Intuitions and the modelling of defeasible reasoning: some case studies

The purpose of this paper is to address some criticisms recently raised by John Horty in two articles against the validity of two commonly accepted defeasible reasoning patterns, viz. reinstatement and floating conclusions. I shall argue that Horty's counterexamples, although they significantly raise our understanding of these reasoning patterns, do not show their invalidity. Some of them reflect patterns which, if made explicit in the formalisation, avoid the unwanted inference without having to give up the criticised inference principles. Other examples seem to involve hidden assumptions about the specific problem which, if made explicit, are nothing but extra information that defeat the defeasible inference. These considerations will be put in a wider perspective by reflecting on the nature of defeasible reasoning principles as principles of justified acceptance rather than `real' logical inference.Comment: Proceedings of the 9th International Workshop on Non-Monotonic Reasoning (NMR'2002), Toulouse, France, April 19-21, 200

Online Handbook of Argumentation for AI: Volume 1

This volume contains revised versions of the papers selected for the first volume of the Online Handbook of Argumentation for AI (OHAAI). Previously, formal theories of argument and argument interaction have been proposed and studied, and this has led to the more recent study of computational models of argument. Argumentation, as a field within artificial intelligence (AI), is highly relevant for researchers interested in symbolic representations of knowledge and defeasible reasoning. The purpose of this handbook is to provide an open access and curated anthology for the argumentation research community. OHAAI is designed to serve as a research hub to keep track of the latest and upcoming PhD-driven research on the theory and application of argumentation in all areas related to AI.Comment: editor: Federico Castagna and Francesca Mosca and Jack Mumford and Stefan Sarkadi and Andreas Xydi

A Discussion Game for the Credulous Decision Problem of Abstract Dialectical Frameworks under Preferred Semantics

Abstract dialectical frameworks (ADFs) have been introduced as a general formalism for modeling and evaluating argumentation. However, the role of discussion in reasoning in ADFs has not been clarified well so far. The current work presents a discussion game, as a proof method, to answer credulous decision problems of ADFs under preferred semantics. The game can be the basis for an algorithm that can be used not only for answering the decision problem but also for human-machine interaction

A QBF-based Formalization of Abstract Argumentation Semantics

Supported by the National Research Fund, Luxembourg (LAAMI project) and by the Engineering and Physical Sciences Research Council (EPSRC, UK), grant ref. EP/J012084/1 (SAsSY project).Peer reviewedPostprin

On cumulativity in the context of defeasible argumentation

Las lógicas que permiten razonar de manera no-monótona suelen ser caracterizadas por la propiedad que carecen - casualmente, la monotonía - en vez de serlo por aquellas que sí gozan. Gabbay, Makinson y Kraus propusieron un conjunto de propiedades básicas de las relaciones de inferencia que toda teoría no-monótona debería satisfacer. No obstante, existen varios formalismos aparentemente razonables que no satisfacen algunos de estos principios, por caso la mayoría de los formalismos de argumentación rebatible. En este artículo determinamos el estado de estas propiedades básicas en el marco de dos populares sistemas argumentativosLogics for nonmonotonic reasoning have often been described by the property they lack—that is, monotonicity—instead of by those they do enjoy. Gabbay, Makinson and Kraus proposed a set of core properties for inference relations that every nonmonotonic theory ought to have. Yet, there are some apparently well-behaved formalisms that fail to comply with some of these principles, such as most defeasible argumentation formalisms. In this article we determine the status of these core properties in the context of two well-known argumentation frameworks.Workshop de Agentes y Sistemas Inteligentes (WASI)Red de Universidades con Carreras en Informática (RedUNCI