Improved Answer-Set Programming Encodings for Abstract Argumentation

The design of efficient solutions for abstract argumentation problems is a crucial step towards advanced argumentation systems. One of the most prominent approaches in the literature is to use Answer-Set Programming (ASP) for this endeavor. In this paper, we present new encodings for three prominent argumentation semantics using the concept of conditional literals in disjunctions as provided by the ASP-system clingo. Our new encodings are not only more succinct than previous versions, but also outperform them on standard benchmarks.Comment: To appear in Theory and Practice of Logic Programming (TPLP), Proceedings of ICLP 201

Foundations of implementations for formal argumentation

We survey the current state of the art of general techniques, as well as specific software systems for solving tasks in abstract argumentation frameworks, structured argumentation frameworks, and approaches for visualizing and analysing argumentation. Furthermore, we discuss challenges and promising techniques such as parallel processing and approximation approaches. Finally, we address the issue of evaluating software systems empirically with links to the International Competition on Computational Models of Argumentation

Foundations of Implementations for Formal Argumentation

This manuscript was published in IfCoLoG (ISBN 978-1-84890-253-4) and in the Handbook of Formal Argumentation (ISBN 978-1-84890-275-6).We survey the current state of the art of general techniques, as well as specific software systems for solving tasks in abstract argumentation frameworks, structured argumentation frameworks, and approaches for visualizing and analysing argumentation. Furthermore, we discuss challenges and promising techniques such as parallel processing and approximation approaches. Finally, we address the issue of evaluating software systems empirically with links to the International Competition on Computational Models of Argumentation.Austrian Science Funds (FWF)262327058

Abstract Argumentation in Dynamic Logic: Representation, Reasoning and Change

International Conference on Logic and Argumentation (CLAR 2018) - The paper benefited from several comments by Christoph Beierle after its presentation at KR 2014. After KR 2014, the ideas in the paper were presented in a workshop on argumentation in Lens in September 2015 and at the Cardiff Argumentation Forum in July 2016.International audienceWe provide a logical analysis of Dung’s abstract argumentation frameworks and their dynamics. We express attack relation and argument status by means of propositional variables and define acceptability criteria by formulas of propositional logic, which enables us to formulate the standard reasoning problems in logic. While the approaches in the literature express these problems as Boolean or quantified Boolean formulas, we here take advantage of a variant of Propositional Dynamic Logic PDL: Dynamic Logic of Propositional Assignments DL-PA, whose atomic programs are assignments of propositional variables to truth values. One of the benefits is that algorithms computing extensions of argumentation frameworks can be viewed as particular DL-PA programs. This allows us to formally prove the correctness of these algorithms. Another benefit is that in the same logic, we can also design and study programs which modify argumentation frameworks. Indeed, the basic operations on these propositional variables, viz. change of the truth values of the attack variables and the argument status variables, are nothing but atomic programs of DL-PA. We mainly focus on how the acceptance of one or more arguments can be enforced and show how this can be achieved by changing the truth values of the propositional variables describing the attack relation in a minimal way