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Moral luck is the phenomenon that agents are not always held accountable for performance of a choice that under normal circumstances is likely to result in a state that is considered bad, but where due to some unexpected interaction the bad outcome does not obtain. We can also speak of `moral misfortune' in the mirror situation where an agent chooses the good thing but the outcome is bad. This paper studies formalizations of moral and legal luck (and moral and legal misfortune). The three ingredients essential to modelling luck of these two different kinds are (1) indeterminacy of action effects, (2) determination on the part of the acting agent, (3) the possibility of evaluation of acts and/or their outcomes relative to a normative moral or legal code. The first, indeterminacy of action, is modelled by extending stit logic by allowing choices to have a probabilistic effect. The second, deliberateness of action, is modelled by (a) endowing stit operators with the possibility to specify a lower bound on the change of success, and (b) by introducing the notion of attempt as a maximisation of the probability of success. The third, evaluation relative to a moral or legal code, is modelled using Anderson's reduction of normative truth to logical truth. The conclusion will be that the problems embodied by the phenomenon of moral luck may be introduced by confusing it with legal luck. Formalizations of both forms are given. [ABSTRACT FROM AUTHOR]

The purpose of this contribution is to set up a language to evaluate the results of concerted action among interdependent agents against predetermined properties that we can recognise as desirable from a deontic point of view. Unlike the standard view of logics to reason about coalitionally rational action, the capacity of a set of agents to take a rational decision will be restricted to what we will call agreements, that can be seen as solution concepts to a dependence structure present in a certain game. The language will identify in concise terms those agreements that act accordingly or disaccordingly with the desirable properties arbitrarily set up in the beginning, and will reveal, by logical reasoning, a variety of structural properties of this type of collective action. [ABSTRACT FROM AUTHOR]

Reasoning about norms and time is of central concern to the regulation or control of the behavior of a multiagent system. In this paper we introduce a representation of normative systems that distinguishes between norms and the detached obligations of agents over time, leading to a simple and therefore practical way to reason about norms, obligations, time and agents. We consider the reasoning tasks to determine whether a norm is redundant in a normative system and whether two normative systems are equivalent. In the former case the redundant norm might be removed. In the latter case one norm might be replaced by the other. It is well known that properties concerning iterated or deontic detachment no longer hold when reasoning with multiple agents or with obligations over time. Yet, earlier approaches to reasoning about norms rarely consider the intricacies of time. We show how norms can be used to define the persistence of obligations of agents over time. We illustrate our approach by discussing three ways to relate norms and obligations of agents over time. Also we show how these three ways can be characterized. [ABSTRACT FROM AUTHOR]

The aim of this paper is to raise awareness of some issues in designing (formal) models for norm change. I start by positioning this research in a broader context. Then I will briefly recall several concepts and problems from deontic logic, which is the field primarily concerned with notions like `norm΄, `obligation΄, `right΄, etc. Then I proceed with what I regard the main contribution of the paper: the distinction of four categories of problems one faces when thinking about formal logical models for norm change. [ABSTRACT FROM AUTHOR]

This paper presents a complete temporal STIT logic for reasoning about multi-agency. I discuss its application for reasoning about norms, knowledge, autonomy, and other multi-agent concepts. Also I give some arguments in favor of taking STIT formalisms instead of dynamic logics as the basis for logics for representing multi-agent system notions. [ABSTRACT FROM AUTHOR]

In this paper, we propose a representation of excuses in the context of multiagent systems. We distinguish five classes of excuses, taking as starting point both jurisprudential and philosophical studies about this topic, and we discuss their acceptance criteria. We highlight the following classes of excuses: epistemic excuses, power-based excuses, norm-based excuses, counts as-based excuses and social-based excuses and we represent them using social dependence networks. The acceptance criteria individuate those excuses which success in maintaining the trust of the other agents, e.g. in the context of social networks, excuses based on norms seem better than counts as-based ones in achieving this aim. [ABSTRACT FROM AUTHOR]

Coalition Logic does not explicitly talk about the effects of a coalitional move on the strategic ability of the remaining players, while in Game Theory reasoning patterns involving this concept often occur. To fill this gap, we study an update operator for strategic ability update in coalition structures. Its formal connections with the update operators known from Dynamic Epistemic Logic will be discussed. [ABSTRACT FROM AUTHOR]

Within a STIT framework, this paper presents a logical study of the interaction between `ought-to-do΄, and an epistemic notion of `knowingly doing΄. We start out with some motivating examples concerning the interaction between action, obligation and knowledge. Then we present a complete temporal STIT logic including operators for action, obligation and knowledge. We use the logic to analyze the examples and discuss open problems. [ABSTRACT FROM AUTHOR]

The paper discusses the interaction properties between preference and choice of coalitions in a strategic interaction. A language is presented to talk about the conflict between coalitionally optimal and socially optimal choices. Norms are seen as social constructions that enable to enforce socially desirable outcomes. [ABSTRACT FROM AUTHOR]

Reasoning about norms and time is of central concern to the regulation or control of the behavior of a multi-agent system. In earlier work we introduce a representation of normative systems that distinguishes between norms and the detached obligations of agents over time. In this paper we consider constitutive norms and the detached counts-as conditionals and institutional facts in this framework, we introduce deadlines in the regulative norms, and we consider the corresponding role of violations. We focus on the reasoning tasks to determine whether a constitutive or regulative norm is redundant in a normative system and whether two normative systems are equivalent. We distinguish counts-as equivalence, institutional equivalence, obligation equivalence and violation equivalence, depending on whether we are interested in all normative consequences, or only a subset of them. For the various notions of equivalence, we give sound and complete characterizations. [ABSTRACT FROM AUTHOR]

We study a logical property that concerns the preservation of future directed obligations that have not been fulfilled yet. We call this property ΄propagation property΄. The goal is to define a combination of temporal and deontic logics which satisfies this property. Our starting point is the product of temporal and deontic logics. We investigate some modifications of the semantics of the product in order to satisfy the propagation property, without losing too much of the basic properties of the product. We arrive at a semantics in which we only consider ideal histories that share the same past as the current one, and that enables an interesting characterization of the states in which obligations propagate: these are the states where there are no violations of present directed obligations. [ABSTRACT FROM AUTHOR]

The aim of the work is to provide a language to reason about closed-world interaction, that is all those situations in which the outcomes of an interaction can be determined by the agents themselves and in which Nature does not play an active role. We formalize this intuition by identifying all such interactions and axiomatizing their logic. We apply the formal tools to reason about games and their regulation. [ABSTRACT FROM AUTHOR]

In this paper we extend earlier work on deontic deadlines in CTL to the framework of alternating time temporal logic (ATL). The resulting setting enables us to model several concepts discussed in the deontic logic literature. Among the issues discussed are: conditionality, ought implies can, deliberateness, settledness, achievement obligations versus maintenance obligations and deontic detachment. We motivate our framework by arguing for the importance of temporal order obligations, from the standpoint of agent theory as studied in computer science. In particular we will argue that in general achievement obligations cannot do without a deadline condition saying the achievement has to take place before it. Then we define our logic as a reduction to ATL. We demonstrate the applicability of the logic by discussing a possible solution to Chisholm's paradox. The solution differs considerably from other known temporal approaches to the paradox. [ABSTRACT FROM AUTHOR]

This paper extends a programming language for implementing cognitive agents with the capability to explicitly represent beliefs and reason about them. In this programming language, the beliefs of agents are implemented by modal logic programs, where beliefs are represented by explicit modal operators. A distinction is made between a belief base language that can be used to represent an agent's beliefs, and a belief query language that can be used to express queries to the agent's belief base. We adopt and modify a proof procedure that decides if a belief query formula is derivable from the belief base of an agent. We show that the presented proof procedure is sound. [ABSTRACT FROM AUTHOR]

A problem in many formalisms for reasoning about multi-agent systems, like ATL or PDL, is the inability to express that a certain complex action (as in PDL), choice or strategy (as in ATL) is performed by an agent. However, in so called STIT-logics, this is exactly the main operator: seeing to it that a certain condition is achieved. Here we present an extension of ATL, introducing ideas from STIT-theory, that can express that a group of agents A perform a certain strategy. As a demonstration of the applicability of the formalism, we show how it sheds new light on the problem of modelling ‘uniform strategies' in epistemic versions of ATL. [ABSTRACT FROM AUTHOR]

This paper defines a possible semantics for deadline obligations. Also, we make explicit several choices to be made in defining the semantics of deadline obligations. We characterize deontic deadline operators in CTL, minimally extended with propositional violation constants. The advantage of this reduction approach is that formal reasoning can be performed in CTL. [ABSTRACT FROM AUTHOR]