We study formal argumentation frameworks as introduced by Dung (1995). We show that any such argumentation framework can be syntactically augmented into a normal form (having a simplified attack relation), preserving the semantic properties of original arguments. An argumentation framework is in normal form if no argument attacks a conflicting pair of arguments. An augmentation of an argumentat...

Within the last decade, abstract argumentation has emerged as a central field in Artificial Intelligence. Besides providing a core formalism for many advanced argumentation systems, abstract argumentation has also served to capture several non-monotonic logics and other AI related principles. Although the idea of abstract argumentation is appealingly simple, several reasoning problems in this f...

This paper attempts to demonstrate the wide variety of characteristic properties of defeasible argumentation, of which nonmonotonicity is one. To do so, we introduce a simple formalism, called abstract argumentation system, with which we discuss different methods for raising arguments: forward reasoning, backward reasoning and, in particular, combinations thereof. Resource-bounded defeasible re...

In a complex, dynamic multi-agent setting, coherent team actions are often jeopardized by conflicts in agents’ beliefs, plans and actions. Despite the considerable progress in teamwork research, the challenge of intra-team conflict resolutionhas remained largely unaddressed. This paper presents CONSA, a system we are developing to resolve conflicts using argumentation-based negotiations. CONSA ...

The consideration of heterogenous knowledge sources for supporting decision making is key to accomplish informed decisions, e.g., about medical diagnosis. Consequently, merging different data from different knowledge bases is a key issue for providing support for decision-making. In this paper, we explore an argumentation context approach, which follows how medical professionals typically reaso...

Argumentation is a human-like reasoning mechanism contributing to the formalization of commonsense reasoning. In the last decade, several argument-based formalisms have emerged, with application in many areas, such as legal reasoning, autonomous agents and multi-agent systems; many are based on Dung’s seminal work characterizing Abstract Argumentation Frameworks (AF). Recent research in the are...

Argumentation is nowadays seen both as skill that people use in various aspects of their lives, as well as an educational technique that can support the transfer or creation of knowledge thus aiding in the development of other skills (e.g. Communication, critical thinking) or attitudes. However, teaching argumentation and teaching with argumentation is still a rare practice, mostly due to the l...

The goal of argumentation mining, an evolving research field in computational linguistics, is to design methods capable of analyzing people’s argumentation. In this article, we go beyond the state of the art in several ways. (i) We deal with actual Web data and take up the challenges given by the variety of registers, multiple domains, and unrestricted noisy user-generated Web discourse. (ii) W...

In this paper the authors develop a conceptual framework for appreciating the use of computer-supported argumentation systems in organisational settings undergoing strategic change. More specifically, the authors concentrate on the role of computer-supported argumentation as catalyst for compensating distortions in the outcome of change, originating from the organisation’s power regime. The fra...

We discuss argumentation frameworks with indirect attacks, such as why-questions and supports. A whyquestion is regarded as a kind of attack relation, and a support is an answer to an un-presented why-question. Based on this idea, we construct an argumentation framework with why-questions from a pair of knowledge bases, as an instantiation of Dung’s abstract argumentation framework, and show th...