Diego C. Martínez

Progressive defeat paths in abstract argumentation frameworks

Abstract argumentation systems are formalisms for defeasible reasoning where some components remain unspecified, the structure of arguments being the main abstraction. In the dialectical process carried out to identify accepted arguments in the system some controversial situations may appear. These relate to the reintroduction of arguments into the process which cause the onset of circularity. This must be avoided in order to prevent an infinite analysis. Some systems apply the sole restriction of not allowing the introduction of previously considered arguments in an argumentation line. However, repeating an argument is not the only possible cause for the risk mentioned. A more specific restriction needs to be applied considering the existence of subarguments. In this work, we introduce an extended argumentation framework where two kinds of defeat relation are present, and a definition for progressive defeat path.

Acceptability in Timed Frameworks with Intermittent Arguments

In this work we formalize a natural expansion of timed argumentation frameworks by considering arguments that are available with (possibly) some repeated interruptions in time, called intermittent arguments. This framework is used as a modelization of argumentation dynamics. The notion of acceptability of arguments is analyzed as the framework evolves through time, and an algorithm for computing intervals of argument defense is introduced.

Stable extensions in timed argumentation frameworks

A Timed Abstract Argumentation Framework is a novel formalism where arguments are only valid for consideration in a given period of time, which is defined for every individual argument. Thus, the attainability of attacks and defenses is related to time, and the outcome of the framework may vary accordingly. In this work we study the notion of stable extensions applied to timed-arguments. The framework is extended to include intermittent arguments, which are available with some repeated interruptions in time.

On defense strength of blocking defeaters in admissible sets

Extended argumentation framework is a formalism where defeat relations are determined by establishing a preference between arguments involved in symmetric conflicts. This process possibly leads to blocking situations, where conflicting arguments are found to be incomparable or equivalent in strength. In this work we introduce new argumentation semantics for extended frameworks, by taking into account the strength of an argument defense. Each of these new admissibility notions relies on the presence of blocking defeaters as argument defenders.

Bipolarity in temporal argumentation frameworks

A Timed Argumentation Framework (TAF) is a formalism where arguments are only valid for consideration during specific intervals of time, called availability intervals, which are defined for every individual argument. The original proposal is based on a single abstract notion of attack between arguments that remains static and permanent in time. Thus, in general, when identifying the set of acceptable arguments, the outcome associated with a TAF will vary over time.Here, we are introducing an extension of TAF adding the capability of modeling a support relation between arguments. In this sense, the resulting framework provides a suitable model for different time-dependent issues; thus, the main contribution of this work is to provide an enhanced framework for modeling a positive (support) and negative (attack) interaction which varies over time, features that are highly relevant in many real-world situations. This addition leads to a Timed Bipolar Argumentation Framework (T-BAF), where classical argument extensions can be defined, aiming at advancing in the integration of temporal argumentation in different application domains. Bipolar frameworks are equipped with temporal availability for arguments.Admissibility-based extensions for timed argumentation are characterized.Several relations between semantics in timed argumentation are presented.Relations between the classic bipolar and extension-based semantics are studied for BAFs.

An Approach to Characterize Topic-Centered Argumentation

As we engage in a debate with other parties, it is usual that several subjects might come under discussion. In this work, we propose an extension of classic abstract argumentation frameworks which includes a set of interrelated topics decorating arguments. These topics represent what the arguments are addressing and provide a supporting structure for the analysis of multi-topic argumentation. A notion of “proximity” of an argument to the focus of the debate is introduced, leading to a notion of distance between the topics of the arguments, which is used for proximity-based semantic elaborations.

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.

A Petri Net Model of Argumentation Dynamics

Petri nets are a mathematical modelling tool suitable for describing dynamic computational systems. In this work we present a formalization of abstract argumentation frameworks using Petri nets, where arguments and attacks are represented as places and transitions. This provides a formalism to study the semantic consequences of a procedural evaluation of argument attacks. The relation between markings of the net and argument extensions is analysed.