73 research outputs found
Summary Report of The First International Competition on Computational Models of Argumentation
No full textComputational models of argumentation are an active research discipline within Artificial Intelligence that has grown since the beginning of the 1990s (Dung 1995).
While still a young field when compared to areas such as SAT solving and Logic Programming, the argumentation community is very active, with a conference series (COMMA, which began in 2006) and a variety of workshops and special issues of journals. Argumentation has also worked its way into a variety of applications. For example, Williams et al. (2015) described how argumentation techniques are used for recommending cancer treatments, while Toniolo et
al. (2015) detail how argumentation-based techniques can support critical thinking and collaborative scientific inquiry or intelligence analysis.
Many of the problems that argumentation deals with are computationally difficult, and applications utilising argumentation therefore require efficient solvers. To encourage this line of research, we organised the First International
Competition on Computational Models of Argumentation (ICCMA), with the intention of assessing and promoting state of the art solvers for abstract argumentation problems, and to identify families of challenging benchmarks for
such solvers.
The objective of ICCMA’15 is to allow researchers to compare the performance of different solvers systematically on common benchmarks and rules. Moreover, as witnessed by competitions in other AI disciplines such as planning and SAT solving, we see ICCMA as a new pillar of the community which provides information and insights on the current state of the art, and highlights future
challenges and developments.
This article summarises the first ICCMA held in 2015 (ICCMA’15). In this competition, solvers were invited to address standard decision and enumeration problems of abstract argumentation frameworks (Dunne and Wooldridge 2009).
Solvers’ performance is evaluated based on their time taken to provide a correct solution for a problem; incorrect results were discarded. More information about the competition, including complete results and benchmarks, can be found on the ICCMA website
Revision of abstract dialectical frameworks: Preliminary report
No full textAbstract Dialectical Frameworks (ADFs) enhance the capability of Dung´s argumentation frameworks by modelling relations between arguments in a flexible way, thus constituting a very general formalism for abstract argumentation. Since argumentation is
an inherently dynamic process, understanding how change in ADFs can be formalized is important. In this work we study AGM-style revision operators for ADFs by providing various representation results. We focus on the preferred semantics and employ tools recently developed in work on revision of Horn formulas as well as logic programs. Moreover, we present an alternative family of operators based on a variant of the postulates considering preferred interpretations of the original and admissible
interpretations of the revising ADF
On the relative expressiveness of argumentation frameworks, normal logic programs and abstract dialectical frameworks
No full textWe analyse the expressiveness of the two-valued semantics of abstract argumentation frameworks, normal logic programs and abstract dialectical frameworks. By expressiveness we mean the ability to encode a desired set of two-valued in-terpretations over a given propositional signature using only atoms from that signature. While the computational complex-ity of the two-valued model existence problem for all these languages is (almost) the same, we show that the languages form a neat hierarchy with respect to their expressiveness
Approximating Operators and Semantics for Abstract Dialectical Frameworks
No full textWe provide a systematic in-depth study of the semantics of abstract dialectical frameworks (ADFs), a recent generalisation of Dung\''s abstract argumentation frameworks. This is done by associating with an ADF its characteristic one-step consequence operator and defining various semantics for ADFs as different fixpoints of this operator. We first show that several existing semantical notions are faithfully captured by our definition, then proceed to define new ADF semantics and show that they are proper generalisations of existing argumentation semantics from the literature. Most remarkably, this operator-based approach allows us to compare ADFs to related nonmonotonic formalisms like Dung argumentation frameworks and propositional logic programs. We use polynomial, faithful and modular translations to relate the formalisms, and our results show that both abstract argumentation frameworks and abstract dialectical frameworks are at most as expressive as propositional normal logic programs
The Relative Expressiveness of Abstract Argumentation and Logic Programming
No full textWe analyze the relative expressiveness of the two-valued semantics of abstract argumentation frameworks, normal logic programs and abstract dialectical frameworks. By expressiveness we mean the ability to encode a desired set of two-valued interpretations over a given propositional vocabulary A using only atoms from A. While the computational complexity of the two-valued model existence problem for all these languages is (almost) the same, we show that the languages form a neat hierarchy with respect to their expressiveness. We then demonstrate that this hierarchy collapses once we allow to introduce a linear number of new vocabulary elements
Introducing the Second International Competition on Computational Models of Argumentation
No full textArgumentation is a major topic in the study of artificial intelligence. In particular, the problem of solving certain reasoning tasks of Dung´s abstract argumentation frameworks is central to many advanced argumentation systems. The fact that problems to be solved are mostly intractable requires efficient algorithms and solvers, that are to be evaluated on meaningful benchmarks. In this report, we introduce the Second International Competition on Computational Models of Argumentation (ICCMA´17), which is jointly organized by TU Dresden (Germany), TU Wien (Austria), and the University of Genoa (Italy), in affiliation with the 2017 International Workshop on Theory and Applications of Formal Argumentation (TAFA´17)
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