sources d'informations. En se basant sur les degrés d'inconsistance des informations rapportées par les agents, on définit la contribution de chaque agent dans l'inconsistance. Après avoir listé des postulats spécifiant les propriétés attendues d'un pré-ordre de fiabilité, on établit un théorème de représentation qui relie les postulats à cette fonction de contribution. Enfin, on décrit comment agréger différents pré-ordres de fiabilité

From Signed Information to Belief in Multi-Agent Systems (Third International Workshop on Languages, Methodologies and Development Tools for Multi-Agent Systems (LADS-2010), Lyon, France, 31/08/10-02/09/10)

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Mise à jour de pré-ordres basée sur la consistance pour estimer la fiabilité relative de sources d'informations

National audienceCertaines méthodes de fusion d'informations supposent que les sources d'informations sont ordonnées en fonction de leur fiabilité relative et donnent plus d'importance aux informations provenant de sources plus fiables.Dans cet article, nous nous plaçons en amont de ces processus de fusion et nous nous intéressons à la phase d'estimation de la fiabilité relative des sources, modélisée ici par un pré-ordre total. Nous voyons cette phase comme une phase de mise à jour qui à partir d'un pré-ordre initial représentant l'a priori que l'utilisateur peut avoir sur la fiabilité relative des sources, construit un nouveau pré-ordre en utilisant uniquement les informations émises par les sources durant cette phase. La propriété majeure qui est exploitée est la consistance de ces informations émises vis à vis notamment d'informations considérées comme certaines. Les contributions de cet article sont d'une part, un ensemble de postulats qui caractérisent ces opérateurs de mise-à-jour, et d'autre part des opérateurs de mise-à-jour particuliers dont on discute la conformité vis à vis de ces postulats

Relevant minimal change in belief update

The notion of relevance was introduced by Parikh in the belief revision field for handling minimal change. It prevents the loss of beliefs that do not have connections with the epistemic input. But, the problem of minimal change and relevance is still an open issue in belief update. In this paper, a new framework for handling minimal change and relevance in the context of belief update is introduced. This framework goes beyond relevance in Parikh’s sense and enforces minimal change by first rewriting the Katzuno-Mendelzon postulates for belief update and second by introducing a new relevance postulate. We show that relevant minimal change can be characterized by setting agent’s preferences on beliefs where preferences are indexed by subsets of models of the belief set. Each subset represents a prime implicant of the belief set and thus stresses the key propositional symbols for representing the belief set