Automata for infinite argumentation structures

The theory of abstract argumentation frameworks (afs) has, in the main, focused on finite structures, though there are many significant contexts where argumentation can be regarded as a process involving infinite objects. To address this limitation, in this paper we propose a novel approach for describing infinite afs using tools from formal language theory. In particular, the possibly infinite set of arguments is specified through the language recognized by a deterministic finite automaton while a suitable formalism, called attack expression, is introduced to describe the relation of attack between arguments. The proposed approach is shown to satisfy some desirable properties which cannot be achieved through other “naive” uses of formal languages. In particular, the approach is shown to be expressive enough to capture (besides any arbitrary finite structure) a large variety of infinite afs including two major examples from previous literature and two sample cases from the domains of multi-agent negotiation and ambient intelligence. On the computational side, we show that several decision and construction problems which are known to be polynomial time solvable in finite afs are decidable in the context of the proposed formalism and we provide the relevant algorithms. Moreover we obtain additional results concerning the case of finitaryafs

Technological roadmap on AI planning and scheduling

At the beginning of the new century, Information Technologies had become basic and indispensable constituents of the production and preparation processes for all kinds of goods and services and with that are largely influencing both the working and private life of nearly every citizen. This development will continue and even further grow with the continually increasing use of the Internet in production, business, science, education, and everyday societal and private undertaking. Recent years have shown, however, that a dramatic enhancement of software capabilities is required, when aiming to continuously provide advanced and competitive products and services in all these fast developing sectors. It includes the development of intelligent systems – systems that are more autonomous, flexible, and robust than today’s conventional software. Intelligent Planning and Scheduling is a key enabling technology for intelligent systems. It has been developed and matured over the last three decades and has successfully been employed for a variety of applications in commerce, industry, education, medicine, public transport, defense, and government. This document reviews the state-of-the-art in key application and technical areas of Intelligent Planning and Scheduling. It identifies the most important research, development, and technology transfer efforts required in the coming 3 to 10 years and shows the way forward to meet these challenges in the short-, medium- and longer-term future. The roadmap has been developed under the regime of PLANET – the European Network of Excellence in AI Planning. This network, established by the European Commission in 1998, is the co-ordinating framework for research, development, and technology transfer in the field of Intelligent Planning and Scheduling in Europe. A large number of people have contributed to this document including the members of PLANET non- European international experts, and a number of independent expert peer reviewers. All of them are acknowledged in a separate section of this document. Intelligent Planning and Scheduling is a far-reaching technology. Accepting the challenges and progressing along the directions pointed out in this roadmap will enable a new generation of intelligent application systems in a wide variety of industrial, commercial, public, and private sectors

SCC-recursiveness: a general schema for argumentation semantics

AbstractIn argumentation theory, Dung's abstract framework provides a unifying view of several alternative semantics based on the notion of extension. In this context, we propose a general recursive schema for argumentation semantics, based on decomposition along the strongly connected components of the argumentation framework. We introduce the fundamental notion of SCC-recursiveness and we show that all Dung's admissibility-based semantics are SCC-recursive, and therefore a special case of our schema. On these grounds, we argue that the concept of SCC-recursiveness plays a fundamental role in the study and definition of argumentation semantics. In particular, the space of SCC-recursive semantics provides an ideal basis for the investigation of new proposals: starting from the analysis of several examples where Dung's preferred semantics gives rise to questionable results, we introduce four novel SCC-recursive semantics, able to overcome the limitations of preferred semantics, while differing in other respects

Dialogue, argumentation, and belief revision: a study of apologetic conversations in West Cameroon

This work studies dialogue, argumentation, and their relationship to belief revision in person-to-person apologetics in five West Cameroonian dialogues. The seeming irrelevance of Western Apologetics to West Cameroonian thought is the problem that stimulated the study. The primary methodological steps of the study include obtaining meticulously transcribed scripts of unrehearsed conversations, and subjecting those transcripts to an inquiry about the presence and nature of dialogue, argument patterns, commitment, questions, rhetoric, and belief revision in the conversations. These primary tools are drawn from Commitment in Dialogue (1995), Argumentation Schemes (2008), ‘A Truth Maintenance System’ (1979), ‘Reason Maintenance and Belief Revision’ (1992), and related sources. The initial premise, to be tested by the research, is that these conversational elements are present, and that the theories are useful in understanding the dialogues’ rationality. The second, but no less important, premise of the study is that this research contributes to an understanding of the nature and role of the cumulative case in the practice of person-to-person apologetics in West Cameroon and cultural situations dominated by relativism. Chapter 1 introduces the background of the research and the questions of the inquiry, which I call ‘tools’. Chapter 2 questions the significance of the tools and the analysis of the data for person-to-person apologetics in pluralistic contexts. Chapters 3-7 document the analysis of the dialogues. And chapter 8 ends with a summary of the evidence for the thesis of the work: ‘A belief’s entrenchment, the result of argument patterns converging into a cumulative case for the belief, is primarily sensitive to understanding and revision in the context of dialogue.’ This work contributes to the understanding of modern African rationality, and the relationships of dialogue, argument, belief revision, and the cumulative case in relativistic contexts

Ponderação e proporcionalidade: uma teoria analítica do raciocínio constitucional

A presente tese procede ao estudo teórico dos conceitos jurídicos da ponderação e da proporcionalidade. Para esse efeito, são individuados e qualificados normativamente cada um desses conceitos, são identificadas as respectivas condições de relevância normativa, e são apuradas as relações conceptuais que os conectam. Em concreto, após a enunciação das respectivas pressuposições teóricas — designadamente, o reconhecimento da derrotabilidade como propriedade definitória das normas jurídicas — e das respectivas condições de relevância jurídica — designadamente, a verificação de conflitos normativos irresolúveis intra-sistemicamente, como amiúde sucede com os conflitos com normas constitucionais atributivas de direitos e liberdades fundamentais —, formula-se uma teoria geral acerca da ponderação enquanto operação intelectual de estabelecimento autónomo de preferências normativas, no âmbito da qual se explora o discurso das razões para a acção como elemento decisivo para a justificação dos juízos ponderativos. Em função da relação que a une à operação ponderativa, é também exaurida a estrutura e comportamento da norma da proporcionalidade, sendo ainda autonomizada a operação de segunda ordem da pesagem, que responde particularisticamente às propriedades dos casos concretos e é indispensável para a justificação dos valores a atribuir às intensidades das restrições a direitos fundamentais. No contexto da análise da proporcionalidade, é ainda analisada e rejeitada a existência de um autónomo princípio da proibição da insuficiência aplicável aos direitos positivos, como é também estudada a possibilidade de deferência judicial no quadro regulativo que a proporcionalidade empresta aos juízos ponderativos. Por tomar o domínio constitucional como base de trabalho e por se inserir na tradição da filosofia analítica, a tese acaba por consubstanciar, mais genericamente, uma teoria analítica do raciocínio constitucional.This PhD thesis aims at the theoretical study of the legal concepts of balancing and proportionality. For that purpose, each of these concepts is identified and normatively qualified, the respective conditions of normative relevance are made explicit, and the conceptual relationships connecting them are ascertained. Specifically, after the enunciation of the respective theoretical presuppositions—namely, the recognition of defeasibility as a defining property of legal norms—and of the respective conditions of legal relevance—namely, the verification of irresolvable intra-systemic normative conflicts, as often happens with conflicts with constitutional norms attributing fundamental rights and freedoms—, it is articulated a general theory of balancing as an intellectual operation of autonomous establishment of normative preferences, in the context of which the discourse of reasons for action is explored as a decisive element for the justification of balancing judgements. Due to the relationship that links it to the balancing operation, the structure and behaviour of the proportionality norm is also fully examined; and it is autonomized a second-order operation of weighing, which responds particularistically to the properties of concrete cases and is indispensable for the justification of the values to be attributed to the intensities of the restrictions to fundamental rights. In the context of the analysis of proportionality, the existence of an autonomous principle of the prohibition of insufficiency of action applicable to positive rights is also studied and rejected, as is the possibility of judicial deference in the regulatory framework that proportionality lends to balancing judgements. By taking the constitutional domain as a working basis and by inserting itself in the tradition of analytical philosophy, the thesis ends up consubstantiating, more generally, an analytical theory of constitutional reasoning

Perceiving and Reasoning about a Changing World

A rational agent (artificial or otherwise) residing in a complex changing environment must gather information perceptually, update that information as the world changes, and combine that information with causal information to reason about the changing world. Using the system of defeasible reasoning that is incorporated into the OSCAR architecture for rational agents, a set of reason-schemas is proposed for enabling an agent to perform some of the requisite reasoning. Along the way, solutions are proposed for the Frame Problem, the Qualification Problem, and the Ramification Problem. The principles and reasoning described have all been implemented in OSCAR