752 research outputs found
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
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 âSeeing To It Thatâ) with three different types of knowledge and common knowledge modal operators depending on the time of choice: before oneâs choice, after oneâs 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
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)
Recommended from our members
A Study of Agent Influence in Nested Agent Interactions
This work develops a theory of agent influence and applies it to a coached system of simple reactive agents. Our notion of influence is intended to describe agent ability which is contingent on the actions of other agents and we view such behaviours as being ânestedâ. An agent may have the ability to make A hold only if another agent has carried out a particular action. Our analysis of this is based on a combination of the observation of the effects of an agentâs actions in a bounded environment and observations on what may be changed in that environment and is intended to allow for a logical representation of nested behaviours. We build on this notion to develop a theory of influence which we offer as an extension of existing systems for representing agency and its effects.
The notion of an agent being able to âsee to itâ that something is brought about has been a useful device for reasoning about agent ability. These so-called STIT semantics have been developed by a number of researchers. Standard STIT semantics allow statements of the form [α stit: A] which says that agent a has the ability to see to it that A holds. Although based on the concept of agent action STIT semantics also allow for the representation of concepts involving what may be thought of as inaction. An agent deciding, for example, not to execute a particular action may be characterised as seeing to it that it does not see to it that A, [α stit: [α stit: -A]]. STIT encourages nesting and although this nesting extends across actions within an agent it does not extend easily across agents. So called other agent statements of the form [ÎČ stit: [α stit: A]] do not make sense in standard stit semantics because ÎČ seeing to it that α sees to it that A holds implies that ÎČ has some dominion over a which, in turn, compromises αâs agency. Although the statement makes no sense under standard STIT it does make sense in an intuitive way and Brian Chellas [31] notes that it would be:
â...bizarre to deny that an agent should be able to see to it that another agent sees to somethingâ
This is also mentioned in Belnap et al. [8, page 275]. Chellas is correct and there are numerous settings in which other agent STIT does make sense. These settings, which are captured in various readings of STIT, may bring a great deal of system level overhead. In a normative system, for example, ÎČ may have the option of imposing a sanction on α if α fails to bring about A and in this sense may be thought of as seeing to it that α sees to it that A holds. Similarly a deontic reading may place ÎČ in a position where it is able to place an obligation on α to bring about A. These readings allow for sensible interpretation of other agent STIT but the examples above require that agents have sufficient awareness of personal utility be able to manage sanctions or that they are able to reason about obligations. These readings offer nothing for simple agents with limited resources and abilities.
We offer another reading for the STIT element, one based on the concept of agent influence and one which carries minimal system level overhead. Because influence may be contingent on simultaneous or sequential behaviour by a number of agents it is extendible across agents and offers a means of addressing other agent statements. We extend the standard STIT semantics of Horty, Belnap and others with the introduction of âleads toâ and âmay lead toâ operators which allow us to move our analysis into a setting where observation provides evidence of influence. We then explore the manifestation of influence in a number of scenarios. After exploring how influence manifests itself we then offer a partial logical characterisation of the influence operators and discuss its relationship with standard STIT.
Building on these semantics and the partial logical characterisation we then explore the practical use of our theory of influence in an agent learning system. We describe experiments with a system specified by safety and liveness properties and having two broad classes of agents, actors and coaches. Actor agents will manipulate their environment and coaching agents will observe the actorâs behaviour and its effects using aggregated observations to generate new behaviours which are then seeded in the environment to modify actor behaviour.
We then offer a discussion and evaluation of our theory and its applications indicating where it may be further developed and applied
What an Agent Ought To Do
This paper reviewes Horty\u27s 2001 book `Agency and Deontic Logic\u27. We place Horty\u27s research I a broader context and discuss the relevancy for logics for multi-agent systems
Group Norms for Multi-Agent Organisations
W. W. Vasconcelos acknowledges the support of the Engineering and Physical Sciences Research Council (EPSRC-UK) within the research project âScrutable Autonomous Systemsâ (Grant No. EP/J012084/1). The authors thank the three anonymous reviewers for their comments, suggestions, and constructive criticisms. Thanks are due to Dr. Nir Oren, for comments on earlier versions of the article, and Mr. Seumas Simpson, for proofreading the manuscript. Any remaining mistakes are the sole responsibility of the authors.Peer reviewedPostprin
Reasoning about coalitional agency and ability in the logics of "bringing-it-about"
The logics of "bringing-it-about" have been part of a prominent tradition for the formalization of individual and institutional agency. They are the logics to talk about what states of affairs an acting entity brings about while abstracting away from the means of action. Elgesem\u27s proposal analyzes the agency of individual agents as the goal-directed manifestation of an individual ability. It has become an authoritative modern reference. The first contribution of this paper is to extend Elgesem\u27s logic of individual agency and ability to coalitions. We present a general theory and later propose several possible specializations. As a second contribution, we offer algorithms to reason with the logics of bringing-it-about and we analyze their computational complexity
- âŠ