Who may say what? Thoughts about objectivity, group ability and permission in dynamic epistemic logic

De nombreuses situations font intervenir la notion de communication ainsi que des restrictions sur cette communication. C'est le cas lorsque l'on pense à des informations militaires, des communications médicales, des normes morales, des jeux, etc. Dans certaines des ces situations, il se peut qu'existent des structures pour penser et organiser le droit de communiquer. Dans l'armée par exemple une telle structure est assez simple et facile à comprendre: plus on est haut-placé dans la hiérarchie militaire, plus on a le droit de savoir et moins on a l'autorisation de dire. Le champ médical est un exemple où des restrictions plus subtiles empêchent un patron d'avoir accès à des données médicales d'un de ses travailleurs, alors qu'un docteur devrait pouvoir y avoir accès. Souvent, ces structures sont présentées sous la forme d'un ensemble de règles informelles, ensemble qui peut être incomplet et même contradictoire, laissant la justice décider ce qu'il convient de faire en cas de conflits. L'objectif de ce mémoire est d'apporter quelques éléments, dans le champ de la logique, pour une meilleure compréhension de la notion de `droit de savoir', éléments qui pourraient nous aider à comprendre et répondre aux problèmes pour lesquels cette notion rentre en jeu. On concentre notre réflexion sur la partie informative de la communication, ce qui amène notre sujet central à la notion de `droit de donner une information'.Many situations involve communication and some kind of restrictions on this communication. This is the case when we think about military information, medical communication, moral norms, games, etc. In some situations, we may have structures to think about and organize the right to communicate in such situations. In the army, for example, such a structure is quite simple and easy to understand: the higher you are in the hierarchy, the more you may know and the less you are allowed to say. Indeed, a general can know any secret information but have no right to reveal it to his soldiers, while a soldier can give any information he wants (and may have to give the information he has) without having the right to access most of the information. As another example, in the medical field, more subtle restrictions prevent a boss from getting one of his workers' medical information, while a doctor may have access to it. Often such structures are presented as an informal and incomplete set of rules, that may be contradictory (and let the justice decide what should be done in case of conflict). But we have no general framework to analyze such situations. The aim of this dissertation is to make some progress, in the field of logic, in the understanding of the notion of `right to say', progress that may help us understand and answer problems that involve such a notion. We focus on the informative part of communication (and not on its form) leading our topic to the notion of `right to give a piece of information'

Tableaux for non-normal public announcement logic

International audienceThis paper presents a tableau calculus for two semantic interpretations of public announcements over monotone neighbourhood models: the intersection and the subset semantics, developed by Ma and Sano. We show that, without employing reduction axioms, both calculi are sound and complete with respect to their corresponding semantic interpretations and, moreover, we establish that the satisfiability problem of this public announcement extensions is NP-complete in both cases. The tableau calculi has been implemented in Lotrecscheme

Generalized DEL-sequents

Abstract. Let us consider a sequence of formulas providing partial information about an initial situation, about a set of events occurring sequentially in this situation, and about the resulting situation after the occurrence of each event. From this whole sequence, we want to infer more information, either about the initial situation, or about one of the events, or about the resulting situation after one of the events. Within the framework of Dynamic Epistemic Logic (DEL), we show that these different kinds of problems are all reducible to the problem of inferring what holds in the final situation after the occurrence of all the events. We then provide a tableau method deciding whether this kind of inference is valid. We implement it in LotrecScheme and show that these inference problems are NEXPTIME-complete. We extend our results to the cases where the accessibility relation is serial and reflexive and illustrate them with the coordinated attack problem.

Tableau method and NEXPTIME-Completeness of DEL-Sequents

International audienceDynamic Epistemic Logic (DEL) deals with the representation of situations in a multi-agent and dynamic setting. It can express in a uniform way statements about: (i) what is true about an initial situation (ii) what is true about an event occurring in this situation (iii) what is true about the resulting situation after the event has occurred. After proving that what we can infer about (ii) given (i) and (iii) and what we can infer about (i) given (ii) and (iii) are both reducible to what we can infer about (iii) given (i) and (ii), we provide a tableau method deciding whether such an inference is valid. We implement it in LOTRECscheme and show that this decision problem is NEXPTIME-complete. This contributes to the proof theory and the study of the computational complexity of DEL which have rather been neglected so far

Electronic Notes in Theoretical Computer Science

Abstract Dynamic Epistemic Logic (DEL) deals with the representation of situations in a multi-agent and dynamic setting. It can express in a uniform way statements about: (i) what is true about an initial situation (ii) what is true about an event occurring in this situation (iii) what is true about the resulting situation after the event has occurred. After proving that what we can infer about (ii) given (i) and (iii) and what we can infer about (i) given (ii) and (iii) are both reducible to what we can infer about (iii) given (i) and (ii), we provide a tableau method deciding whether such an inference is valid. We implement it in LOTRECscheme and show that this decision problem is NEXPTIME-complete. This contributes to the proof theory and the study of the computational complexity of DEL which have rather been neglected so far. Keywords: Dynamic epistemic logic, tableau method, computational complexity 1 This paper corrects the paper published under the same name and the same authors in the proceedings of M4M 2011. The rule ⊥ of the tableau method was missing. 2 We thank Sophie Pinchinat for helpful discussions and three reviewers for comments.

Electronic Notes in Theoretical Computer Science

Abstract Dynamic Epistemic Logic (DEL) deals with the representation of situations in a multi-agent and dynamic setting. It can express in a uniform way statements about: (i) what is true about an initial situation (ii) what is true about an event occurring in this situation (iii) what is true about the resulting situation after the event has occurred. After proving that what we can infer about (ii) given (i) and (iii) and what we can infer about (i) given (ii) and (iii) are both reducible to what we can infer about (iii) given (i) and (ii), we provide a tableau method deciding whether such an inference is valid. We implement it in LOTRECscheme and show that this decision problem is NEXPTIME-complete. This contributes to the proof theory and the study of the computational complexity of DEL which have rather been neglected so far. Keywords: Dynamic epistemic logic, tableau method, computational complexity 1 This paper corrects the paper published under the same name and with the same authors in the proceedings of M4M 2011. The rule ⊥ ′′ of the tableau method was missing. 2 We thank Sophie Pinchinat for helpful discussions and three reviewers for comments