Dragan Doder

AAAI Conference 2026 Conference Paper

Rational Revision of Group Intentions

• Nima Motamed
• Natasha Alechina
• Mehdi Dastani
• Dragan Doder

In systems such as group calendars or collaborative platforms, agents make group commitments to future actions that must adapt as new facts or constraints emerge. We develop a formal framework for revising such group intentions in systems where coalitions adopt shared, temporally extended intentions represented in a logic based on Alternating-Time Temporal Logic with strategy contexts. After formulating coherence criteria for systems of group intentions, we establish representation theorems in the style of Katsuno and Mendelzon, showing that revision operators satisfy rationality postulates precisely when they can be represented by preorders on strategy profiles. These results extend classical revision theory by covering non-total preorders and a logic of higher expressive power. Altogether, the framework lays the groundwork for principled revision of group intentions in systems where both coordination and change are essential.

AAAI Conference 2025 Conference Paper

Temporal Causal Reasoning with (Non-Recursive) Structural Equation Models

• Maksim Gladyshev
• Natasha Alechina
• Mehdi Dastani
• Dragan Doder
• Brian Logan

Structural equation models (SEM) are a standard approach to representing causal dependencies between variables. In this paper we propose a new interpretation of existing formalisms in the field of Actual Causality in which SEM's are viewed as mechanisms transforming the dynamics of exogenous variables into the dynamics of endogenous variables. This allows us to combine counterfactual causal reasoning with existing temporal logic formalizms, and to introduce a temporal logic, CPLTL, for causal reasoning about such structures. Then, we demonstrate that the standard restriction to so-called recursive models (with no cycles in the dependency graphs) is not necessary in our approach. This fact provides us extra tools for reasoning about mutually dependent processes and feedback loops. Finally, we introduce the notions of model equivalence for temporal causal models and show that CPLTL has an efficient model-checking procedure.

IJCAI Conference 2024 Conference Paper

Higher-Order Argumentation Frameworks: Principles and Gradual Semantics

• Leila Amgoud
• Dragan Doder
• Marie-Christine Lagasquie-Schiex

The paper investigates how to evaluate elements in complex argumentation frameworks, where both arguments and attacks are weighted and might be attacked by arguments. We propose the first gradual semantics that assign a numerical value to every argument and attack. The value represents the acceptance (seriousness) degree of an argument (attack). We start by highlighting various technical challenges facing semantics in such complex settings, including how to deal with attacks vs arguments, and how to combine their values. We present principles that describe different strategies offered to semantics to meet such challenges. Then, we introduce various semantics per strategy. For instance, some semantics evaluate attacks and arguments in the same way while others, called hybrid, treat them differently. Finally, the principles are used to compare the plethora of novel semantics. The final result is a catalogue of semantics with different formal guarantees and behaviours.

IJCAI Conference 2024 Conference Paper

Revising Beliefs and Intentions in Stochastic Environments

• Nima Motamed
• Natasha Alechina
• Mehdi Dastani
• Dragan Doder

The development of autonomous agents operating in dynamic and stochastic environments requires theories and models of how beliefs and intentions are revised while taking their interplay into account. In this paper, we initiate the study of belief and intention revision in stochastic environments, where an agent's beliefs and intentions are specified in a decidable probabilistic temporal logic. We then provide general Katsuno & Mendelzon-style representation theorems for both belief and intention revision, giving clear semantic characterizations of revision methods.

ECAI Conference 2023 Conference Paper

Dynamic Causality

• Maksim Gladyshev
• Natasha Alechina
• Mehdi Dastani
• Dragan Doder
• Brian Logan 0001

There have been a number of attempts to develop a formal definition of causality that accords with our intuitions about what constitutes a cause. Perhaps the best known is the “modified” definition of actual causality, HPm, due to Halpern. In this paper, we argue that HPm gives counterintuitive results for some simple causal models. We propose Dynamic Causality (DC), an alternative semantics for causal models that leads to an alternative definition of causes. DC ascribes the same causes as HPm on the examples of causal models widely discussed in the literature and ascribes intuitive causes for the kinds of causal models we consider. Moreover, we show that the complexity of determining a cause under the DC definition is lower than for the HPm definition.

ECAI Conference 2023 Conference Paper

Graduality in Probabilistic Argumentation Frameworks

• Jeroen Paul Spaans
• Dragan Doder

Gradual semantics are methods that evaluate overall strengths of individual arguments in graphs. In this paper, we investigate gradual semantics for extended frameworks in which probabilities are used to quantify the uncertainty about arguments and attacks belonging to the graph. We define the likelihoods of an argument’s possible strengths when facing uncertainty about the topology of the argumentation framework. We also define an approach to compare the strengths of arguments in this probabilistic setting. Finally, we propose a method to calculate the overall strength of each argument in the framework, and we evaluate this method against a set of principles.

KR Conference 2023 Conference Paper

Group Responsibility for Exceeding Risk Threshold

• Maksim Gladyshev
• Natasha Alechina
• Mehdi Dastani
• Dragan Doder

The need for tools and techniques to formally analyze and trace the responsibility for unsafe outcomes to decision-making actors is urgent. Existing formal approaches assume that the unsafe outcomes for which actors can be held responsible are actually realized. This paper considers a broader notion of responsibility where unsafe outcomes are not necessarily realized, but their probabilities are unacceptably high. We present a logic combining strategic, probabilistic and temporal primitives designed to express concepts such as the risk of an undesirable outcome and being responsible for exceeding a risk threshold. We demonstrate that the proposed logic is complete and decidable.

IJCAI Conference 2023 Conference Paper

Parametrized Gradual Semantics Dealing with Varied Degrees of Compensation

• Dragan Doder
• Leila Amgoud
• Srdjan Vesic

Compensation is a strategy that a semantics may follow when it faces dilemmas between quality and quantity of attackers. It allows several weak attacks to compensate one strong attack. It is based on compensation degree, which is a tuple that indicates (i) to what extent an attack is weak and (ii) the number of weak attacks needed to compensate a strong one. Existing principles on compensation do not specify the parameters, thus it is unclear whether semantics satisfying them compensate at only one degree or several degrees, and which ones. This paper proposes a parameterised family of gradual semantics, which unifies multiple semantics that share some principles but differ in their strategy regarding solving dilemmas. Indeed, we show that the two semantics taking the extreme values of the parameter favour respectively quantity and quality, while all the remaining ones compensate at some degree. We define three classes of compensation degrees and show that the novel family is able to compensate at all of them while none of the existing gradual semantics does.

FLAP Journal 2023 Journal Article

Probabilistic Deontic Logics for Reasoning about Uncertain Norms.

• Vincent de Wit
• Dragan Doder
• John-Jules Ch. Meyer

In this article, we present a proof-theoretical and model-theoretical approach to probabilistic logic for reasoning about uncertainty about normative state- ments. We introduce two logics with languages that extend both the language of monadic deontic logic and the language of probabilistic logic. The first logic allows statements like “the probability that one is obliged to be quiet is at least 0. 9”. The second logic allows iteration of probabilities in the language. We axiomatize both logics, provide the corresponding semantics and prove that the axiomatizations are sound and complete. We also prove that both logics are decidable. In addition, we show that the problem of deciding satisfiability for the simpler of our two logics is in PSPACE, no worse than that of deontic logic.

IJCAI Conference 2023 Conference Paper

Probabilistic Temporal Logic for Reasoning about Bounded Policies

• Nima Motamed
• Natasha Alechina
• Mehdi Dastani
• Dragan Doder
• Brian Logan

To build a theory of intention revision for agents operating in stochastic environments, we need a logic in which we can explicitly reason about their decision-making policies and those policies' uncertain outcomes. Towards this end, we propose PLBP, a novel probabilistic temporal logic for Markov Decision Processes that allows us to reason about policies of bounded size. The logic is designed so that its expressive power is sufficient for the intended applications, whilst at the same time possessing strong computational properties. We prove that the satisfiability problem for our logic is decidable, and that its model checking problem is PSPACE-complete. This allows us to e. g. algorithmically verify whether an agent's intentions are coherent, or whether a specific policy satisfies safety and/or liveness properties.

LAMAS&SR Workshop 2023 Workshop Paper

Reasoning about Exceeding Risk Threshold

• Maksim Gladyshev
• Natasha Alechina
• Mehdi Dastani
• Dragan Doder

The problem of tracing the responsibility for unsafe outcomes to decision-making actors in multi-agent systems is urgent. While all existing approaches focus on deterministic outcomes, assuming that (a group of) agents can be held responsible for φ only if φ actually happens and agents could act differently to prevent φ, we find this notion of responsibility insufficient in many scenarios. In this work we combine coalition ability operator [G] from [12] with a probabilistic operator Lα from [5] that allow us to reason about probabilities and their changes. This approach allows us to claim that a group of agents can be held responsible for the unsafe outcome even if this outcome does not actually happen, but the group has caused its probability to be increased to an (unacceptably) high level. The proposed logic could be useful for analysing and assigning responsibility to groups of agents for their risky and unsafe behaviors. Finally, we establish (weak) completeness and decidability results for the proposed logic.

LAMAS&SR Workshop 2022 Workshop Paper

A Probabilistic Finite Temporal Logic for Policies and Intentions

• Nima Motamed
• Natasha Alechina
• Mehdi Dastani
• Dragan Doder

AIJ Journal 2022 Journal Article

Evaluation of argument strength in attack graphs: Foundations and semantics

• Leila Amgoud
• Dragan Doder
• Srdjan Vesic

An argumentation framework is a pair made of a graph and a semantics. The nodes and the edges of the graph represent respectively arguments and relations (e. g. , attacks, supports) between arguments while the semantics evaluates the strength of each argument of the graph. This paper investigates gradual semantics dealing with weighted graphs, a family of graphs where each argument has an initial weight and may be attacked by other arguments. It contains four contributions. The first consists of laying the foundations of gradual semantics by proposing key principles on which evaluation of argument strength may be based. Foundations are important not only for a better understanding of the evaluation process in general, but also for clarifying the basic assumptions underlying semantics, for comparing different (families of) semantics, and for identifying families of semantics that have not been explored yet. The second contribution consists of providing a formal analysis and a comprehensive comparison of the semantics that have been defined in the literature for evaluating arguments in weighted graphs. As a third contribution, the paper proposes three novel semantics and shows which principles they satisfy. The last contribution is the implementation and empirical evaluation of the three novel semantics. We show that the three semantics are very efficient in that they compute the strengths of arguments in less than 20 iterations and in a very short time. This holds even for very large graphs, meaning that the three semantics scale very well.

JELIA Conference 2021 Conference Paper

An Epistemic Probabilistic Logic with Conditional Probabilities

• Sejla Dautovic
• Dragan Doder
• Zoran Ognjanovic

Abstract We present a proof-theoretical and model-theoretical approach to reasoning about knowledge and conditional probability. We extend both the language of epistemic logic and the language of linear weight formulas, allowing statements like “Agent Ag knows that the probability of A given B is at least a half”. We axiomatize this logic, provide corresponding semantics and prove that the axiomatization is sound and strongly complete. We also show that the logic is decidable.

AIJ Journal 2020 Journal Article

Intention as commitment toward time

• Marc van Zee
• Dragan Doder
• Leendert van der Torre
• Mehdi Dastani
• Thomas Icard
• Eric Pacuit

In this paper we address the interplay among intention, time, and belief in dynamic environments. The first contribution is a logic for reasoning about intention, time and belief, in which assumptions of intentions are represented by preconditions of intended actions. Intentions and beliefs are coherent as long as these assumptions are not violated, i. e. as long as intended actions can be performed such that their preconditions hold as well. The second contribution is the formalization of what-if scenarios: what happens with intentions and beliefs if a new (possibly conflicting) intention is adopted, or a new fact is learned? An agent is committed to its intended actions as long as its belief-intention database is coherent. We conceptualize intention as commitment toward time and we develop AGM-based postulates for the iterated revision of belief-intention databases, and we prove a Katsuno-Mendelzon-style representation theorem.

IJCAI Conference 2020 Conference Paper

Ranking Semantics for Argumentation Systems With Necessities

• Dragan Doder
• Srdjan Vesic
• Madalina Croitoru

Bipolar argumentation studies argumentation graphs where attacks are combined with another relation between arguments. Many kind of relations (e. g. deductive support, evidential support, necessities etc. ) have been defined and investigated from a Dung semantics perspective. We place ourselves in the context of argumentation systems with necessities and provide the first study to investigate ranking semantics in this setting. To this end, we (1) provide a set of postulates specifically designed for necessities and (2) propose the first ranking-based semantics in the literature to be shown to respect these postulates.

IJCAI Conference 2019 Conference Paper

Compilation of Logical Arguments

• Leila Amgoud
• Dragan Doder

Several argument-based logics have been defined for handling inconsistency in propositional knowledge bases. We show that they may miss intuitive consequences, and discuss two sources of this drawback: the definition of logical argument i) may prevent formulas from being justified, and ii) may allow irrelevant information in argument's support. We circumvent these two issues by considering a general definition of argument and compiling each argument. A compilation amounts to forgetting in an argument's support any irrelevant variable. This operation returns zero, one or several concise arguments, which we then use in an instance of Dung's abstract framework. We show that the resulting logic satisfies existing rationality postulates, namely consistency and closure under deduction. Furthermore, it is more productive than the existing argument-based and coherence-based logics.

AAMAS Conference 2019 Conference Paper

Gradual Semantics Accounting for Varied-Strength Attacks

• Leila Amgoud
• Dragan Doder

KR Conference 2018 Conference Paper

Gradual semantics accounting for similarity between arguments

• Leila Amgoud
• Elise Bonzon
• Jérôme Delobelle
• Dragan Doder
• Sébastien Konieczny
• Nicolas Maudet

Argumentation is a reasoning model based on the justification of claims by arguments. Often, arguments to be considered are not completely independent, two arguments can be related for different reasons, they may overlap, or given by two persons that make similar statements during a debate, but express them differently, etc. This paper studies for the first time the impact of similarity (i. e. , when pairs of arguments are related) in the context of gradual evaluation in abstract argumentation. We present principles that a semantics accounting for similarities should satisfy, and show how to extend gradual semantics for this purpose. We propose three original methods to do so, and study their properties. In particular, the new semantics are evaluated with respect to the new principles, and others from the literature.

KR Conference 2018 Short Paper

Gradual Semantics for Weighted Graphs: An Unifying Approach

• Leila Amgoud
• Dragan Doder

The paper bridges the gap between two general settings of gradual semantics for weighted argumentation graphs: the evaluation method setting (EMS) and the principle-based one (PBS). The former defines a semantics by three aggregation functions, each of which satisfies specific properties. The latter considers a semantics as any function that follows some high-level principles. The paper shows that (EMS) is one way of defining semantics that satisfy principles. Indeed, some principles follow from properties of aggregation functions.

IJCAI Conference 2017 Conference Paper

Acceptability Semantics for Weighted Argumentation Frameworks

• Leila Amgoud
• Jonathan Ben-Naim
• Dragan Doder
• Srdjan Vesic

The paper studies semantics that evaluate arguments in argumentation graphs, where each argument has a basic strength, and may be attacked by other arguments. It starts by defining a set of principles, each of which is a property that a semantics could satisfy. It provides the first formal analysis and comparison of existing semantics. Finally, it defines three novel semantics that satisfy more principles than existing ones.

ECAI Conference 2016 Conference Paper

AGM-Style Revision of Beliefs and Intentions

• Marc van Zee
• Dragan Doder

We introduce a logic for temporal beliefs and intentions based on Shoham's database perspective and we formalize his coherence conditions on beliefs and intentions. In order to do this we separate strong beliefs from weak beliefs. Strong beliefs are independent from intentions, while weak beliefs are obtained by adding intentions to strong beliefs and everything that follows from that. We provide AGM-style postulates for the revision of strong beliefs and intentions: strong belief revision may trigger intention revision, but intention revision may only trigger revision of weak beliefs. After revision, the strong beliefs are coherent with the intentions. We show in a representation theorem that a revision operator satisfying our postulates can be represented by a pre-order on interpretations of the beliefs, together with a selection function for the intentions.

KR Conference 2016 Conference Paper

Ranking Arguments With Compensation-Based Semantics

• Leila Amgoud
• Jonathan Ben-Naim
• Dragan Doder
• Srdjan Vesic

In almost all existing semantics in argumentation, a strong attack has a lethal effect on its target that a set of several weak attacks may not have. This paper investigates the case where several weak attacks may compensate one strong attack. It defines a broad class of ranking semantics, called α−BBS, which satisfy compensation. α−BBS assign a burden number to each argument and order the arguments with respect to those numbers. We study formal properties of α−BBS, implement an algorithm that calculates the ranking, and perform experiments that show that the approach computes the ranking very quickly. Moreover, an approximation of the ranking can be provided at any time. p q r a p s b F2 v t p An argumentation framework consists of an argumentation graph, that is arguments and attacks between them, and a semantics for evaluating the arguments, and thus for specifying which arguments are acceptable. The most dominant semantics in the literature are those that compute extensions of arguments, initially proposed by Dung (1995). Such semantics are based on the assumption that a successful attack completely destroys its target. Consequently, several successful attacks cannot destroy the target at a greater extent. There are applications where this assumption makes perfect sense (Dung 1995). In other applications, like decision making or dialogues, an attack only weakens its target. Think about a committee which recruits young researchers. Once an argument against a candidate is given, even if this argument is attacked, the initial argument is still considered by the members of the committee (but with a lower strength). Consequently, one attack does not necessarily have the same effect as several attacks. Consider argumentation graph F1 from Figure 1. Arguments a and b are both attacked by strong (i. e. non attacked) arguments. However, b is weakened by more attacks, thus a can be seen as more acceptable than b. Note that the number of attackers plays a role in this example. A similar reasoning holds for F2. Indeed, b should be more acceptable than a since a is weakened whereas b is not. In graph F3, the arguments a and b have the same number of attackers. However, the a b F1

UAI Conference 2015 Conference Paper

A Probabilistic Logic for Reasoning about Uncertain Temporal Information

• Dragan Doder
• Zoran Ognjanovic

The main goal of this work is to present the proof-theoretical and model-theoretical approach to a probabilistic logic which allows reasoning about temporal information. We extend both the language of linear time logic and the language of probabilistic logic, allowing statements like “A will always hold”and “the probability that A will hold in next moment is at least the probability that B will always hold, ” where A and B are arbitrary statements. We axiomatize this logic, provide corresponding semantics and prove that the axiomatization is sound and strongly complete. We show that the problem of deciding decidability is PSPACE-complete, no worse than that of linear time logic.

IJCAI Conference 2015 Conference Paper

AGM Revision of Beliefs about Action and Time

• Marc van Zee
• Dragan Doder
• Mehdi Dastani
• Leendert van der Torre

The AGM theory of belief revision is based on propositional belief sets. In this paper we develop a logic for revision of temporal belief bases, containing expressions about temporal propositions (tomorrow it will rain), possibility (it may rain tomorrow), actions (the robot enters the room) and preand post-conditions of these actions. We prove the Katsuno-Mendelzon and the Darwiche-Pearl representation theorems by restricting the logic to formulas representing beliefs up to certain time. We illustrate our belief change model through several examples.

JELIA Conference 2014 Conference Paper

Probabilistic Abstract Dialectical Frameworks

• Sylwia Polberg
• Dragan Doder

Abstract Although Dung’s frameworks are widely approved tools for abstract argumentation, their abstractness makes expressing notions such as support or uncertainty very difficult. Thus, many of their generalizations were created, including the probabilistic argumentation frameworks (PrAFs) and the abstract dialectical frameworks (ADFs). While the first allow modeling uncertain arguments and attacks, the latter can handle various dependencies between arguments. Although the actual probability layer in PrAFs is independent of the chosen semantics, new relations pose new challenges and new interpretations of what is the probability of a relation. Thus, the methodology for handling uncertainties cannot be shifted to more general structures without any further thought. In this paper we show how ADFs are extended with probabilities.