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Together with an basic assumption of the main thesis of the theory of singular direct reference, this paper formulates two original theses grounded in the Kripkean notion of proper names. Regarding the assumption of the main thesis, efforts have been made to explicitly explain its essence as a reactionary theory against the description theory of proper names, a theory mainly due to Bertrand Russells (1905) influential article "On Denoting". Grounded in Russell, outlining the fundamental idea of proper names as abbreviated or disguised definite descriptions, this paper moves forward through the critiques of Strawsons (1950) "On Referring", Donnellans (1966) "Reference and Definite Descriptions" and Kripkes (1977) "Speaker's Reference and Semantic Reference". With the historical background in place, in accordance with Salmons (1982) "Reference & Essence" the arguments against the theory of descriptions for proper names are put forward, which leads to the assumption of the mentioned main thesis. Regarding the papers more original theses, the first of these distinguishes between different kinds of proper names depending on whether or not they refer to an object capable of cognitive functioning. The main thrust of this paper is however made through the formulation of the second thesis, as it is being aimed at challenging Kripke's Millian notion of all proper names as being non-connoting. However, in contrast to this view in accordance with the view being put forward in this paper, cognition-referring proper names are connoting. Additionally, a finishing discussion is supplemented concluding descriptions of such connotations as being questions for pragmatism.

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[pt] Em métodos formais, uma das abordagens que vem obtendo sucesso nos últimos anos é a de verificação formal. Dentro desta, vem se destacando uma técnica chamada de verificação de modelos (model checking), na qual se verifica automaticamente a validade de propriedades em sistemas acerca do funcionamento de um sistema. Atualmente, a verificação de modelos é muito empregada em informática na verficação formal de software e hardware, mas tem sido utilizada em outra áreas, como em matemática e em economia. Esta dissertação visa aplicar verificação de modelos a problemas de economia. O tema da pesquisa seria delimitado à Teoria dos Jogos. Algumas inadequações foram observadas, fazendo-se necessário algumas novas definições: uma definição de qualitativa que se utiliza de uma linguagem lógica denominada de Game Analysis Logic (GAL); uma linguagem para descrever jogo denominada de RollGame (Romero - All Game); uma tradução de RollGame na linguagem de especificação de modelos; uma tradução da definição de jogo em estrutura de Kripke. Observou-se ainda que com a utilização de model checking em jogos consegue- se analisar estratégias de jogadores. Uma ferramenta para automatizar a tradução de RollGame em model checking foi desenvolvida, chamada de StratAn-RollGame (Strategy Analyzed using RollGame). Assim, a presente dissertação demonstrou que de fato é possível utilizar verificação de modelos em outras areas. / [en] In formal methods, one of the approaches that have been successful lately is Model Checking, which consists in a technique to achieve automatic verification about a system behavior. Nowadays, the model checking is very frequently employed in computer science to formal verification of software and hardware, but it is not used in other knowledge fields, such as mathematics and economics. The purpose of this research is to apply model checking in economics problems, using Game Theory. Some inadequacies have been observed. Therefore, it is necessary to create new definitions: a generic and qualitative definition of game that uses one logic language called Game Analysis Logic (GAL); a new language to describe game called RollGame (Romero + All Game); a translation from RollGame to a language of model specification; a translation from game definition to Kripke structure. It is also been observed that the use of model checking makes it possible to analyze players strategies. One tool, called StratAn-RollGame (Strategy Analyzed using RollGame), makes the translation from RollGame to model Checking automatic. Thus, the present research has demonstrated that is possible indeed to use model checking in other knowledge fields.

This dissertation is focused on an algebraic approach of some many-valued generalizations of modal logics. The starting point is the definition of the [0,1]-valued and the Ł_n-valued Kripke models, where [0,1] denotes the well known MV-algebra and Ł_n its finite subalgebra {0, 1/n, ... , (n-1)/n,1} for any positive integer n. Two types of structures are used to define validity of formulas: the class of L-frames and the class of Ł_n-valued L-frames. The latter structures are L-frames in which we specify in each world u the set Ł_m (where m is a divisor of n) of the possible truth values of the formulas in u. These two classes of structures define two distinct notions of validity. We use these notions to study the problem of definability of classes of structures with modal formulas. We obtain for these two classes an equivalent of the Goldblatt-Thomason theorem. We are able to consider completeness problems with respect to these relational semantics thanks to the connections between relational and algebraic semantics. Our strongest results are about Ł_n-valued logics. We are indeed able to apply and develop algebraic tools (namely, canonical and strong canonical extensions) that allow to generate complete Ł_n-valued logics. / Nous consacrons cette dissertation à une étude algébrique de certaines généralisations multivaluées des logiques modales. Notre point de départ est la définition des modèle de Kripke [0,1]-valués et Ł_n-valués, où [0,1] désigne la MV-algèbre bien connue et Ł_n sa sous-algèbre {0, 1/n, ... , (n-1)/n,1} pour tout naturel non nul n. Nous utilisons deux types de structures pour définir une relation de validité: la classe des L-structures et celles des L-structures Ł_n-valuées. Ces dernières sont des L-structures dans lesquelles nous précisons pour chaque monde u l'ensemble Ł_m (où m est un diviseur de n) des valeurs de vérité que les formules sont autorisées à prendre en u. Ces deux classes de structures définissent deux notions distinctes de validité. Nous les utilisons pour étudier le problème de la définissabilité des classes de structures à l'aide du langage modal. Nous obtenons dans les deux cas l'équivalent du théorème de Goldblatt-Thomason. Nous considérons aussi les problèmes de complétude vis-à-vis de ces sémantiques relationnelles à l'aide des liens qui les lient à la sémantique algébrique. Les résultats les plus forts que nous obtenons concernent les logiques modales Ł_n-valuées. En effet, dans ce cas, nous pouvons appliquer et développer des outils algébriques (à savoir, les extensions canoniques et les extensions canoniques fortes) qui permettent de générer des logiques complètes.

This essay investigates Haukioja's (2010) notion of actuality-dependence. This notion is an attempt to explain the rigid behaviour of some kind terms; in particular natural kind terms like “water” and “tiger”. A definition of rigidity for kind terms has to take in account speakers' semantic intentions. This, together with the fact that actuality-dependence can only be applied successfully to a kind term if the members of its extension all share an underlying, non-trivial property, makes the notion of actuality-dependence face the problem of reference failures. A speaker's intention for a certain term to be actuality-dependent might fail, in the sense that the members of the kind picked out by the term in question lack underlying properties of the right sort. Three ways to solve this issue are shown to be unsatisfactory, ultimately leading to the conclusion that actuality-dependence cannot be the semantic feature that single out natural kind terms as semantically special.

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Dans le domaine de la modélisation du raisonnement, plusieurs approches se basent sur les logiques modales qui permettent de formaliser le raisonnement sur des éléments non factuels, comme la croyance, le savoir ou encore la nécessité. Une extension pondérées de ces logiques modales permet de moduler les éléments non factuels qu'elle décrit. En particulier, nous nous intéressons à l'extension pondérée des logiques modales qui permet de formaliser des croyances graduelles : nous traitons des aspects sémantiques et axiomatiques ainsi que des aspects syntaxiques liés à la manipulations de telles croyances modulées. Ainsi, les travaux de cette thèse sont organisés en trois parties. Nous proposons, d'une part, une sémantique proportionnelle qui étend la sémantique de Kripke classiquement utilisée pour les logiques modales ; ainsi qu'une étude des axiomes modaux dans le contexte de cette sémantique des modalités pondérées. D'autre part, nous proposons un modèle ensembliste flou pour représenter et manipuler des degrés de croyances. Enfin, nous mettons en œuvre ces modèles théoriques dans deux applications : un outil de vérification de formules modales pondérées et un joueur artificiel pour le jeu coopératif Hanabi dont la prise de décision repose sur un raisonnement sur ses propres croyances. / In the field of reasoning models, many approaches are based on modal logics, which allow to formalise the non-factual reasoning, as belief, knowledge or necessity reasoning. A weighted extension for these modal logics aims at modulating the considered non-factual elements. In particular, we examine the weighted extension of modal logics for graded beliefs: we study their semantical and axiomatical issues related to manipulating such modulated beliefs. Therefore, this thesis works are organised in three parts. We first propose a proportional semantics which extends the Kripke semantics, classically used for modal logics. We also study modal axioms regarding the proposed semantics. Then, we propose a fuzzy set model for representing and manipulating belief degrees. We finally use these two formal models in two different applications: a model checking tool for weighted modal formulae and an artifical player for a cooperative game called Hanabi in which decision making is based on graded belief reasoning.

Thesis (MSc)--Stellenbosch University, 2012. / ENGLISH ABSTRACT: Truth preservation is an important topic in model theory. However a brief examination of the models for a logic often show that isomorphism is needlessly restrictive as a truth preserving construction. In the case of modal logics with Kripke semantics the notions of simulation and bisimulation prove far more practical and interesting than isomorphism. We present and study these various notions, followed by a discussion of Shehtman’s frame product as semantics for certain many-dimensional modal logics. We show how simulations and bisimulations can be interpreted inside models over frame products. This is followed by a discussion on a category-theoretic setting for frame products, where the arrows may run between frames with different types. / AFRIKAANSE OPSOMMING: Die behou van waarheid is ’n prominente onderwerp in modelteorie. ’n Vlugtige ondersoek van die modelle vir ’n besondere logika wys egter dat isomorfisme onnodig beperkend as waarheid-behoudende konstruksie is. In die geval van modale logika met Kripke se semantiek is simulasie en bisimulasie heelwat meer prakties en interessant as isomorfisme. Na die bekendstel en studie van hierdie onderskeie begrippe bespreek ons Shehtman se raamproduk as semantiek vir sekere meer-dimensionele modale logikas. Ons wys ons hoe simulasies en bisimulasies binne modelle oor sulke raamprodukte geïnterpreteer kan word. Daarna bespreek ons ’n kategorie-teoretiese konteks vir raamprodukte, waar die pyle tussen rame met verskillende tipes mag loop.

This thesis describes a decision and minimization procedure for modal logic. The decision procedure answers the question of whether there exists a satisfying pointed model for a formula which obeys user-specified first-order conditions on the underlying frame. Then the minimization procedure produces a minimal model with respect to the number of worlds that satisfies the desired formula while obeying the requisite conditions on the underlying frame. A proof of correctness for the decision and minimization procedures is supplied, as well as a description of an implementation built upon the Enfragmo model expansion solver. / Graduate / 0984 / 0318 / wbkboyer@gmail.com