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Estudo sobre a Demonstração do segundo teorema de incompletude de Gödel

Estivalet, Manuel Bauer
Fonte: Universidade Federal do Rio Grande do Sul Publicador: Universidade Federal do Rio Grande do Sul
Tipo: Dissertação Formato: application/pdf
POR
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A presente dissertação consiste em um estudo de apresentações da demonstração do Segundo Teorema de Incompletude de Gödel. Considera, com especial atenção, aquelas feitas por Shoefield no Mathematical Logic e por Hilbert e Bernays no Grundlagen der Mathematik. Como resultado, obtém-se uma análise das condições de derivabilidade e considerações sobre como é possível demonstrá-las.

Godel type solution in teleparallel gravity

Obukhov, Y. N.; Vargas, T.
Fonte: Elsevier B.V. Publicador: Elsevier B.V.
Tipo: Artigo de Revista Científica Formato: 365-373
ENG
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The stationary cosmological model without closed timelike curves of Godel type is obtained for the ideal dust matter source within the framework of the teleparallel gravity. For a specific choice of the teleparallel gravity parameters, this solution reproduces the causality violating stationary Godel solution in general relativity, in accordance with the teleparallel equivalent of general relativity. The relation between the axial-vector torsion and the cosmic vorticity is clarified. (C) 2004 Elsevier B.V. All rights reserved.

Gödel e Einstein: e quando o tempo não resiste à amizade?

Dahmen,Sílvio R.
Fonte: Sociedade Brasileira de Física Publicador: Sociedade Brasileira de Física
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/01/2006 PT
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Algumas amizades resistem ao teste do tempo. Mas o que dizer quando o próprio tempo não resiste a uma amizade? Em 1949 Kurt Gödel publicou um artigo no qual apresentava uma solução exata das equações de Einstein - que veio a ser conhecida como Universo de Gödel - na qual era possível, ao menos teoricamente, viajar no tempo. Neste artigo discuto as implicacões Físicas e filosóficas deste importante trabalho bem como o caráter da fecunda amizade entre Gödel e Einstein.

Are the Gödel incompleteness theorems limitative results for the neurosciences?

Buechner, Jeff
Fonte: Springer Netherlands Publicador: Springer Netherlands
Tipo: Artigo de Revista Científica
EN
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There are many kinds of limitative results in the sciences, some of which are philosophical. I am interested in examining one kind of limitative result in the neurosciences that is mathematical—a result secured by the Gödel incompleteness theorems. I will view the incompleteness theorems as independence results, develop a connection with independence results in set theory, and then argue that work in the neurosciences (as well as in molecular, systems and synthetic biology) may well avoid these mathematical limitative results. In showing this, I argue that demonstrating that one cannot avoid them is a computational task that is beyond the computational capacities of finitary minds. Along the way, I reformulate three philosophical claims about the nature of consciousness in terms of the Gödel incompleteness theorems and argue that these precise reformulations of the claims can be disarmed.

Intencionalidade e inteligência artificial no pensamento de Dennett; Intentionality and artificial intelligence in Dennett’s thought

Santos, Guilherme Silveira de Almeida
Fonte: Universidade Federal de Goiás; Brasil; UFG; Programa de Pós-graduação em Filosofia (FAFIL); Faculdade de Filosofia - FAFIL (RG) Publicador: Universidade Federal de Goiás; Brasil; UFG; Programa de Pós-graduação em Filosofia (FAFIL); Faculdade de Filosofia - FAFIL (RG)
Tipo: Dissertação Formato: application/pdf
POR
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The concept of intentional stance, a very important concept of Daniel Dennett’s philosophical thought, is a central aspect to a naturalized viewpoint of intentionality. There are three levels to predicting the behavior of an object: 1) The physical stance, at this level, the prediction is based on the physical properties or physical laws. 2) The design stance, at this level, the prediction is based on the function of an object. 3) The intentional stance, at this level, the object is considered a intentional agent, that has belief, thinking and intention. More over, from Dennett’s point of view, the naturalization of intentionality is the way to the possibility of construction of computers that will have intentional behavior. Also, the development of intelligent computers is the objective of Artificial Intelligence (AI) research. And also, is important to show the refutations of two skeptical arguments that try to prove the impossibility of machines intentionality. Two arguments against some aspects of AI research are the Gödel’s theorem argument and the chinese room argument. The objective of dissertation is show that the concept pf intentional stance is a possibility to construction of artificial intentional agents.; O conceito de postura intencional...

Os trabalhos de Gödel e as denominadas ciências exatas: em homenagem ao centenário do nascimento de Kurt Gödel

D'Alkaine,C.V.
Fonte: Sociedade Brasileira de Física Publicador: Sociedade Brasileira de Física
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/01/2006 PT
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Após uma breve resenha da vida de Gödel, assinalando as origens de suas tradições intelectuais, são analisados o seu teorema da completude, o seu trabalho de tese, o teorema da incompletude e o teorema sobre a impossibilidade de demonstrar a consistência de sistemas formais complexos dentro do mesmo sistema formal. A seguir, são discutidas suas contribuições à independência da Hipótese do Contínuo e do Axioma de Escolha dos outros axiomas da teoria dos conjuntos. Nesse contexto são finalmente discutidas algumas idéias em relação à pequena influência que as contribuições de Gödel, para descrever alguns dos limites do pensamento racional, têm tido nas assim chamadas ciências exatas ou naturais, especialmente, Física e Química. Algumas reflexões são, nesse sentido, propostas.

Godel-type space-time metrics

Romano, Antonio Enea; Goebel, Charles
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Relevância na Pesquisa
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A simple group theoretic derivation is given of the family of space-time metrics with isometry group SO(2,1) X SO(2) X R first described by Godel, of which the Godel stationary cosmological solution is the member with a perfect-fluid stress-energy tensor. Other members of the family are shown to be interpretable as cosmological solutions with a electrically charged perfect fluid and a magnetic field.; Comment: Heavly rewritten respect to the orginal version, corrected some typos due to files transfer in the last submitted version

N=2 supergravity in three dimensions and its Godel supersymmetric background

Banados, Maximo; Faraggi, Alberto T.; Theisen, Stefan
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Relevância na Pesquisa
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The four dimensional Godel spacetime is known to have the structure M_3 x R. It is also known that the three-dimensional factor M_3 is an exact solution of three-dimensional gravity coupled to a Maxwell-Chern-Simons theory. We build in this paper a N=2 supergravity extension for this action and prove that the Godel background preserves half of all supersymmetries.

The genetic code Via Godel encoding

Negadi, Tidjani
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Publicado em 06/05/2008
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The genetic code structure into distinct multiplet-classes as well as the numeric degeneracies of the latter are revealed by a two-step process. First, an empirical inventory of the degeneracies (of the shuffled multiplets) in two specific equal moieties of the experimental genetic code table is made and transcribed in the form of a sequence of integers. Second, a Godel Encoding procedure is applied to the latter sequence delivering, as an output, a Godel Number the digits of which, from the decimal representation, could remarkably describe the amino acids and the stops and allow us also to compute the exact degeneracies, class by class. The standard and the vertebrate mitochondrial genetic codes are considered and their multiplet structure is fully established.

On the D-brane solutions in Godel Universe

Panigrahi, Kamal L.; Swain, Pratap K.
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Relevância na Pesquisa
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We present a class of supersymmetric Godel solutions in string theory from the non-standard intersection of branes in supergravities. Such solutions are obtained by applying a T-duality on the known solutions in PP-wave spacetime. We further present classical solutions of supersymmetric D-brane in Godel universes arising from the PP-wave in the near horizon geometry of stack of D5-branes and from the new isometries of H_6 PP-wave background. These branes are supported by multiple constant Neveu-Schwarz and Ramond-Ramond field strengths.; Comment: 10 pages, typos fixed, added references

Over-Rotating Black Holes, Godel Holography and the Hypertube

Gimon, Eric G.; Horava, Petr
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Publicado em 03/05/2004
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We demonstrate how a five dimensional Godel universe appears as the core of resolved two-charge and three-charge over-rotating BMPV black holes. A smeared generalized supertube acts as a domain wall and removes regions of closed timelike curves by cutting off both the inside and outside solution before causality violations appear, effectively allowing the Godel universe and the over-rotating black hole to solve each other's causality problems. This mechanism suggests a novel form of holography between the compact Godel region and the diverse vacua and excitations of the bound state of a finite number of D0 and D4-branes with fundamental strings.; Comment: 34 pages

General Non-extremal Rotating Charged Godel Black Holes in Minimal Five-Dimensional Gauged Supergravity

Wu, Shuang-Qing
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Relevância na Pesquisa
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We present the general exact solutions for non-extremal rotating charged black holes in the Godel universe of five-dimensional minimal supergravity theory. They are uniquely characterized by four non-trivial parameters, namely the mass $m$, the charge $q$, the Kerr equal rotation parameter $a$, and the Godel parameter $j$. We calculate the conserved energy, angular momenta and charge for the solutions and show that they completely satisfy the first law of black hole thermodynamics. We also study the symmetry and separability of the Hamilton-Jacobi and the massive Klein-Gordon equations in these Einstein-Maxwell-Chern-Simons-Godel black hole backgrounds.; Comment: 4 pages, revtex4.cls. 4th revised version

Godel-Type Metrics in Various Dimensions

Gurses, M.; Karasu, A.; Sarioglu, O.
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Relevância na Pesquisa
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Godel-type metrics are introduced and used in producing charged dust solutions in various dimensions. The key ingredient is a (D-1)-dimensional Riemannian geometry which is then employed in constructing solutions to the Einstein-Maxwell field equations with a dust distribution in D dimensions. The only essential field equation in the procedure turns out to be the source-free Maxwell's equation in the relevant background. Similarly the geodesics of this type of metric are described by the Lorentz force equation for a charged particle in the lower dimensional geometry. It is explicitly shown with several examples that Godel-type metrics can be used in obtaining exact solutions to various supergravity theories and in constructing spacetimes that contain both closed timelike and closed null curves and that contain neither of these. Among the solutions that can be established using non-flat backgrounds, such as the Tangherlini metrics in (D-1)-dimensions, there exists a class which can be interpreted as describing black-hole-type objects in a Godel-like universe.; Comment: REVTeX4, 19 pp., no figures, improved and shortened version, note the slight change in the title [accepted for publication in Classical and Quantum Gravity]

Dynamics and stability of the Godel universe

Barrow, John D.; Tsagas, Christos G.
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Relevância na Pesquisa
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We use covariant techniques to describe the properties of the Godel universe and then consider its linear response to a variety of perturbations. Against matter aggregations, we find that the stability of the Godel model depends primarily upon the presence of gradients in the centrifugal energy, and secondarily on the equation of state of the fluid. The latter dictates the behaviour of the model when dealing with homogeneous perturbations. The vorticity of the perturbed Godel model is found to evolve as in almost-FRW spacetimes, with some additional directional effects due to shape distortions. We also consider gravitational-wave perturbations by investigating the evolution of the magnetic Weyl component. This tensor obeys a simple plane-wave equation, which argues for the neutral stability of the Godel model against linear gravity-wave distortions. The implications of the background rotation for scalar-field Godel cosmologies are also discussed.; Comment: Revised version, to match paper published in Class. Quantum Grav

Godel brane

Barrow, John D.; Tsagas, Christos G.
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Relevância na Pesquisa
27.73%
We consider the brane-world generalisation of the Godel universe and analyse its dynamical interaction with the bulk. The exact homogeneity of the standard Godel spacetime no longer holds, unless the bulk is also static. We show how the anisotropy of the Godel-type brane is dictated by that of the bulk and find that the converse is also true. This determines the precise evolution of the nonlocal anisotropic stresses, without any phenomenological assumptions, and leads to a self-consistent closed set of equations for the evolution of the Godel brane. We also examine the causality of the Godel brane and show that the presence of the bulk cannot prevent the appearance of closed timelike curves.; Comment: Revised version, to match paper published in Phys. Rev. D

The Kerr-Newman-Godel Black Hole

Herdeiro, C. A. R.
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
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By applying a set of Hassan-Sen transformations and string dualities to the Kerr-Godel solution of minimal D=5 supergravity we derive a four parameter family of five dimensional solutions in type II string theory. They describe rotating, charged black holes in a rotating background. For zero background rotation, the solution is D=5 Kerr-Newman; for zero charge it is Kerr-Godel. In a particular extremal limit the solution describes an asymptotically Godel BMPV black hole.; Comment: 12 pages, LaTeX, no figures; v2: one reference added, very minor changes; to appear in CQG

Holographic Protection of Chronology in Universes of the Godel Type

Boyda, Edward; Ganguli, Surya; Horava, Petr; Varadarajan, Uday
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Relevância na Pesquisa
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We analyze the structure of supersymmetric Godel-like cosmological solutions of string theory. Just as the original four-dimensional Godel universe, these solutions represent rotating, topologically trivial cosmologies with a homogeneous metric and closed timelike curves. First we focus on "phenomenological" aspects of holography, and identify the preferred holographic screens associated with inertial comoving observers in Godel universes. We find that holography can serve as a chronology protection agency: The closed timelike curves are either hidden behind the holographic screen, or broken by it into causal pieces. In fact, holography in Godel universes has many features in common with de Sitter space, suggesting that Godel universes could represent a supersymmetric laboratory for addressing the conceptual puzzles of de Sitter holography. Then we initiate the investigation of "microscopic" aspects of holography of Godel universes in string theory. We show that Godel universes are T-dual to pp-waves, and use this fact to generate new Godel-like solutions of string and M-theory by T-dualizing known supersymmetric pp-wave solutions.; Comment: 35 pages, 5 figures. v2: typos corrected, references added

Supersymmetric Godel Universes in String Theory

Harmark, Troels; Takayanagi, Tadashi
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Relevância na Pesquisa
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Supersymmetric backgrounds in string and M-theory of the Godel Universe type are studied. We find several new Godel Universes that preserve up to 20 supersymmetries. In particular, we obtain an interesting Godel Universe in M-theory with 18 supersymmetries which does not seem to be dual to a pp-wave. We show that not only T-duality but also the type-IIA/M-theory S-duality can give supersymmetric Godel Universes from pp-waves. We find solutions that can interpolate between Godel Universes and pp-waves. We also compute the string spectrum on two type IIA Godel Universes. Furthermore, we obtain the spectrum of D-branes on a Godel Universe and find the supergravity solution for a D4-brane on a Godel Universe.; Comment: latex, 36 pages, 1 figure; v2: typos corrected, refs. added, v3: typos corrected

Gödel, percepção racional e compreensão de conceitos

Schultz,Sérgio
Fonte: Revista latinoamericana de filosofía Publicador: Revista latinoamericana de filosofía
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/05/2014 PT
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Nosso objetivo neste artigo é o de lançar luz sobre alguns aspectos das concepções de Gödel acerca da percepção de conceitos. Começamos investigando a natureza e o papel da analogia entre percepção sensível e percepção de conceitos. A seguir, examinamos as conexões entre percepção de conceitos, razão e compreensão, tentando mostrar que a percepção de conceitos é compreensão de conceitos. Por fim, examinamos aqueles aspectos da concepção de Gödel em que a percepção de conceitos de fato se aproxima perigosamente da ideia de um "olho da mente". Contudo, argumentamos que esses aspectos problemáticos não são intrínsecos à noção de percepção de conceitos, mas sim resultam de uma má compreensão da distinção entre conceito e objeto.

CHATEAUBRIAND ON THE NATURE OF LANGUAGE

Sautter, Frank Thomas
Fonte: UNICAMP-CLE-Publicações Publicador: UNICAMP-CLE-Publicações
Tipo: info:eu-repo/semantics/article; info:eu-repo/semantics/publishedVersion; Artigo Avaliado pelos Pares; Formato: application/pdf
Publicado em 11/12/2015 POR
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In the present paper, I raise some questions referring to Chateaubriand’s discussion of the nature of language, its origin, its development and its functions in human live. These questions arise when his view is compared with the partly similar views defended by Gödel and Jørgensen, among others. Resumo: No presente trabalho levanto algumas questões referentes à discussão de Chateaubriand sobre a natureza da linguagem, sua origem, seu desenvolvimento e suas funções na vida humana. Essas questões surgem quando seu ponto de vista é comparado aos pontos de vista parcialmente similares defendidos por Gödel e Jorgensen, entre outros.Palavras chave: Origem da linguagem. Criação. Funções da linguagem. Chateaubriand. Gödel. Jørgensen.