A Neutral Temporal Deontic STIT Logic

In this work we answer a long standing request for temporal embeddings of deontic STIT logics by introducing the multi-agent STIT logic TDS . The logic is based upon atemporal utilitarian STIT logic. Yet, the logic presented here will be neutral: instead of committing ourselves to utilitarian theories, we prove the logic TDS sound and complete with respect to relational frames not employing any utilitarian function. We demonstrate how these neutral frames can be transformed into utilitarian temporal frames, while preserving validity. Last, we discuss problems that arise from employing binary utility functions in a temporal setting

Cut-free Calculi and Relational Semantics for Temporal STIT Logics

We present cut-free labelled sequent calculi for a central formalism in logics of agency: STIT logics with temporal operators. These include sequent systems for Ldm , Tstit and Xstit. All calculi presented possess essential structural properties such as contraction- and cut-admissibility. The labelled calculi G3Ldm and G3Tstit are shown sound and complete relative to irreflexive temporal frames. Additionally, we extend current results by showing that also Xstit can be characterized through relational frames, omitting the use of BT+AC frames

Knowledge and Blameworthiness

Blameworthiness of an agent or a coalition of agents is often defined in terms of the principle of alternative possibilities: for the coalition to be responsible for an outcome, the outcome must take place and the coalition should have had a strategy to prevent it. In this article we argue that in the settings with imperfect information, not only should the coalition have had a strategy, but it also should have known that it had a strategy, and it should have known what the strategy was. The main technical result of the article is a sound and complete bimodal logic that describes the interplay between knowledge and blameworthiness in strategic games with imperfect information

A logical analysis of responsibility attribution : emotions, individuals and collectives

International audienceThe aim of this article is to provide a logical analysis of the concept of responsibility attribution; that is, how agents ascribe responsibility about the consequences of actions, either to themselves or to other agents. The article is divided in two parts. The first part investigates the importance of the concept of responsibility attribution for emotion theory in general and, in particular, for the theory of attribution emotions such as guilt, pride, moral approval and moral disapproval. The second part explores the collective dimension of responsibility attribution and attribution emotions, namely the concepts of collective responsibility and collective guilt. The proposed analysis is based on an extension of the logic STIT (the logic of ‘Seeing To It That’) with three different types of knowledge and common knowledge modal operators depending on the time of choice: before one’s choice, after one’s choice but before knowing the choices of other agents, and after the choices of all agents have become public. Decidability of the satisfiability problem of the logic is studied in the article

Deontic Epistemic stit Logic Distinguishing Modes of `Mens Rea\u27

Most juridical systems contain the principle that an act is only unlaw- ful if the agent conducting the act has a `guilty mind\u27 (`mens rea\u27). Dif- ferent law systems distinguish different modes of mens rea. For instance, American law distinguishes between `knowingly\u27 performing a criminal act, `recklessness\u27, `strict liability\u27, etc. I will show we can formalize several of these categories. The formalism I use is a complete stit-logic featuring operators for stit-actions taking effect in `next\u27 states, S5-knowledge op- erators and SDL-type obligation operators. The different modes of `mens rea\u27 correspond to the violation conditions of different types of obligation definable in the logic

Grounding power on actions and mental attitudes

International audienceThe main objective of this work is to develop a logic called IAL (Intentional Agency Logic) in which we can reason about mental states of agents, action occurrences, and agentive and group powers. IAL will be exploited for a formal analysis of different forms of power such as an agent i's power of achieving a certain result and an agent i's power over another agent j (alias social power)

Temporal STIT logic and its application to normative reasoning

International audienceI present a variant of STIT with time, called T-STIT (Temporal STIT), interpreted in standard Kripke semantics. On the syntactic level, T-STIT is nothing but the extension of atemporal individual STIT by: (i) the future tense and past tense operators, and (ii) the operator of group agency for the grand coalition (the coalition of all agents). A sound and complete axiomatisation for T-STIT is given. Moreover, it is shown that T-STIT supports reasoning about interesting normative concepts such as the concepts of achievement obligation and commitment

Seeing, Knowing, doing : case studies in modal logic

Dans le domaine des jeux vidéos par exemple, surtout des jeux de rôles, les personnages virtuels perçoivent un environnement, en tirent des connaissances puis effectuent des actions selon leur besoin. De même en robotique, un robot perçoit son environnement à l'aide de capteurs/caméras, établit une base de connaissances et effectuent des mouvements etc. La description des comportements de ces agents virtuels et leurs raisonnements peut s'effectuer à l'aide d'un langage logique. Dans cette thèse, on se propose de modéliser les trois aspects "voir", "savoir" et "faire" et leurs interactions à l'aide de la logique modale. Dans une première partie, on modélise des agents dans un espace géométrique puis on définit une relation épistémique qui tient compte des positions et du regard des agents. Dans une seconde partie, on revisite la logique des actions "STIT" (see-to-it-that ou "faire en sorte que") qui permet de faire la différence entre les principes "de re" et "de dicto", contrairement à d'autres logiques modales des actions. Dans une troisième partie, on s'intéresse à modéliser quelques aspects de la théorie des jeux dans une variante de la logique "STIT" ainsi que des émotions contre-factuelles comme le regret. Tout au long de cette thèse, on s'efforcera de s'intéresser aux aspects logiques comme les complétudes des axiomatisations et la complexité du problème de satisfiabilité d'une formule logique. L'intégration des trois concepts "voir", "savoir" et "faire" dans une et une seule logique est évoquée en conclusion et reste une question ouverte.Agents are entities who perceive their environment and who perform actions. For instance in role playing video games, ennemies are agents who perceive some part of the virtual world and who can attack or launch a sortilege. Another example may concern robot assistance for disabled people: the robot perceives obstacles of the world and can alert humans or help them. Here, we try to give formal tools to model knowledge reasoning about the perception of their environment and about actions based, on modal logic. First, we give combine the standard epistemic modal logic with perception constructions of the form (agent a sees agent b). We give a semantics in terms of position and orientation of the agents in the space that can be a line (Lineland) or a plane (Flatland). Concerning Lineland, we provide a complete axiomatization and an optimal procedure for model-checking and satisfiability problem. Concerning Flatland, we show that both model-checking and satisfiability problem are decidable but the exact complexities and the axiomatization remain open problems. Thus, the logics of Lineland and Flatland are completely a new approach: their syntax is epistemic but their semantics concern spatial reasoning. Secondly, we study on the logic of agency ``see-to-it-that'' STIT made up of construction of the form [J]A standing for ``the coalition of agents J sees to it that A''. Our interest is motivated: STIT is strictly more expressive that standard modal logic for agency like Coalition Logic CL or Alternating-time Temporal Logic ATL. In CL or ATL the ``de re'' and ``de dicto'' problem is quite difficult and technical whereas if we combine STIT-operators with epistemic operators, we can solve it in a natural way. However this strong expressivity has a prize: the general version of STIT is undecidable. That is why we focus on some syntactic fragments of STIT: either we restrict the allowed coalitions J in constructions [J]A or we restrict the nesting of modal STIT-operators. We provide axiomatizations and complexity results. Finally, we give flavour to epistemic modal logic by adding STIT-operators. The logic STIT is suitable to express counterfactual statements like ``agent a could have choosen an action such that A have been true''. Thus we show how to model counterfactual emotions like regret, rejoicing, disappointment and elation in this framework. We also model epistemic games by adapting the logic STIT by giving explicitely names of actions in the language. In this framework, we can model the notion of rational agents but other kind of behaviour like altruism etc., Nash equilibrium and iterated deletion of strictly dominated strategies