Jan M. Broersen

EUMAS Conference 2025 Conference Paper

BOID for smart scheduling: Integrating default logic and generative models for interpretable personalization

• Stipe Pandžić
• Fabio Dijkshoorn
• Jan M. Broersen

TARK Conference 2021 Conference Paper

A Deontic Stit Logic Based on Beliefs and Expected Utility

• Aldo Iván Ramírez Abarca
• Jan M. Broersen

The formalization of action and obligation using logic languages is a topic of increasing relevance in the field of ethics for AI. Having an expressive syntactic and semantic framework to reason about agents' decisions in moral situations allows for unequivocal representations of components of behavior that are relevant when assigning blame (or praise) of outcomes to said agents. Two very important components of behavior in this respect are belief and belief-based action. In this work we present a logic of doxastic oughts by extending epistemic deontic stit theory with beliefs. On one hand, the semantics for formulas involving belief operators is based on probability measures. On the other, the semantics for doxastic oughts relies on a notion of optimality, and the underlying choice rule is maximization of expected utility. We introduce an axiom system for the resulting logic, and we address its soundness, completeness, and decidability results. These results are significant in the line of research that intends to use proof systems of epistemic, doxastic, and deontic logics to help in the testing of ethical behavior of AI through theorem-proving and model-checking.

JELIA Conference 2019 Conference Paper

A Logic of Objective and Subjective Oughts

• Aldo Iván Ramírez Abarca
• Jan M. Broersen

Abstract The relation between agentive action, knowledge, and obligation is central to the understanding of responsibility – a main topic in Artificial Intelligence. Based on the view that an appropriate formalization of said relation would contribute to the development of ethical AI, we point out the main characteristics of a logic for objective and subjective oughts that was recently introduced in the literature. This logic extends the traditional stit paradigm with deontic and epistemic operators, and provides a semantics that deals with Horty’s puzzles for knowledge and obligation. We provide an axiomatization for this logic, and address its soundness and completeness with respect to a class of relevant models.

FLAP Journal 2018 Journal Article

On Elitist Lifting and Consistency in Structured Argumentation.

• Sjur K. Dyrkolbotn
• Truls Pedersen
• Jan M. Broersen

We address the question of how to lift an ordering over rules to an ordering over arguments (sets of rules) that is well-behaved. It has been shown that so-called elitist lifting may lead to inconsistencies. We give restrictions on the underlying rule-ordering that avoid inconsistency. Then we show that a recently proposed solution – so-called disjoint strict lifting – that was introduced to address conceptual objections, also leads to inconsistency. We show that another recent proposal, telling us to reorder rule-orderings to take argument structure into account before lifting, is able to avoid conceptual problems without leading to any new inconsistencies. We generalise this approach by defining what we call structural rule-orderings and show a correspondence between weakest link and last link lifting of such orderings, which has interesting consequences for the question of consistency. We arrive at our results using a signature-based approach to structured argumentation. Instead of settling on a given framework, such as ASPIC+, we define an argumentation language that allows us to express only those properties of argumentation systems we need to establish our results. This abstract approach simplifies and clarifies the technical work while making our contribution more general.

LORI Conference 2009 Conference Paper

An Update Operator for Strategic Ability

• Paolo Turrini
• Jan M. Broersen
• Rosja Mastop
• John-Jules Ch. Meyer

Abstract 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.

JELIA Conference 2008 Conference Paper

A Logic for Closed-World Interaction

• Jan M. Broersen
• Rosja Mastop
• John-Jules Ch. Meyer
• Paolo Turrini

Abstract 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.

ECAI Conference 2008 Conference Paper

Conditional Norms and Dyadic Obligations in Time

• Jan M. Broersen
• Leendert W. N. van der Torre

ECAI Conference 2008 Conference Paper

Organizing Coherent Coalitions

• Jan M. Broersen
• Rosja Mastop
• John-Jules Ch. Meyer
• Paolo Turrini

In this paper we provide and discuss a language to talk about coherence, a property of interaction that ensures players' abilities non to contradict one other and the empty coalition not to make active choices. With this property we can model a closed-world interaction, such as those of a Coordination Game or of a Prisoner Dilemma, where all the outcomes are determined only by the choices of the agents that are present.

TARK Conference 2007 Conference Paper

A normal simulation of coalition logic and an epistemic extension

• Jan M. Broersen
• Andreas Herzig
• Nicolas Troquard

In this paper we show how coalition logic can be reduced to the fusion of a normal modal STIT logic for agency and a standard normal temporal logic for discrete time, and how this multi-modal system can be suitably extended with an epistemic modality. Both systems are complete, and we provide a new axiomatization for the STIT-fragment. The epistemic extension enables us to express that agents see to something under uncertainty about the present state or uncertainty about which action is being taken. In accordance with established terminology in the planning community, we call this version of STIT the ‘conformant STIT’. The conformant STIT enables us to express that agents are able to perform a uniform strategy. As a final word of recommendation for this paper we want to point out that its subject is at the junction of four academic fields, viz. modal logic, philosophy, game-theory and AI-planning.

JELIA Conference 2006 Conference Paper

A STIT-Extension of ATL

• Jan M. Broersen
• Andreas Herzig
• Nicolas Troquard

Abstract 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.

JELIA Conference 2004 Conference Paper

On the Logic of 'Being Motivated to Achieve rho, Before delta'

• Jan M. Broersen

Abstract This paper studies the logic of modalities for motivational attitudes (desires, obligations, wishes, wants, intentions, etc.) that come with a deadline condition. For instance, an agent may want to get home before it starts raining. We use a ‘reduction approach’ from deontic logic to characterize two separate semantic definitions for these motivational modalities in CTL. The main advantage of applying reductions is that the formal reasoning can be performed entirely in CTL. We claim that the reduction approach applies to any motivational modality.

NMR Workshop 2002 Conference Paper

The mutual exclusion problem in reasoning about action and change

• Jan M. Broersen
• John-Jules Ch. Meyer
• Roel J. Wieringa

We describe a new aspect of the qualification problem that arises in the context of concurrent action. The qualification problem is typically approached by formulating principles of maximal qualification. However, for concurrent action the qualification problem is exponentionally harder, because we have to specify all mutual exclusions explicitly. We identify the problem encountered as ‘the mutual exclusion problem’. We argue that its solution may involve a default position regarding the qualification of concurrent actions relative to the qualification of constituent concurrent parts of an action. We describe the mutual exclusion problem in detail and propose a possible solution in terms of intended modal action models.