A Brief Introduction to Formal Argumentation Theory

Presented by Martin Caminada

Formal argumentation theory has developed into a popular paradigm for shaping multi-agent systems, both for supporting an agent’s individual reasoning capabilities and for enabling various forms of inter-agent communication. In the current tutorial, we provide an overview of some of the key concepts in formal argumentation theory. On the highest level of abstraction, we describe the notion of an argumentation framework and show how it can be evaluated using argumentation semantics, both in its extensions and labellings form. Subsequently, we zoom in on the structure of the arguments: a defeasible derivation consisting of different types of inference rules. We then examine some of the properties that concrete argumentation formalisms aim to satisfy, as well as some of the techniques to bring this about. Two concrete argumentation formalisms (ASPIC+ and ABA) are examined in detail, with emphasis on both their strengths and weaknesses. We then turn our attention to algorithms and proof procedures, the perspective being global (determine all acceptable arguments and conclusions) and local (determine the acceptance status of an individual argument or conclusion). It is then examined how the dialectical proof procedures of the local perspective can be used as the basis for agent communication protocols, in which one agent aims to convince another agent of what to do or what to believe, using interactive discussion. Apart from the theory, we also show demonstrations of some of the current implementations of argument-based discussion protocols, and provide links to the source code, enabling participants to apply these in their own software developments.

Topics

  • abstract argumentation
  • argumentation semantics (extensions + labellings)
  • rule-based argumentation
  • rationality postulates
  • ASPIC+ and ABA (assumption-based argumentation) algorithms and proof procedures
  • argument-based agent communication protocols implementations