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

Multi-Context Reasoning in Continuous Data-Flow Environments

The field of artificial intelligence, research on knowledge representation and reasoning has originated a large variety of formats, languages, and formalisms. Over the decades many different tools emerged to use these underlying concepts. Each one has been designed with some specific application in mind and are even used nowadays, where the internet is seen as a service to be sufficient for the age of Industry 4.0 and the Internet of Things. In that vision of a connected world, with these many different formalisms and systems, a formal way to uniformly exchange information, such as knowledge and belief is imperative. That alone is not enough, because even more systems get integrated into the online world and nowadays we are confronted with a huge amount of continuously flowing data. Therefore a solution is needed to both, allowing the integration of information and dynamic reaction to the data which is provided in such continuous data-flow environments. This work aims to present a unique and novel pair of formalisms to tackle these two important needs by proposing an abstract and general solution. We introduce and discuss reactive Multi-Context Systems (rMCS), which allow one to utilise different knowledge representation formalisms, so-called contexts which are represented as an abstract logic framework, and exchange their beliefs through bridge rules with other contexts. These multiple contexts need to mutually agree on a common set of beliefs, an equilibrium of belief sets. While different Multi-Context Systems already exist, they are only solving this agreement problem once and are neither considering external data streams, nor are they reasoning continuously over time. rMCS will do this by adding means of reacting to input streams and allowing the bridge rules to reason with this new information. In addition we propose two different kind of bridge rules, declarative ones to find a mutual agreement and operational ones for adapting the current knowledge for future computations. The second framework is more abstract and allows computations to happen in an asynchronous way. These asynchronous Multi-Context Systems are aimed at modelling and describing communication between contexts, with different levels of self-management and centralised management of communication and computation. In this thesis rMCS will be analysed with respect to usability, consistency management, and computational complexity, while we will show how asynchronous Multi-Context Systems can be used to capture the asynchronous ideas and how to model an rMCS with it. Finally we will show how rMCSs are positioned in the current world of stream reasoning and that it can capture currently used technologies and therefore allows one to seamlessly connect different systems of these kinds with each other. Further on this also shows that rMCSs are expressive enough to simulate the mechanics used by these systems to compute the corresponding results on its own as an alternative to already existing ones. For asynchronous Multi-Context Systems, we will discuss how to use them and that they are a very versatile tool to describe communication and asynchronous computation

A Narrative Account of Argumentation

In this dissertation I attempt to accomplish three goals. The first goal is to develop a narrative account of argumentation. I show that storytelling serves as a legitimate mode of argumentation. I develop an account of narrative argument based on generalized features of narrative and a conception of argument that is rhetorical and in line with Charles Willards notion of argument as an interaction. I identify features of narrative argument that enable narrative to function as an argument and thus to provide reasons for a claim in the context of disagreement. As a result, I synthesize literatures on narrative and argumentation to provide a definition of narrative argument. The second goal of the dissertation is to argue for maintaining the narrative as a process without reconstructing the narrative into the dominant model of argument. In this part of the dissertation, I elaborate on the definition of narrative argument and argue that narrative argument must be understood as a process, and not as a product of argument. While the product view focuses on the form and structure of an argument as being linear, explicit, and containing premises and a conclusion, and treats arguments as things, the process view focuses on the whole act of arguing, thus highlighting the importance of the context of argumentation and the people involved. In support of this thesis, I show that reducing the narrative into premises and a conclusion is problematic because it deprives it of some of its persuasive force. Reducing the narrative into a product removes the real argumentpart of which is implicitfrom its context, its unique situation, and its complex social setting. The third goal of this dissertation is to develop an account of argument evaluation that is suitable for narrative argument understood as a process. I offer an account of how to evaluate narratives using the virtuous audience, combining theories of virtue argumentation and rhetorical audiences. In sum, this dissertation provides a definition of narrative argument, stipulates the conditions of narrative arguments that make them successful, and offers ways of evaluating the narrative while maintaining its form as a process

Elements for an Argumentative Method of Interpretation

When are we, in fact, arguing? Even one and the same author may offer more than one definition of what he understands by argumentation: this is partly because the problem of argumentation is not confined to a single area of knowledge or of practical life. Definitions of argumentation are as varied as the different positions taken on the question of what exactly we do when we argue. Be that as it may, we are struck by the fact that the problem of argumentation (above all in its application to hypothetic-inductive methods) has not been analysed as a problem linked to interpretation

Goals and functions of public argumentation

This position paper of Working Group 2 of the European Network for Argumentation and Public Policy Analysis (COST Action CA17132; https://publicpolicyargument.eu) reviews goals and functions of public argumentation. Drawing on a variety of disciplines, the paper introduces basic distinctions and charts out options. It is meant to guide reflection on the conceptual basis for the Action’s subsequent research regarding the analysis, evaluation, and design of public argumentation