Andrea Cohen

A survey of different approaches to support in argumentation systems

Fil: Cohen, Andrea. Universidad Nacional del Sur. Departamento de Ciencias e Ingenieria de la Computacion; Argentina. Consejo Nacional de Investigaciones Cientificas y Tecnicas; Argentina

An approach to abstract argumentation with recursive attack and support

This work introduces the Attack-Support Argumentation Framework (ASAF), an approach to abstract argumentation that allows for the representation and combination of attack and support relations. This framework extends the Argumen-tation Framework with Recursive Attacks (AFRA) in two ways. Firstly, it adds a support relation enabling to express support for arguments; this support can also be given to attacks, and to the support relation itself. Secondly, it extends AFRAs attack relation by allowing attacks to the aforementioned support relation. Moreover, since the support relation of the ASAF has a necessity interpretation, the ASAF also extends the Argumentation Framework with Necessities (AFN). Thus, the ASAF provides a unified framework for representing attack and support for arguments, as well as attack and support for the attack and support relations at any level.

Backing and undercutting in defeasible logic programming

Two important notions within the field of classical argumentation are undercutting defeaters and backings. The former represent an attack to an inference step, and the latter intend to provide defense against this type of attack. Defeasible Logic Programming (DELP) is a concrete argumentation system that allows to identify arguments whose conclusions or intermediate conclusions are in contradiction, capturing the notion of rebutting defeater. Nevertheless, in DELP is not possible to represent neither undercutting defeaters nor backings. The aim of this work is to extend the formalism of DELP to allow attack and support for defeasible rules. Thus, it will be possible to build arguments for representing undercutting defeaters and backings.

Extending DeLP with attack and support for defeasible rules

In several formalisms of classical argumentation two kinds of defeaters are considered: rebutting and undercutting. The former represents an attack to a conclusion and the latter an attack to an inference step. Defeasible Logic Programming (DeLP) is a formalism that combines argumentation and logic programming and provides a concrete argumentation system where arguments are built using program rules and facts. DeLP allows to identify arguments whose conclusions or intermediate conclusions are in contradiction. In that way, rebutting defeaters are captured. Nevertheless, in DeLP is not possible to represent an explicit attack to a program rule in order to capture undercutting defeaters. The contribution of this work is to extend the formalism of DeLP in order to allow the representation of both support and attack for defeasible rules. Therefore, it will be possible to build arguments that provide reasons for or against a defeasible rule and thus, undercutting defeaters and backings could be constructed.

A structured argumentation system with backing and undercutting

This work introduces Extended Defeasible Logic Programming (E-DeLP), a structured argumentation system enabling the expression of reasons for and against using defeasible rules. E-DeLPextends the formalism of Defeasible Logic Programming (DeLP) by incorporating two new kinds of rules: backing and undercutting rules. In that way, E-DeLPaccounts for Toulmins notion of backing and Pollocks notion of undercut, two important contributions within the field of argumentation. Thus, E-DeLPconstitutes a novel approach, being the first structured argumentation system in providing a unified setting for modeling Toulmins and Pollocks ideas simultaneously.

A characterization of types of support between structured arguments and their relationship with support in abstract argumentation

Abstract Argumentation is an important approach in artificial intelligence and multiagent systems, providing a basis for single agents to make rational decisions, and for groups of agents to reach agreements, as well as a mechanism to underpin a wide range of agent interactions. In such work, a crucial role is played by the notion of attack between arguments, and the notion of attack is well-studied. There is, for example, a range of different approaches to identifying which of a set of arguments should be accepted given the attacks between them. Less well studied is the notion of support between arguments, yet the idea that one argument may support another is very intuitive and seems particularly relevant in the area of decision-making where decision options may have multiple arguments for and against them. In the last decade, the study of support in argumentation has regained attention among researchers, but most approaches address support in the context of abstract argumentation where the elements from which arguments are composed are ignored. In contrast, this paper studies the notion of support between arguments in the context of structured argumentation systems where the elements from which arguments are composed play a crucial role. Different forms of support are presented, each of which takes into account the structure of arguments; and the relationships between these forms of support are studied. Then, the paper investigates whether there is a correspondence between the structured and abstract forms of support, and determines whether the abstract formalisms may be instantiated using concrete forms of support in terms of structured arguments. The conclusion is that support in structured argumentation does not mesh well with support in abstract argumentation, and this suggests that more work is required to develop forms of support in abstract argumentation that model what happens in structured argumentation.

Characterizing acceptability semantics of argumentation frameworks with recursive attack and support relations

Abstract Over the last decade, several extensions of Dungs Abstract Argumentation Frameworks (AFs) have been introduced in the literature. Some of these extensions concern the nature of the attack relation, such as the consideration of recursive attacks, whereas others incorporate additional interactions, such as a support relation. Recently, the Attack–Support Argumentation Framework (ASAF) was proposed, which accounts for recursive attacks and supports, attacks to supports and supports to attacks, at any level, where the support relation is interpreted as necessity. Currently, to determine the accepted elements of an ASAF (which may be arguments, attacks, and supports) it is required to translate such an ASAF into a Dungs AF. In this work, we provide a formal characterization of acceptability semantics directly on the ASAF, without requiring such a translation. We prove that our characterization is sound since it satisfies different results from Dungs argumentation theory; moreover, we formally show that the approach proposed here for addressing acceptability is equivalent to the preexisting one, in which the ASAF was translated into an AF. Also, we formalize the relationship between the ASAF and other frameworks on which it is inspired: the Argumentation Framework with Recursive Attacks (AFRA) and the Argumentation Framework with Necessities (AFN).

Argumentative AI Director Using Defeasible Logic Programming

In this work we present a novel implementation of an AI Director that uses argumentation techniques to decide dynamic adaptations in the level generation of a roguelike game called HermitArg. The architecture of the game introduces smart items with defeasible information to be analyzed in a dialectical process.