Advances in Abstract Argumentation - Expressiveness and Dynamics

Talk by Thomas Linsbichler

Location: APB 3027
Start: 27. July 2017 at 1:00 pm
End: 27. July 2017 at 2:00 pm
Research group: Computational Logic
Event series: KBS Seminar
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In recent years the research field of argumentation has become a major

topic in the study of artificial intelligence (AI). Within the argumentation process, the focus of this work is on the evaluation of the acceptability of conflicting arguments using the formal models of abstract argumentation frameworks (AFs) and abstract dialectical frameworks (ADFs). While an AF is a directed graph where nodes represent arguments and directed edges represent conflicts between arguments, ADFs constitute a very powerful generalization of AFs by additionally assigning to each argument an acceptance condition. In this work we contribute to the advancement of the study of abstract argumentation by addressing aspects of expressiveness and dynamics of argumentation semantics. In terms of expressiveness we complement recent work on realizability in AFs, investigate the role of rejected arguments, and study the induced class of compact argumentation frameworks. Then, we lift the study of expressiveness to the concept of input-output AFs. Finally, we present a unifying algorithmic approach to realizability capturing AFs and ADFs as well as intermediate formalisms in a modular way, which is also implemented in ASP. Taking into account the dynamic nature of argumentation, we study two central issues therein: revision and splitting. For revision we apply the seminal AGM theory of belief change to argumentation by presenting representation theorems for revision operators which guarantee to result in a single framework. We also present concrete belief change operators and analyze their computational complexity. Finally, we study splitting of ADFs, aiming for optimization of computation by incremental computation of

semantics.