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Sylvie Doutre

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14 papers

2 author rows

AAMAS Conference 2023 Conference Paper

Visual Explanations for Defence in Abstract Argumentation

Sylvie Doutre
Théo Duchatelle
Marie-Christine Lagasquie-Schiex

The Verification Problem in abstract argumentation consists in checking whether a set is acceptable under a given semantics in a given argumentation graph. Explaining why the answer is so is the challenge tackled by our work. In this extended abstract, we focus on a small part of this aim considering only the defence principle and proposing explanations in order to explain why a subset of arguments defends all its elements. These explanations are visual, in the sense that they take the form of subgraphs of the initial argumentation framework. They form a class, whose properties are investigated.

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FLAP Journal 2021 Journal Article

Enforcement in Formal Argumentation.

Ringo Baumann
Sylvie Doutre
Jean-Guy Mailly
Johannes P. Wallner

Within argumentation dynamics, a major strand of research is concerned with how changing an argumentation framework affects the acceptability of arguments, and how to modify an argumentation framework in order to guarantee that some arguments have a given acceptance status. In this chapter, we overview the main approaches for enforcement in formal argumentation. We mainly focus on extension enforcement, i.e., on how to modify an argumentation framework to ensure that a given set of arguments becomes (part of) an extension. We present different forms of extension enforcement defined in the literature, as well as several possibility and impossibility results. The question of minimal change is also considered, i.e., what is the minimal number of modifications that must be made to the argumentation framework for enforcing an extension. Computational complexity and algorithms based on a declarative approach are discussed. Finally, we briefly describe several notions that do not directly fit our definition of extension enforcement, but are closely related.

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TARK Conference 2019 Conference Paper

Aggregation in Value-Based Argumentation Frameworks

Grzegorz Lisowski
Sylvie Doutre
Umberto Grandi

Value-based argumentation enhances a classical abstract argumentation graph - in which arguments are modelled as nodes connected by directed arrows called attacks - with labels on arguments, called values, and an ordering on values, called audience, to provide a more fine-grained justification of the attack relation. With more than one agent facing such an argumentation problem, agents may differ in their ranking of values. When needing to reach a collective view, such agents face a dilemma between two equally justifiable approaches: aggregating their views at the level of values, or aggregating their attack relations, remaining therefore at the level of the graphs. We explore the strenghts and limitations of both approaches, employing techniques from preference aggregation and graph aggregation, and propose a third possibility aggregating rankings extracted from given attack relations.

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EUMAS Conference 2017 Conference Paper

Comparison Criteria for Argumentation Semantics

Sylvie Doutre
Jean-Guy Mailly

Abstract Argumentation reasoning is a way for agents to evaluate a situation. Given a framework made of conflicting arguments, a semantics allows to evaluate the acceptability of the arguments. It may happen that the semantics associated to the framework has to be changed. In order to perform the most suitable change, the current and a potential new semantics have to be compared. Notions of difference measures between semantics have already been proposed, and application cases where they have to be minimized when a change of semantics has to be performed, have been highlighted. This paper develops these notions, it proposes an additional kind of difference measure, and shows application cases where measures may have to be maximized, and combined.

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KR Conference 2014 Conference Paper

A dynamic logic framework for abstract argumentation

Sylvie Doutre
Andreas Herzig
Laurent Perrussel

the semantics. This is done in an extension of the language of attack variables by variables representing argument acceptance. Based on such a logical representation, several authors have recently investigated the dynamics of the AF, such as (Baumann 2012; Booth et al. 2013; Bisquert et al. 2013; Coste-Marquis et al. 2013). They start by distinguishing several kinds of modification of the AF, such as the addition or the removal of attacks, or the enforcement of the acceptability of an argument a (e. g. such that a is part of at least one extension). All these papers build on previous work in belief change, either referring to AGM theory (Alchourrón, Gärdenfors, and Makinson 1985), such as (Booth et al. 2013; Coste-Marquis et al. 2013), or to KM theory (Katsuno and Mendelzon 1992), such as (Bisquert et al. 2013). They express the modification as a logical formula describing some goal, i. e., a property that AF should satisfy: the task is to revise/update AF so that this formula is true. The above papers do not provide a single framework encompassing at the same time AF, the logical definition of the enforcement constraint and the change operations: there is usually one language for representing AF and another language for representing constraints, plus some definitions in the metalanguage connecting them. This has motivated us to provide a general, unified logical framework for the representation and the update of argumentation frameworks. We make use of a flexible yet simple logic: Dynamic Logic of Propositional Assignments, abbreviated DL-PA (Balbiani, Herzig, and Troquard 2013). DL-PA is a simple instantiation of Propositional Dynamic Logic PDL (Harel 1984; Harel, Kozen, and Tiuryn 2000) whose atomic programs are assignments of propositional variables to either true or false. Complex programs are built then from atomic programs by the standard PDL program operators of sequential composition, nondeterministic composition, and test. We here moreover add a less frequently considered PDL program operator, namely the converse operator. The language of DL-PA has formulas of the form hπiϕ and [π]ϕ, where π is a program and ϕ is a formula. The former expresses that ϕ is true after some possible execution of π, and the latter expresses that ϕ is true after every possible execution of π. It is shown in (Balbiani, Herzig, and Troquard 2013) that every DL-PA formula can be reduced to an equivalent propositional formula. The reduction extends to the converse operator in a straight- We provide a logical analysis of abstract argumentation frameworks and their dynamics. Following previous work, we express attack relation and argument status by means of propositional variables and define acceptability criteria by formulas of propositional logic. We here study the dynamics of argumentation frameworks in terms of basic operations on these propositional variables, viz. change of their truth values. We describe these operations in a uniform way within a well-known variant of Propositional Dynamic Logic PDL: the Dynamic Logic of Propositional Assignments, DL-PA. The atomic programs of DL-PA are assignments of propositional variables to truth values, and complex programs can be built by means of the connectives of sequential and nondeterministic composition and test. We start by showing that in DL-PA, the construction of extensions can be performed by a DL-PA program that is parametrized by the definition of acceptance. We then mainly focus on how the acceptance of one or more arguments can be enforced and show that this can be achieved by changing the truth values of the propositional variables describing the attack relation in a minimal way.

AAMAS Conference 2007 Conference Paper

Arguing for Gaining Access to Information

Sylvie Doutre
Peter McBurney
Laurent Perrussel
Jean-Marc Thevenin

This paper presents a protocol for agents engaged in argumentation over access to information sources. Obtaining relevant information is essential for agents engaged in autonomous, goal-directed behavior, but access to such information is usually controlled by other autonomous agents having their own goals. Because these various goals may be in conflict with one another, rational interactions between the two agents may take the form of a dialog, in which requests for information are successively issued, considered, justified and criticized. Even when the agents involved in such discussions agree on all the arguments for and the arguments against granting access to some information source, they may still disagree on their preferences between these arguments.

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AIJ Journal 2007 Journal Article

Audiences in argumentation frameworks

Trevor J.M. Bench-Capon
Sylvie Doutre
Paul E. Dunne

Although reasoning about what is the case has been the historic focus of logic, reasoning about what should be done is an equally important capacity for an intelligent agent. Reasoning about what to do in a given situation—termed practical reasoning in the philosophical literature—has important differences from reasoning about what is the case. The acceptability of an argument for an action turns not only on what is true in the situation, but also on the values and aspirations of the agent to whom the argument is directed. There are three distinctive features of practical reasoning: first, that practical reasoning is situated in a context, directed towards a particular agent at a particular time; second, that since agents differ in their aspirations there is no right answer for all agents, and rational disagreement is always possible; third, that since no agent can specify the relative priority of its aspirations outside of a particular context, such prioritisation must be a product of practical reasoning and cannot be used as an input to it. In this paper we present a framework for practical reasoning which accommodates these three distinctive features. We use the notion of argumentation frameworks to capture the first feature. An extended form of argumentation framework in which values and aspirations can be represented is used to allow divergent opinions for different audiences, and complexity results relating to the extended framework are presented. We address the third feature using a formal description of a dialogue from which preferences over values emerge. Soundness and completeness results for these dialogues are given.

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IJCAI Conference 2005 Conference Paper

Discovering Inconsistency through Examination Dialogues

Paul E. Dunne
Sylvie Doutre
Trevor

In this paper we introduce examination dialogues, an addition to the dialogue typology of Walton and Krabbe. In educational settings the purpose of dialogue is often to elicit the position of a student, e. g. to test understanding. In other settings, a frequently adopted tactic is to attack an opponent’s stance by exposing internal inconsistencies in their argument. In real debate such inconsistencies will often be rather more subtle than elementary logical fallacies since they arise from contradictions apparent in the opponent’s value system. Protagonists will be better positioned to judge the applicability of this tactic as more information is determined concerning the exact nature of their opponent’s case, e. g. the arguments favoured and values endorsed. One obstacle, however, is that following a request to state a view, the challenged party may refuse to comment. In this paper we present an approach to modelling the evolution of examination dialogues based on the concept of value-based argument frameworks and outline some algorithmic issues regarding argument selection.

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IJCAI Conference 2005 Conference Paper

Explaining preferences with argument positions

Sylvie Doutre
Trevor Bench-Capon
Paul E

When deciding what to do agents must choose among alternative actions and different agents may make different choices according to what they wish to achieve in the light of their preferences and values. It cannot be assumed, however, that agents have a conscious understanding of their value preferences independent of the reasoning situations in which they engage. In this paper we consider an extension to a generic framework for reasoning about arguments justifying actions in terms of values in which the preferences amongst values emerge from the reasoning process.

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KR Conference 2004 Conference Paper

Characterization of semantics for argument systems

Philippe Besnard
Sylvie Doutre

We consider Dung’s argumentation framework, in which an argument system consists of a set of arguments and a binary relation between arguments representing the notion of a conflict. The semantics given by Dung define (with respect to each argument system) acceptable sets of arguments called extensions. For his so-called stable semantics, Dung also gives an alternative definition in terms of an equation that a set satisfies if and only if that set is a stable extension. However, neither the original definition nor the equation reflect the fact that the stable semantics (similarly to all of Dung’s semantics) rely upon the notion of an admissible set. Moreover, none of Dung’s other semantics have been characterized by such an equation. Our first goal is to provide such characterizations for the other semantics: We capture Dung’s semantics by means of equations that a set satisfies if and only if it is an extension under the semantics at hand. Not only do we give such equations, but we also take care of providing them as a unified characterization expressing the common grounds of Dung’s semantics. Beyond Dung’s semantics, we are interested in semantics (within Dung’s argumentation framework) relying upon the notion of an admissible set. Our second goal is to show that many of those semantics are captured like Dung’s, using the same unified characterization.

NMR Workshop 2004 Conference Paper

Checking the acceptability of a set of arguments

Philippe Besnard
Sylvie Doutre

Considering Dung’s argumentation framework and semantics, we are interested in the problem which consists in deciding whether a set of arguments is acceptable under a given semantics. We look at three approaches. The first one consists in testing whether the set satisfies an equation; In particular, we look at the equations presented in (Dung 1995; Besnard & Doutre 2004). The second approach consists in testing whether the set is a model of a propositional formula and the third one consists in testing the satisfiability of a propositional formula.

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JELIA Conference 2004 Conference Paper

On Sceptical Versus Credulous Acceptance for Abstract Argument Systems

Sylvie Doutre
Jérôme Mengin

Abstract At a high level of abstraction, many systems of argumentation can be represented by a set of abstract arguments, and a binary relation between these abstract arguments describing how they contradict each other. Acceptable sets of arguments, called extensions, can be defined as sets of arguments that do not contradict one another, and attack all their attackers. We are interested in this paper in answering the question: is a given argument in all extensions of an argumentation system? In fact, what is likely to be useful in AI systems is not a simple yes/no answer, but some kind of well-argued answer, called a proof: if an argument is in every extension, why is it so? Several authors have described proofs that explain why a given argument is in at least one extension. In this paper, we show that a proof that an argument is in every extension can be a proof that some meta -argument is in at least one extension of a meta -argumentation system: this meta-argumentation system describes relationships between sets of arguments of the initial system.

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NMR Workshop 2004 Conference Paper

On sceptical vs credulous acceptance for abstract argument systems

Sylvie Doutre
Jérôme Mengin

At a high level of abstraction, many systems of argumentation can be represented by a set of abstract arguments, and a binary relation between these abstract arguments describing how they contradict each other. Acceptable sets of arguments, called extensions, can be defined as sets of arguments that do not contradict one another, and attack all their attackers. We are interested in this paper in answering the question: is a given argument in all extensions of an argumentation system? In fact, what is likely to be useful in AI systems is not a simple yes/no answer, but some kind of well-argued answer, called a proof: if an argument is in every extension, why is it so? We describe a close connection between this problem and proofs that some meta-argument is in at least one extension of a meta-argumentation system, describing relationships between sets of arguments of the initial system.

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NMR Workshop 2002 Conference Paper

"Minimal defence": a refinement of the preferred semantics for argumentation frameworks

Claudette Cayrol
Sylvie Doutre
Marie-Christine Lagasquie-Schiex
Jérôme Mengin

Dung’s abstract framework for argumentation enables a study of the interactions between arguments based solely on an “attack” binary relation on the set of arguments. Various ways to solve conflicts between contradictory pieces of information have been proposed in the context of argumentation, nonmonotonic reasoning or logic programming, and can be captured by appropriate semantics within Dung’s framework. A common feature of these semantics is that one can always maximize in some sense the set of acceptable arguments. We propose in this paper to extend Dung’s framework in order to allow for the representation of what we call “restricted” arguments: these arguments should only be used if absolutely necessary, that is, in order to support other arguments that would otherwise be defeated. We modify Dung’s preferred semantics accordingly: a set of arguments becomes acceptable only if it contains a minimum of restricted arguments, for a maximum of unrestricted arguments.

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