Overriding subsuming rules

International audienceThis paper is concerned with intelligent agents that are able to perform nonmonotonic reasoning, not only with, but also about general rules with exceptions. More precisely, the focus is on enriching a knowledge base Γ with a general rule that is subsumed by another rule already there. Such a problem is important because evolving knowledge needs not follow logic as it is well-known from e.g. the belief revision paradigm. However, belief revision is mainly concerned with the case that the extra information logically conflicts with Γ. Otherwise, the extra knowledge is simply doomed to extend Γ with no change altogether. The problem here is different and may require a change in Γ even though no inconsistency arises. The idea is that when a rule is to be added, it might need to override any rule that subsumes it: preemption must take place. A formalism dedicated to reasoning with and about rules with exceptions is introduced. An approach to dealing with preemption over such rules is then developed

Logic-based Fusion of Legal Knowledge

International audienceIn this paper, we address several issues that are often overlooked in the fusion of various knowledge components when this knowledge is expressed in full standard logic. It is shown that not solving these issues can lead to inadequate inferences. As a case study, we consider the legal domain, which has been an application target for knowledge engineering for decades. Real- life examples based on the confrontation of two different legal systems about a same international agreement are investigated

Handling Incoming Beliefs

International audienceMost logic-based approaches to knowledge and belief change in artificial intelligence assume that when a new piece of information comes up, it should be merely added to the current beliefs or knowledge when this does not lead to inconsistency. This paper addresses situations where this assumption does not hold. The focus is on the construction of Boolean standard-logic knowledge and belief bases in this context. We propose an approach to handle incoming beliefs that can require some formulas reconstruction or a form of preemption to be performed

Méthodes permettant la prédominance de connaissances subsumées

Cette thèse s inscrit dans le domaine de l Intelligence Artificielle symbolique. Elle y traite d une question fondamentale liée à la représentation des connaissances et des raisonnements à base de logique. Plus précisément, elle s intéresse au problème pouvant se produire lors de l insertion dans un ensemble de connaissances d une information qui peut déjà en être déduite. Comment faire en sorte que cette nouvelle information vienne préempter les informations qui permettent son inférence ? Supposons par exemple qu un ensemble de prémisses contienne l information Si l interrupteur est enclenché alors la pièce est éclairée . Il est naturel d espérer que l ajout d une règle additionnelle, en un sens plus précise que la première, et qui exprime que Si l interrupteur est enclenché et si l ampoule n est pas cassée alors la pièce est éclairée , puisse venir la préempter. En effet, il ne doit plus être suffisant de savoir que L interrupteur soit enclenché pour en conclure que La pièce est éclairée : il faut aussi que L ampoule ne soit pas cassée . Remarquons que la seconde règle est consistante avec la première et que les cadres de logiques non monotones et de révision de croyances ou de mise à jour ne traitent pas a priori de ce problème. Nous adressons d abord cette question dans le cadre de la logique classique et ensuite dans un cadre plus général de représentation à base de logiques non monotones, et particulièrement de celles permettant la représentation de règles avec exceptions reposant sur des tests de consistance.This thesis is in line with the symbolic Artificial Intelligence domain. It deals with a fondamental issue of the logic-based knowledge and reasoning representation. Most particulary, this thesis is interested in the issue occurring when a piece of information is added to a knowledge set which already entails it. How to make sure that this new piece of information prevails the ones that allow its inference? Suppose for instance that a premisses set contains the piece of information If the switch is on then the room is lighted . It is natural to expect that adding an additional rule, in a way more precise than the first one, and which assert that If the switch is on and if the lamp bulb is not broken then the room is lighted , could prevail it. Indeed, it will not be sufficient to know that The switch is on to conclude that The room is lighted : it is now necessary that The lamp bulb is not broken . Let us note that the second rule is consistent with the first one and that the non monotonic logics and beliefs revision or update frameworks do not handle this issue in principle. First of all, we adress this issue in the classical logic framework, and secondly in a most general framework of non monotonic logic based representation, and particulary the ones that allow the representation of rules with exceptions subject of consistency test.ARRAS-Bib.electronique (620419901) / SudocSudocFranceF

Overriding Subsuming Rules

International audienc

Overriding Subsuming Rules

International audienc