Argumentation Systems (Computer Science)

Misyurov D.A. Dialectical formulas based on the binary notation as the development formulas // Credo New. 2012. №2

by Dmitry Misyurov

The article suggests dialectical formulas based on the binary notation as the development formulas: formula with... more The article suggests dialectical formulas based on the binary notation as the development formulas: formula with dominant and the non-dominant elements; universal formula; formula with symbolic weight of elements; tautological formula. For example, it suggests an opportunity to use the dialectical formulas for modeling and artificial intelligence creation, etc.

Argumentation support: from technologies to tools

by Mark Aakhus

Moor, A. D., & Aakhus, M. (2003). Argumentation support: from technologies to tools. In H. Weigand, G. Goldkuhl, & A. de Moor (Eds.), Proceedings of the 8th International Working Conference on the Language-Action Perspective on Communication Modelling (Vol. 49, pp. 93-98). Tilburg, The Netherlands: Working Conference on the Language Action Perspective.

A revised and updated version was published as:

Moor, A. de, & Aakhus, M. (2006). Argumentation Support: From technologies to tools. Communications of the ACM, 49(3), 93-98.

Electronic argumentation support is increasingly important in today’s networked society. Virtual research... more Electronic argumentation support is increasingly important in today’s networked society. Virtual research collaboration, e-business, and many other domains of professional life critically depend on adequate support of tools for productive argumentative interactions. However, a plethora of technologies exist that are not necessarily tools. A technology only is a tool if it serves the purposes of the community in which it is used. In this paper, we outline an approach to diagnose to what extent a particular argumentation technology is a tool. We do this by combining a socio- technical view on technologies with a pragma-dialectical approach to argumentation analysis. We argue that for technologies to become a tool, argumentation routines and design need to co-evolve. We illustrate our approach by applying it to a case on group report authoring.

Semi-Stable Semantics

by Martin Caminada

Martin Caminada, Walter Carnielli and Paul Dunne
Journal of Logic and Computation (in print)

In this paper, we examine an argument-based semantics called semi-stable semantics. Semi-stable semantics is quite... more In this paper, we examine an argument-based semantics called semi-stable semantics. Semi-stable semantics is quite close to traditional stable semantics in the sense that every stable extension is also a semi-stable extension. One of the advantages of semi-stable semantics is that for finite argumentation frameworks there always exists at least one semi-stable extension. Furthermore, if there also exists at least one stable extension, then the semi-stable extensions coincide with the stable extensions. Semi-stable semantics can be seen as a general approach that can be applied to abstract argumentation, as well as to fields like default logic and answer set programming, yielding an interpretation with properties very similar to those of paraconsistent logic, including the properties of crash resistance and backward compatibility.

A Labelling-Based Justification Status of Arguments

by Martin Caminada

Yining Wu and Martin Caminada
Studies in Locic 3(4):12-29 (2010)

In this paper, we define a labelling-based justification status of the arguments in an argumentation framework. Our... more In this paper, we define a labelling-based justification status of the arguments in an argumentation framework. Our proposal allows for a more fine-grained notion of a justification status than the traditional extensions-based approaches. In particular, we are able to distinguish different levels at which an argument can be accepted or rejected. Our approach is fully compatible with traditional abstract argumentation in the sense that it works on standard argumentation frameworks and can be implemented using existing argumentation-based proof procedures.

An Introduction to Argumentation Semantics

by Martin Caminada

Pietro Baroni, Martin Caminada and Massimiliano Giacomin
The Knowledge Engineering Review (in print)

This paper presents an overview on the state of the art of semantics for abstract argumentation, covering both some of... more This paper presents an overview on the state of the art of semantics for abstract argumentation, covering both some of the most influential literature proposals and some general issues concerning semantics definition and evaluation. As to the former point the paper reviews Dung’s original notions of complete, grounded, preferred, and stable semantics, as well as subsequently proposed notions like semi-stable, ideal, stage, and CF2 semantics, considering both the extension-based and the labelling-based approaches with respect to their definitions. As to the latter point the paper presents an extensive set of general properties for semantics evaluation and analyzes the notions of argument justification and skepticism. The final part of the paper is devoted to discuss some relationships between semantics properties and domain specific requirements.

On the Limitations of Abstract Argumentation

by Martin Caminada

Martin Caminada and Yining Wu
BNAIC 2011

In the current paper we re-examine the three-step procedure with respect to argumentation for inference. It is... more In the current paper we re-examine the three-step procedure with respect to argumentation for inference. It is observed that when viewing the argumentation process in a holistic way, one encounters several problems that tend to be overlooked when restricting oneself to pure abstract argumentation. We describe three such problems, which have to do with the interaction between abstract argumentation and instantiated (structured) arguments. We argue that these problems are related to fundamental limitations in the approach of abstract argumentation.

Manipulation in Group Argument Evaluation

by Martin Caminada

Martin Caminada, Gabriella Pigozzi and Mikołaj Podlaszewski
IJCAI 2011, pages 121-126

Given an argumentation framework and a group of agents, the individuals may have divergent opinions on the status of... more Given an argumentation framework and a group of agents, the individuals may have divergent opinions on the status of the arguments. If the group needs to reach a common position on the argumentation framework, the question is how the individual evaluations can be mapped into a collective one. This problem has been recently investigated by Caminada and Pigozzi. In this paper, we investigate the behaviour of two of such operators from a social choice-theoretic point of view. In particular, we study under which conditions these operators are Pareto optimal and whether they are manipulable.

An Axiomatic Account of Formal Argumentation

by Martin Caminada

Martin Caminada and Leila Amgoud
AAAI 2005, pages 608-613

Argumentation theory has become an important topic in the field of AI. The basic idea is to construct arguments in... more Argumentation theory has become an important topic in the field of AI. The basic idea is to construct arguments in favor and against a statement, to select the “acceptable” ones and, finally, to determine whether the statement can be accepted or not. Dung’s elegant account of abstract argumentation (Dung 1995) may have caused some to believe that defining an argumentation formalism is simply a matter of determining how arguments and their defeat relation can be constructed from a given knowledge base. Unfortunately, things are not that simple; many straightforward instantiations of Dung’s theory can lead to very unintuitive results, as is discussed in this paper. In order to avoid such anomalies, in this paper we are interested in defining some rules, called rationality postulates or axioms, that govern the well definition of an argumentation system. In particular, we define two important rationality postulates that any system should satisfy: the consistency and the closedness of the results returned by that system. We then provide a relatively easy way in which these quality postulates can be warranted by our argumentation system.

An Algorithm for Stage Semantics

by Martin Caminada

In the current paper, we re-examine the concept of stage semantics, which is one of the oldest semantics for abstract... more In the current paper, we re-examine the concept of stage semantics, which is one of the oldest semantics for abstract argumentation. Using a formal treatment of its properties, we explain how the intuition behind stage semantics differs from the intuition behind the admissibility based semantics that most scholars in argumentation theory are familiar with. We then provide a labelling-based algorithm for computing all stage extensions, based on earlier algorithms for computing all preferred, stable and semi-stable extensions.

On the Formalization Socratic Dialogue

by Martin Caminada

In many types of natural dialogue it is possible that one of the
participants is more or less forced by the... more In many types of natural dialogue it is possible that one of the
participants is more or less forced by the other participant towards making commitments. This force usually comes in the form of sharp questions that guide a participant into a specific direction (like a contradiction). Examples of such dialogues occur in the philosophy of Socrates, critical interviews and the cross­examination of witnesses in court. In the current paper, we examine the characteristics of these kinds of dialogues, and provide a first sketch of how they could be formalized.

A Formal Account of Socratic-Style Argumentation

by Martin Caminada

In traditional mathematical models of argumentation an argument often consists of a chain of rules or reasons,... more In traditional mathematical models of argumentation an argument often consists of a chain of rules or reasons, beginning with premisses and leading to a conclusion that is endorsed by the party that put forward the argument. In informal reasoning, however, one often encounters a specific class of counterarguments that until now has received little attention in argumentation formalisms. The idea is that instead of starting with the premisses, the argument starts with the propositions put forward by the counterparty, of which the absurdity is illustrated by showing their (defeasible) consequences. This way of argumentation (which we call S-arguments) is very akin to Socratic dialogues and critical interviews; it also has applications in modern philosophy. In this paper, various examples of S-arguments are provided, as well as a treatment of the problems that occur when trying to formalize them
in existing formalisms. We also provide general guidelines that can serve as a basis for implementing S-arguments into various existing formalisms. In particular, we show how S-arguments can be implemented in Pollock’s formalism, how they fit
into Dung’s abstract argumentation approach and how they are related to the issue of self-defeating arguments.

An Implementation of Basic Argumentation Components

by Martin Caminada

The current implementation provides a demonstration of a number of basic argumentation components that can be applied... more The current implementation provides a demonstration of a number of basic argumentation components that can be applied in the context of multi-agent systems. These components include algorithms for calculating argumentation semantics, as well as for determining the justification status of the arguments and providing explanation in the form of formal discussion games. Furthermore, the current demonstrator also includes the first implementation we know of regarding argument-based judgment aggregation theory.

Towards and Argument Game for Stable Semantics

by Martin Caminada

This is a preliminary version of a later publication in the Logical Journal of IGPL. Readers are advised to read the latter version instead.

In this paper, we present a discussion game for argumentation under stable semantics. Our work is inspired by... more In this paper, we present a discussion game for argumentation under stable semantics. Our work is inspired by Vreeswijk and Prakken, who have defined a similar game for preferred semantics. In the current paper, we restate Vreeswijk and Prakken’s work using the approach of argument labellings and then show how it can be adjusted for stable semantics. The nature of the resulting argument game is somewhat unusual, since stable semantics does not satisfy the property of relevance.

An Implementation of Argument Based Discussion

by Martin Caminada

This demonstrator is superseded by the work of Mikolaj Podlaszewski for COMMA 2010 and AAMAS 2011.

With the current demonstrator, we present an implementation of formal argumentation that is not only able to evaluate... more With the current demonstrator, we present an implementation of formal argumentation that is not only able to evaluate an argument according st standard argumentation semantics, but is also able to engage in a discussion to defend its answer. This discussion is formal yet natural enough to be applicable in agent-to-agent as well as in agent-to-human settings.

Comparing Two Unique Extension Semantics for Formal Argumentation: Ideal and Eager

by Martin Caminada

In formal argumentation, grounded semantics is well known for yielding exactly one unique extension. Since grounded... more In formal argumentation, grounded semantics is well known for yielding exactly one unique extension. Since grounded semantics has a very sceptical nature, one can ask the question whether it is possible to define a unique extension semantics that is more credulous. Recent work of Dung, Mancarella and Toni proposes what they call ideal semantics, which is a unique extension semantics that is more credulous than grounded semantics. In the current paper, we define a unique extension semantics called eager semantics that is even more credulous than ideal semantics. We then examine how this semantics relates to the existing argumentation semantics proposed by Dung and others.

Collapse In Formal Argumentation Systems

by Martin Caminada

This is a technical report that contains the proofs of the associated BNAIC paper.

Over the last decennia, many systems for formal argumentation have been defined. The problem, however, is that these... more Over the last decennia, many systems for formal argumentation have been defined. The problem, however, is that these systems do not always satisfy reasonable properties. In this paper, we focus on the particular property that a conflict between two arguments cannot keep other unrelated arguments from becoming justified. Although this property appears obvious,
it is in fact violated by several existing argumentation formalisms. In this paper we examine what exactly goes wrong and how things can be improved.

A Gentle Introduction to Argumentation Semantics

by Martin Caminada

This document presents an overview of some of the standard semantics for formal argumentation, including Dung’s... more This document presents an overview of some of the standard semantics for formal argumentation, including Dung’s notions of grounded, preferred, complete and stable semantics, as well as newer notions like Caminada’s semi-stable semantics and Dung,
Mancarella and Toni’s ideal semantics. These semantics will be treated both in their original extension-based form, as well as in the form of argument labellings. Our treatment includes a sketch of few algorithms for skeptical as well as for the credulous approach to argumentation.

On the Issue of Contraposition of Defeasible Rules

by Martin Caminada

The past ten years have shown a great variety of approaches for formal argumentation. An interesting question is to... more The past ten years have shown a great variety of approaches for formal argumentation. An interesting question is to which extent these various formalisms correspond to the different application domains. That is, does the appropriate argumentation formalism depend on the particular domain of application, or does “one size fits all”. In this paper, we study this question from the perspective of one relatively simple design consideration: should or should there not be contrapostion of (or modus tollens) on defeasible rules. We aim to show that the answer depends on whether one is considering epistemical or constitutive reasoning, and that hence different domains require fundamentally different forms of defeasible reasoning.

Complete Extensions In Argumentation Coincide With 3-Valued Stable Models In Logic Programming

by Martin Caminada

In this paper, we prove the correspondence between complete extensions in abstract argumentation and 3-valued stable... more In this paper, we prove the correspondence between complete extensions in abstract argumentation and 3-valued stable models in logic programming. This result is in line with earlier work of [6] that identified the correspondence between the grounded extension in abstract argumentation and the well-founded model in logic programming, as well as between the stable extensions in abstract argumentation and the stable models in logic programming.

On Judgment Aggregation In Abstract Argumentation

by Martin Caminada

Judgment aggregation is a field in which individuals are required to vote for or against a certain decision (the... more Judgment aggregation is a field in which individuals are required to vote for or against a certain decision (the conclusion) while providing reasons for their choice. The reasons and the conclusion are logically connected propositions. The problem is how a collective judgment on logically interconnected propositions can be defined from individual judgments on the same propositions. It turns out that, despite the fact that the individuals are logically consistent, the aggregation of their judgments may lead to an inconsistent group outcome, where the reasons do not support the conclusion. However, in this paper we claim that collective irrationality should not be the only worry of judgment aggregation. For example, judgment aggregation would not reject a consistent combination of reasons and conclusion that no member voted for. In our view this may not be a desirable solution. This motivates our research about when a social outcome is ‘compatible’ with the individuals’ judgments. The key notion that we want to capture is that any individual member has to be able to defend the collective decision. This is guaranteed when the group outcome is compatible with its members views. Judgment aggregation problems are usually studied using classical propositional logic. However, for our analysis we use an argumentation approach to judgment aggregation problems. Indeed the question of how individual evaluations can be combined into a collective one can also be addressed in abstract argumentation. We introduce three aggregation operators that satisfy the condition above, and we offer two definitions of compatibility. Not only does our proposal satisfy a good number of standard judgment aggregation postulates, but it also avoids the problem of individual members of a group having to become committed to a group judgment that is in conflict with their own individual positions.