Dissertations / Theses on the topic 'Representational Change Theory'

This thesis is about logical models of belief (and knowledge) representation and belief change. This means that we propose logical systems which are intended to represent how agents perceive a situation and reason about it, and how they update their beliefs about this situation when events occur. These agents can be machines, robots, human beings. . . but they are assumed to be somehow autonomous. The way a fixed situation is perceived by agents can be represented by statements about the agents� beliefs: for example �agent A believes that the door of the room is open� or �agent A believes that her colleague is busy this afternoon�. �Logical systems� means that agents can reason about the situation and their beliefs about it: if agent A believes that her colleague is busy this afternoon then agent A infers that he will not visit her this afternoon. We moreover often assume that our situations involve several agents which interact between each other. So these agents have beliefs about the situation (such as �the door is open�) but also about the other agents� beliefs: for example agent A might believe that agent B believes that the door is open. These kinds of beliefs are called higher-order beliefs. Epistemic logic [Hintikka, 1962; Fagin et al., 1995; Meyer and van der Hoek, 1995], the logic of belief and knowledge, can capture all these phenomena and will be our main starting point to model such fixed (�static�) situations. Uncertainty can of course be expressed by beliefs and knowledge: for example agent A being uncertain whether her colleague is busy this afternoon can be expressed by �agent A does not know whether her colleague is busy this afternoon�. But we sometimes need to enrich and refine the representation of uncertainty: for example, even if agent A does not know whether her colleague is busy this afternoon, she might consider it more probable that he is actually busy. So other logics have been developed to deal more adequately with the representation of uncertainty, such as probabilistic logic, fuzzy logic or possibilistic logic, and we will refer to some of them in this thesis (see [Halpern, 2003] for a survey on reasoning about uncertainty). But things become more complex when we introduce events and change in the picture. Issues arise even if we assume that there is a single agent. Indeed, if the incoming information conveyed by the event is coherent with the agent�s beliefs then the agent can just add it to her beliefs. But if the incoming information contradicts the agent�s beliefs then the agent has somehow to revise her beliefs, and as it turns out there is no obvious way to decide what should be her resulting beliefs. Solving this problem was the goal of the logic-based belief revision theory developed by Alchourrón, Gärdenfors and Makinson (to which we will refer by the term AGM) [Alchourrón et al., 1985; Gärdenfors, 1988; Gärdenfors and Rott, 1995]. Their idea is to introduce �rationality postulates� that specify which belief revision operations can be considered as being �rational� or reasonable, and then to propose specific revision operations that fulfill these postulates. However, AGM does not consider situations where the agent might also have some uncertainty about the incoming information: for example agent A might be uncertain due to some noise whether her colleague told her that he would visit her on Tuesday or on Thursday. In this thesis we also investigate this kind of phenomenon. Things are even more complex in a multi-agent setting because the way agents update their beliefs depends not only on their beliefs about the event itself but also on their beliefs about the way the other agents perceived the event (and so about the other agents� beliefs about the event). For example, during a private announcement of a piece of information to agent A the beliefs of the other agents actually do not change because they believe nothing is actually happening; but during a public announcement all the agents� beliefs might change because they all believe that an announcement has been made. Such kind of subtleties have been dealt with in a field called dynamic epistemic logic (Gerbrandy and Groeneveld, 1997; Baltag et al., 1998; van Ditmarsch et al., 2007b]. The idea is to represent by an event model how the event is perceived by the agents and then to define a formal update mechanism that specifies how the agents update their beliefs according to this event model and their previous representaton of the situation. Finally, the issues concerning belief revision that we raised in the single agent case are still present in the multi-agent case. So this thesis is more generally about information and information change. However, we will not deal with problems of how to store information in machines or how to actually communicate information. Such problems have been dealt with in information theory [Cover and Thomas, 1991] and Kolmogorov complexity theory [Li and Vitányi, 1993]. We will just assume that such mechanisms are already available and start our investigations from there. Studying and proposing logical models for belief change and belief representation has applications in several areas. First in artificial intelligence, where machines or robots need to have a formal representation of the surrounding world (which might involve other agents), and formal mechanisms to update this representation when they receive incoming information. Such formalisms are crucial if we want to design autonomous agents, able to act autonomously in the real world or in a virtual world (such as on the internet). Indeed, the representation of the surrounding world is essential for a robot in order to reason about the world, plan actions in order to achieve goals... and it must be able to update and revise its representation of the world itself in order to cope autonomously with unexpected events. Second in game theory (and consequently in economics), where we need to model games involving several agents (players) having beliefs about the game and about the other agents� beliefs (such as agent A believes that agent B has the ace of spade, or agent A believes that agent B believes that agent A has the ace of heart...), and how they update their representation of the game when events (such as showing privately a card or putting a card on the table) occur. Third in cognitive psychology, where we need to model as accurately as possible epistemic state of human agents and the dynamics of belief and knowledge in order to explain and describe cognitive processes. The thesis is organized as follows. In Chapter 2, we first recall epistemic logic. Then we observe that representing an epistemic situation involving several agents depends very much on the modeling point of view one takes. For example, in a poker game the representation of the game will be different depending on whether the modeler is a poker player playing in the game or the card dealer who knows exactly what the players� cards are. In this thesis, we will carefully distinguish these different modeling approaches and the. different kinds of formalisms they give rise to. In fact, the interpretation of a formalism relies quite a lot on the nature of these modeling points of view. Classically, in epistemic logic, the models built are supposed to be correct and represent the situation from an external and objective point of view. We call this modeling approach the perfect external approach. In Chapter 2, we study the modeling point of view of a particular modeler-agent involved in the situation with other agents (and so having a possibly erroneous perception of the situation). We call this modeling approach the internal approach. We propose a logical formalism based on epistemic logic that this agent uses to represent �for herself� the surrounding world. We then set some formal connections between the internal approach and the (perfect) external approach. Finally we axiomatize our logical formalism and show that the resulting logic is decidable. In Chapter 3, we first recall dynamic epistemic logic as viewed by Baltag, Moss and Solecki (to which we will refer by the term BMS). Then we study in which case seriality of the accessibility relations of epistemic models is preserved during an update, first for the full updated model and then for generated submodels of the full updated model. Finally, observing that the BMS formalism follows the (perfect) external approach, we propose an internal version of it, just as we proposed an internal version of epistemic logic in Chapter 2. In Chapter 4, we still follow the internal approach and study the particular case where the event is a private announcement. We first show, thanks to our study in Chapter 3, that in a multi-agent setting, expanding in the AGM style corresponds to performing a private announcement in the BMS style. This indicates that generalizing AGM belief revision theory to a multi-agent setting amounts to study private announcement. We then generalize the AGM representation theorems to the multi-agent case. Afterwards, in the spirit of the AGM approach, we go beyond the AGM postulates and investigate multi-agent rationality postulates specific to our multi-agent setting inspired from the fact that the kind of phenomenon we study is private announcement. Finally we provide an example of revision operation that we apply to a concrete example. In Chapter 5, we follow the (perfect) external approach and enrich the BMS formalism with probabilities. This enables us to provide a fined-grained account of how human agents interpret events involving uncertainty and how they revise their beliefs. Afterwards, we review different principles for the notion of knowledge that have been proposed in the literature and show how some principles that we argue to be reasonable ones can all be captured in our rich and expressive formalism. Finally, we extend our general formalism to a multi-agent setting. In Chapter 6, we still follow the (perfect) external approach and enrich our dynamic epistemic language with converse events. This language is interpreted on structures with accessibility relations for both beliefs and events, unlike the BMS formalism where events and beliefs are not on the same formal level. Then we propose principles relating events and beliefs and provide a complete characterization, which yields a new logic EDL. Finally, we show that BMS can be translated into our new logic EDL thanks to the converse operator: this device enables us to translate the structure of the event model directly within a particular axiomatization of EDL, without having to refer to a particular event model in the language (as done in BMS). In Chapter 7 we summarize our results and give an overview of remaining technical issues and some desiderata for future directions of research. Parts of this thesis are based on publication, but we emphasize that they have been entirely rewritten in order to make this thesis an integrated whole. Sections 4.2.2 and 4.3 of Chapter 4 are based on [Aucher, 2008]. Sections 5.2, 5.3 and 5.5 of Chapter 5 are based on [Aucher, 2007]. Chapter 6 is based on [Aucher and Herzig, 2007].

This study examines how adding avatars, personal visual representations of the user, on online forms impacts self-reported willingness for behavioral change, when considering health habits. Avatars are a gamification element proposed to have a positive impact on behavioral change. No earlier research has examined the distinction between the effects of the contemplation that occurs when acquiring an avatar and those of the actual avatar. This distinction was explored with a randomly controlled trial in the form of three questionnaires (pretest, self-reflection, posttest), distributed to a control group and an intervention group. 37 participants (20 women, 17 men, M = 33.4 years, age span 29–38 years) completed the study. The pretest consisted of questions about their current health situation, followed by the self-reflection task. The posttest measured the outcome variable: ”How willing are you to make a change in your everyday life in order to improve or maintain your general health?”. For the intervention group, the self- reflection and posttest were accompanied by an avatar. The results were analysed with a Mann- Whitney’s U-test, which showed that the avatar groups' self-reported willingness for behavioral change was higher compared to the control group. The effect was statistically significant. We discuss the applications and practical and ethical implications of avatars for increasing motivation. Further research should be done to replicate these findings to further examine the mechanics of the avatar representation.
Denna studie undersöker hur tillägget av avatarer, en personlig visuell representation av användaren, i webbformulär kan påverka självrapporterad villighet för beteendeförändring kopplat till hälsovanor. Avatarer är ett spelifieringselement som föreslås kunna ha en positiv påverkan på beteendeförändring. Ingen tidigare forskning har gjorts på distinktionen mellan effekter av självreflektion som sker vid förvärvandet av en avatar och den faktiska avataren. Den här distinktionen undersöktes genom en randomiserad kontrollerad studie i form av tre enkäter (förtest, självreflektion, eftertest) för en kontroll- och interventionsgrupp. 37 deltagare (20 kvinnor, 17 män, M = 33.4 år, åldersspann 29–38 år) slutförde studien. Förtestet bestod av frågor om deltagarnas nuvarande hälsa, följt av självreflektionen. Eftertestet innehöll utfallsmåttet: “Hur villig är du att göra en förändring i din vardag för att förbättra eller bibehålla din generella hälsa?”. För interventionsgruppen ackompanjerades självreflektionen och eftertestet av en avatar. Resultaten analyserades med ett Mann-Whitneys U-test, som visade att avatargruppens självskattade villighet för beteendeförändring var högre jämfört med kontrollgruppen. Effekten var statistiskt signifikant. Vi diskuterar tillämpningar samt praktiska och etiska implikationer av avatarer för att öka motivation. Vidare forskning bör göras för att replikera dessa fynd för att ytterligare undersöka mekaniken bakom avatar-representation.

In two studies, the author attempts to develop a general symbol theoretical approach to knowledge representation. The first study, Modeling change - the frame problem, critically examines the - so far unsuccessful - attempts to solve the notorious frame problem. By discussing and analyzing a number of related problems - the prediction problem, the revision problem, the qualification problem, and the book-keeping problem - the frame problem is distinguished as the problem of finding a representational form permitting a changing, complex world to be efficiently and adequately represented. This form, it is argued, is dictated by the metaphysics of the problem world, the fundamental form of the symbol system we humans use in rightly characterizing the world. In the second study, Pictures and words, the symbol theoretical approach is made more explicit. The subject Is the distinction between pictorial (non-linguistic, non-propositional, analogical, "direct") representation and verbal (linguistic, propositional) representation, and the further implications of this distinction. The study focuses on pictorial representation, which has received little attention compared to verbal representation. Observations, ideas, and theories in AI, cognitive psychology, and philosophy are critically examined. The general conclusion is that there is as yet no cogent and mature theory of pictorial representation that gives good support to computer applications. The philosophical symbol theory of Nelson Goodman is found to be the most thoroughly developed and most congenial with the aims and methods of AI. Goodman's theory of pictorial representation, however, in effect excludes computers from the use of pictures. In the final chapter, an attempt is made to develop Goodman's analysis of pictures further turning it into a theory useful to AI. The theory outlined builds on Goodman's concept of exemplification. The key idea is that a picture is a model of a description that has the depicted object as its standard model. One consequence Is that pictorial and verbal forms of representation are seen less as competing alternatives than as complementary forms of representation mutually supporting and depending on each other.
digitalisering@umu

This thesis inquires into the factors behind Hollywood's depiction of the Middle East. That depiction is not static, but is modified in response to changes in political events and US government foreign policy. Although the events of 9/11 seemed to justify the traditional negative stereotype of Arabs, the image has been partially and rationally re-interpreted. This was due to the rise in prominence of the ideas of a minority of radical and free-thinking members of the Hollywood community who embraced a more intellectual approach, which advocated that the popular Western view of the Arab world was unjustified and based on a fallacious fabrication for Western political advantage. The research further shows that these activists did not owe allegiance to the Hollywood-US government propaganda machine. They were able to fracture this traditional alliance and provide the opportunity for the appearance of films of a radical nature, which were critical of US Middle Eastern policy and projected the Arab world in a new light. The study analyzes a selection of films that represent the Middle East in terms of their philosophy and cinematic structure, which enables them to act as vectors to raise public awareness of the issues and to promote reconciliation and co-existence between East and West.

The thrust of this thesis is to describe base change BC_E/F at the level of chamber homology and K-theory for some p-adic groups, such as SL(2,F), GL(1,F) and GL(2,F). Here F is a non-archimedean local field and E is a Galois extension of F. We have had to master the representation theory of SL(2) and GL(2) including the Langlands parameters. The main result is an explicit computation of the effect of base change on the chamber homology groups, each of which is constructed from cycles. This will have an important connection with the Baum-Connes correspondence for such p-adic groups. This thesis involved the arithmetic of fields such as E and F, geometry of trees, the homology groups and the Weil group W_F.

214 pages
The Fock-Tani (unitary) transformation of the second- quantized Hamiltonian gives a representation which treats reactants and products symmetrically, and composites exactly. Each term in the Fock-Tani potential corresponds to a specific physical process and contains terms orthogonalizing continuum states to the bound states. The difficulty in carrying out this transformation can be lessened by working in a center of mass system, giving (n-1) reduced mass particles. After a general analysis of such systems, the Fock- Tani transformations in the 3→2-body case are carried out for the reactions a⁺+(b⁺c⁻)→(a⁺c⁻)+b⁺ and a⁻+(b⁺c⁻)→(a⁻b⁺)+c⁻. It is found that for (2) the transformation in the symmetrical reduced mass system can easily be carried out, but the Jacobi reduced mass system requires the more complicated d-matrix approach. This transformation has not yet been attempted in the full 3-body system but is likely to be as difficult as that for (1). First order differential and total cross sections are computed for resonant charge transfer in (1) for a proton- hydrogen initial state. The Fock-Tani T-matrix for the initial-state Jacobi system is found to be identical to that for the full 3-body system. That for the symmetrical reduced mass system gives an error of order l/mprot in the incident wave vector. A comparison of the Jacobi version and a previous special case Fock-Tani transformation, where the proton mass is taken as infinite, is also made. Cross sections for (ls→ls) positronium formation in positron-hydrogen collisions, calculated using the same program as for the proton-hydrogen case, are found to disagree with the previous Fock-Tani result, probably due to lack of convergence of the previous result. Cross sections for reactions (1) involving muons in hydrogenic isotopes (of interest in quantum electrodynamics and catalyzed fusion) are also calculated. Finally, extension of the results to higher order is considered. Polarized Schrodinger wave functions for a system containing a hydrogenic atom and a fully kinetic external charge are found to first order. These would be used in the Fock-Tani matrix elements to account for some initial- and final-state effects. Calculations of distorted second-quantized states and second and third order T-matrix elements are also outlined.

Cette recherche s’intéresse à l’efficacité des registres communicationnels actuels dans une perspective de mobilisation des consommateurs dans la sobriété carbone. Afin d’examiner l’efficacité de ces registres, quatre études ont été menées, i.e. une « méthode-Q » et trois expérimentations. Les deux premières études visent à explorer le rôle des représentations visuelles (i.e. images) et linguistiques (i.e. contenus sémantiques) utilisées pour désigner le changement climatique dans la transmission des préoccupations, des perceptions et des intentions envers la décarbonisation. La troisième étude cherche à expliquer l’effet de l’exploitation de la saillance de mortalité dans ces registres (i.e., anxiogènes vs. informatives) sur les choix de consommation pro-environnementaux (vs. pro-matérialistes). La dernière étude cherche à confirmer qu’une saillance de mortalité, quel que soit son origine (e.g. le changement climatique ou les attaques terroristes) est générateur en majorité des choix de consommation pro-matérialistes (vs. pro-environnementaux). En s’appuyant sur les résultats des ces études, nous mettons en lumière, tout d’abord, la nécessité de modifier ces registres afin de réduire leurs effets négatifs et/ou contreproductifs. Ensuite, la nécessité d’adopter une stratégie de segmentation de la communication selon la vision culturelle du monde dominante des individus pour les engager dans une lutte effective contre le changement climatique
This research focuses on the effectiveness of climate change communications in order to engage the consumer behaviour in carbon sobriety. To examine this effectiveness, four studies were carried out, i.e., a “Q-method” research and three experiments. The first two studies aim to explore the role of visual representation of climate change and semantic expressions, used to describe this phenomenon in conveying perceptions and attitudes towards decarbonisation. The third study aims to explain the impact of the type of communication (anxiety induced vs. informative) on consumption choices (pro-materialistic vs. pro-environmental). The last study seeks to confirm that mortality salience, whatever its origin is (e.g., climate change or terrorist attacks), generates mostly pro-materialistic consumption choices (vs. pro-environmental). Based on the results of these studies, we highlight, firstly, the necessity to modify these registers in order to reduce their negative and/or counterproductive effects. Secondly, the necessity to adopt a segmentation strategy of communication according to the cultural worldviews of individuals to engage them in an effective fight against the climate changes

Pour saisir l’importance et le champ d’action du hasard dans la poésie mallarméenne, nous allons procéder selon une démarche triple, recomposer l’histoire politique, poétique et philosophique qui a rendu possible l’apparition et l’instauration du hasard comme événement, à la fois révolutionnaire, créateur et conceptuel. À partir de Baudelaire, la poésie chante les révolutions échouées, mais pour maintenir vivant le désir d’un monde différent. Le hasard dans ce contexte est d’abord l’irruption imprévisible, fulgurante et éphémère d’un désir qui ne trouve pas un espace propre à l’intérieur de la vie sociale, Pour maintenir vivant et vivace le rêve d’un monde différent, la poésie doit : fournir la preuve que son action, tout en étant restreinte, compte ; faire durer un hasard voué à l’évanouissement, en constituant un espace où il puisse demeurer, se multiplier et ainsi retrouver la consistance qui le fera durer. Faire durer le hasard à l’origine de toute nouveauté, c’est la tâche que Mallarmé attribue à sa poésie. Sur le plan philosophique, cette démarche requiert une critique radicale de la raison et de la représentation. Dans ce contexte, Mallarmé a non seulement annoncé le hasard, mais il a cherché à découvrir la logique de ce qui échappe à la raison en composant une oeuvre capable de rendre réel, visible et intelligible, la puissance imprévisible et inépuisable que le hasard enserre
The purpose of this work is to comprehend the importance and scope of chance in the poetry of Mallarmé. In order to do that, we will proceed according to a three-pronged approach; recompose the political, poetic and philosophical context that made possible the emergence and establishment of chance as an event both revolutionary, creative and conceptual. Since Baudelaire, poetry sings the failed revolutions, but willing to preserve the desire for a different world. Chance in this context is the unpredictable bursts, lightning and transient of a desire that can not find its place within the social life, to keep alive and vivid the dream of a different world, poetry must: provide evidence that its action, even restricted, counts; make last chance doomed to fade, constituting a space where it can remain, multiply itself and thus find the consistency to remain. Prolonging a contingency that creates novelty is the task that Mallarmé attributes to his poetry. Philosophically, this approach requires a radical critique of reason and representation. In this context, Mallarmé has not only announced chance, but he sought to discover the logic of what escapes from reason composing a work capable of making real, visible and intelligible, the unpredictable and inexhaustible power that chance grips

This research into Chronic Fatigue Syndrome (CFS) presents the results of 60 first-person psycho-phenomenological interviews with 30 New Zealand women. The participants were recruited from the Canterbury and Wellington regions, 10 had recovered. Taking a non-dual, non-reductive embodied approach, the phenomenological data was analysed semiotically, using a graph-theoretical cluster analysis to elucidate the large number of resulting categories, and interpreted through the enactive approach to cognitive science. The initial result of the analysis is a comprehensive exploration of the experience of CFS which develops subject-specific categories of experience and explores the relation of the illness to universal categories of experience, including self, ‘energy’, action, and being-able-to-do. Transformations of the self surrounding being-able-to-do and not-being-able-to-do were shown to elucidate the illness process. It is proposed that the concept ‘energy’ in the participants’ discourse is equivalent to the Mahayana Buddhist concept of ‘contact’. This characterises CFS as a breakdown of contact. Narrative content from the recovered interviewees reflects a reestablishment of contact. The hypothesis that CFS is a disorder of action is investigated in detail. A general model for the phenomenology and functional architecture of action is proposed. This model is a recursive loop involving felt meaning, contact, action, and perception and appears to be phenomenologically supported. It is proposed that the CFS illness process is a dynamical decompensation of the subject’s action loop caused by a breakdown in the process of contact. On this basis, a new interpretation of neurological findings in relation to CFS becomes possible. A neurological phenomenon that correlates with the illness and involves a brain region that has a similar structure to the action model’s recursive loop is identified in previous research results and compared with the action model and the results of this research. This correspondence may identify the brain regions involved in the illness process, which may provide an objective diagnostic test for the condition and approaches to treatment. The implications of this model for cognitive science and CFS should be investigated through neurophenomenological research since the model stands to shed considerable light on the nature of consciousness, contact and agency. Phenomenologically based treatments are proposed, along with suggestions for future research on CFS. The research may clarify the diagnostic criteria for CFS and guide management and treatment programmes, particularly multidimensional and interdisciplinary approaches. Category theory is proposed as a foundation for a mathematisation of phenomenology.

With an exclusive focus on minority positions on climate change (CC), this dissertation examines the social and political debate happening on comment sections of CC-related articles from the Portuguese online newspapers Diário de Notícias and Observador. Motivated by the recent electoral successes in the European continent of far-right or populist political parties whose policy is associated with minority positions on CC, this study draws from theoretical frameworks engaged with cultural constructions of society and nature, as well as processes of meaning-making in self-other relations. It (1) analyzes in the comments how majority positions on CC are opposed and minority ones advanced when meanings clash, and (2) establishes how CC advocates are perceived and undermined by skeptics & contrarians. This dissertation analyses in detail insightful skeptical & contrarian comments paying attention to both content and form, namely by looking at polemic/dichotomized views seeking to reinforce skeptical & contrarian narratives, as well as at non-dichotomized ones where further dialogue is not inhibited. The results show that presently in the CC debate occurring in the press minority positions are to be found much more in comments than in published pieces. They also show how strict denial of anthropogenic CC is a rare occurrence among the comments reviewed, but that skepticism & contrarianism can manifest themselves in a variety of ways, and can assume many forms, including contestation of climate scientists, environmentalists and decision-makers, individually or as a group, whose calls-to-action elicit reactions of distrust, opposition, or conspiratorial ideas, depending on people’s worldviews. Contributing to the study of minority positions on CC, this dissertation provides further insight for science communication and policymaking into the role of people’s shared interpretative resources in the imagination and response to CC.
Com um foco exclusivo nas posições minoritárias sobre alterações climáticas (AC), esta dissertação examina o debate social e político que ocorre nas secções de comentários de artigos relacionados com as AC dos jornais portugueses online Diário de Notícias e Observador. Motivada pelos recentes sucessos eleitorais no continente europeu de partidos políticos de extrema-direita e populistas cujas políticas estão associadas a posições minoritárias sobre AC, este estudo parte de quadros teóricos dedicados às construções culturais da sociedade e da natureza, bem como aos processos de criação de significado em relações self-other. A dissertação (1) analisa nos comentários como as posições maioritárias sobre AC são opostas e as minoritárias avançadas quando os significados colidem, e (2) estabelece como os que defendem as AC são interpretados e comprometidos por céticos e contrários. Esta dissertação analisa em detalhe comentários céticos e contrários, prestando atenção tanto ao conteúdo como à forma, examinando as visões polémicas/dicotomizadas que procuram reforçar narrativas céticas e contrárias, bem como as não-dicotomizadas em que o diálogo não é restringido. Os resultados mostram que atualmente no debate sobre AC que ocorre nos jornais as posições minoritárias podem ser encontradas muito mais nos comentários do que nos artigos publicados. Eles também revelam que a negação estrita das AC antropogénicas é uma ocorrência rara entre os comentários analisados, mas que o ceticismo e contrarianismo podem manifestar-se de várias formas, incluindo a contestação de cientistas climáticos, ambientalistas e decisores, individualmente ou como um grupo, cujos apelos à ação suscitam reações de desconfiança, oposição, ou ideias conspiratórias, dependendo da visão de mundo das pessoas. Contribuindo para o estudo das posições minoritárias sobre as AC, esta dissertação oferece uma maior compreensão para a comunicação científica e a elaboração de políticas sobre o papel dos recursos interpretativos partilhados das pessoas na imaginação e resposta às AC.

Η Αλλαγή Πεποιθήσεων είναι το πεδίο που ασχολείται, μελετά και τυποποιεί ένα πλήθος διαδικασιών της συλλογιστικής σκέψης. Οι θεμελιώδεις αρχές της βρίσκονται σε διάφορα φιλοσοφικά συστήματα της περιόδου της αρχαιότητας. Ωστόσο, η σύγχρονη προβληματική που αναπτύσσεται γύρω από το πεδίο αυτό και που καλείται να αντιμετωπίσει εντάσσεται στην ευρύτερη περιοχή της Αναπαράστασης της Γνώσης. Στα μέσα της δεκαετίας του 80 και ύστερα από την προσπάθεια μετάβασης σε πιο συστηματικές και μαθηματικές προσεγγίσεις, η Αλλαγή Πεποιθήσεων αποκτά την τελική της μορφή. Ο όρος Αλλαγή διαιρείται σε τρεις ευρείες υπό-ενότητες: την πρόσθεση, την αφαίρεση και την αναθεώρηση. Η πρόσθεση αναφέρεται στη συλλογή νέων πληροφοριών (επέκταση πεποιθήσεων), η αφαίρεση την απώλεια πληροφορίας, ενώ η αναθεώρηση ερμηνεύει τη μερική ή ολική αλλαγή στο σύνολο των πεποιθήσεών μας, εξαιτίας της εμφάνισης μίας νέας πεποίθησης. Κάθε διαδικασία Αλλαγής συνοδεύεται από ένα σύνολο ορθολογικών αξιωμάτων. Τα αξιώματα διατυπώθηκαν με κύριο σκοπό την ομαδοποίηση, ταξινόμηση και περιορισμό των συλλογιστικών μας ενεργειών. Εκτός από τους τύπους αλλαγών και τα σύνολα των αξιωμάτων που αναφέρθηκαν στο χώρο της Αλλαγής Πεποιθήσεων υπάρχουν και άλλες σημαντικές - συμπληρωματικές διαδικασίες. Μία από τις πιο γνωστές και επωφελείς είναι αυτή της Επαναλαμβανόμενης Αναθεώρησης. Ενώ η απλή αναθεώρηση ερμηνεύει καταστάσεις που προξενούνται από την εμφάνιση μίας και μόνο πληροφορίας, η επαναλαμβανόμενη αναθεώρηση διασαφηνίζει περιπτώσεις μάθησης μέσα από το φάσμα των διαδοχικών πεποιθήσεων. Η παρούσα διατριβή θα μπορούσε να διαιρεθεί σε τρεις μεγάλες κατηγορίες. Η πρώτη εξετάζει συστηματικά τις διάφορες μεθόδους και τεχνικές που αναφέρονται στη διεθνή βιβλιογραφία. Η δεύτερη περιλαμβάνει την κυριότερη ερευνητική μας συνεισφορά καθώς και οι προτάσεις μας πάνω σε ανοικτά προβλήματα της Αλλαγής των Πεποιθήσεων. Πιο συγκεκριμένα, στο αρχικό στάδιο της έρευνάς μας αποτυπώνεται η προσπάθεια σύνδεσης της αναθεώρησης με την επαναλαμβανόμενη αναθεώρηση πεποιθήσεων. Η σύνδεση αυτή επιτυγχάνεται με την εισαγωγή ενός νέου αξιώματος που ονομάζουμε αξίωμα επαναλαμβανόμενης ανάκτησης. Αποδεικνύεται ότι το αξίωμα της επαναλαμβανόμενης ανάκτησης μπορεί να χρησιμοποιηθεί σε πολλές περιπτώσεις κατά τις οποίες το δεύτερο αξίωμα (DP2) των Darwiche και Pearl χαρακτηρίζεται αρκετά ισχυρό. Αποδεικνύουμε επίσης την ορθότητα και πληρότητα του παραπάνω αξιώματος μέσα από το σύστημα σφαιρών του Adam Grove. Στη συνέχεια η έρευνά μας στρέφεται στην προσπάθεια σύνδεσης δύο πολύ σημαντικών περιοχών στην αλλαγή πεποιθήσεων: την Επαναλαμβανόμενη και τη Relevance-Sensitive αναθεώρηση πεποιθήσεων. Τα αποτελέσματα της απόδειξης αφενός αποκαλύπτουν την ύπαρξη μη-συνέπειας μεταξύ τους αξιώματος (P) για τη Relevanse-Sensitive αναθεώρηση πεποιθήσεων με κάθε ένα από τα (DP) αξιώματα της επαναλαμβανόμενης αναθεώρησης πεποιθήσεων, αφετέρου αξιώνουν μία αναγκαία και γενικότερη αποκατάσταση στα τυπικά μοντέλα της αλλαγής πεποιθήσεων. Ακόμη μπορεί να αποδοθεί στη δική μας έρευνα και κάτι διαφορετικό, σε σχέση με τις άλλες: ότι η διαδικασία της αφαίρεσης πεποιθήσεων βασίζεται σε Horn Clauses. Ωστόσο, η αμιγής ερευνητική μας προσπάθεια αναφέρεται την παροχή σημασιολογίας βασιζόμενη σε διατάξεις πιθανών κόσμων για τη διαδικασία του e-contraction που εισήγαγε ο James Delgrande. Η Τρίτη κατηγορία, τέλος, αποβλέπει στην παρουσίαση της κλασσικής θεωρίας της Αναθεώρησης Πεποιθήσεων μέσα από την εφαρμογή της στην επιστήμη των υπολογιστών και πιο συγκεκριμένα, μέσω του Σημασιολογικού Ιστού.
Belief Change is an area that studies and standardizes several reasoning processes. However, the problems it has to confront rest in the wider area of Knowledge Representation. In the mid-1980s and after a transition effort to more systematic and mathematical Approaches, the Belief Change gets into its final form. The term “change” splits in three wide subgroups: expansion, contraction and revision. The expansion regards the collection of new information (belief expansion), while contraction concerns the loss of information. Finally, the revision explains the partial or total change in our beliefs, deriving from the appearance of new information. Every Change process is coupled with several rational postulates. Those were mainly formulated to group, classify and constrain our reasoning. Apart from the change formulas and the postulates mentioned above, in the field of Belief Change there are other important – additional processes. One of the most known and useful is the Iterated Revision. While the simple Revision explains conditions that are induced from the emergence of one and only information, the Iterated Revision clarifies cases of learning through the spectrum of successive beliefs. The present dissertation is classified in three major categories. The first one concerns the systematic study of several methods and techniques found in the international bibliography. The second incorporates our main contribution in research and our propositions with regard in open problems of the Belief Change. More specifically, the initial stage of our research is an effort to connect the revision with the iterated belief revision. This connection is achieved with the introduction of a new postulate called “iterated recovery postulate”. It is also established that the iterated recovery postulate (IR) can be used in many cases where the second postulate DP2, by Darwiche and Pearl, is qualified as rather strong. Moreover, we prove hereby that the postulate is sound and complete through the Adam Grove’s System of Spheres. Our research continues to connect two very important areas in the Belief Change: the Iterated and the Relevance-Sensitive belief revision. The conclusions of this proof reveal the inconsistency between the (P) postulate, regarding the Relevance-Sensitive belief revision, with “each and every one” of the DP postulates of the iterated belief revision. Likewise, they urge for a broad and imperative recovery of the “belief change” typical models. Unlike others, our contribution in research has to do with the belief contraction process, based on Horn Clauses. Our pure research regards the provision of semantics based on possible worlds orderings for the process of e-contraction, introduced by James Delgrande. Finally, the third category tries to present the classical theory of Belief Revision through its application in the computer science and specifically through the Semantic Web.