Results for 'Istvan Hajnal'

565 found
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  1.  94
    Omitting types for finite variable fragments and complete representations of algebras.Hajnal Andréka, István Németi & Tarek Sayed Ahmed - 2008 - Journal of Symbolic Logic 73 (1):65-89.
    We give a novel application of algebraic logic to first order logic. A new, flexible construction is presented for representable but not completely representable atomic relation and cylindric algebras of dimension n (for finite n > 2) with the additional property that they are one-generated and the set of all n by n atomic matrices forms a cylindric basis. We use this construction to show that the classical Henkin-Orey omitting types theorem fails for the finite variable fragments of first order (...)
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  2.  32
    Testing Definitional Equivalence of Theories Via Automorphism Groups.Hajnal Andréka, Judit Madarász, István Németi & Gergely Székely - 2024 - Review of Symbolic Logic 17 (4):1097-1118.
    Two first-order logic theories are definitionally equivalent if and only if there is a bijection between their model classes that preserves isomorphisms and ultraproducts (Theorem 2). This is a variant of a prior theorem of van Benthem and Pearce. In Example 2, uncountably many pairs of definitionally inequivalent theories are given such that their model categories are concretely isomorphic via bijections that preserve ultraproducts in the model categories up to isomorphism. Based on these results, we settle several conjectures of Barrett, (...)
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  3. Modal Languages and Bounded Fragments of Predicate Logic.Hajnal Andréka, István Németi & Johan van Benthem - 1998 - Journal of Philosophical Logic 27 (3):217 - 274.
    What precisely are fragments of classical first-order logic showing “modal” behaviour? Perhaps the most influential answer is that of Gabbay 1981, which identifies them with so-called “finite-variable fragments”, using only some fixed finite number of variables (free or bound). This view-point has been endorsed by many authors (cf. van Benthem 1991). We will investigate these fragments, and find that, illuminating and interesting though they are, they lack the required nice behaviour in our sense. (Several new negative results support this claim.) (...)
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  4. Quasi Equational Logic Of Partial Algebras.Hajnal Andreka, Peter Burmeister & Istvan Nemeti - 1980 - Bulletin of the Section of Logic 9 (4):193-197.
     
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  5. A logic road from special relativity to general relativity.Hajnal Andréka, Judit X. Madarász, István Németi & Gergely Székely - 2012 - Synthese 186 (3):633 - 649.
    We present a streamlined axiom system of special relativity in first-order logic. From this axiom system we "derive" an axiom system of general relativity in two natural steps. We will also see how the axioms of special relativity transform into those of general relativity. This way we hope to make general relativity more accessible for the non-specialist.
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  6. Completeness of Floyd logic.Hajnal Andreka & Istvan Nemeti - 1978 - Bulletin of the Section of Logic 7 (3):115-119.
    This is an abstract of our paper \A characterisation of Floyd-provable programs" submitted to Theoretical Computer Science. ! denotes the set of natural numbers. Y =d fyi : i 2 !g is the set of variable symbols. L denotes the set of classical rst order formulas of type t possibly with free variables , where t is the similarity type of arithmetic, i.e. it consists of \+; ; 0; 1" with arities \2; 2; 0; 0".
     
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  7.  53
    On universal algebraic logic and cylindric algebras.Hajnal Andréka & István Németi - 1978 - Bulletin of the Section of Logic 7 (4):152-158.
  8.  69
    Relativised quantification: Some canonical varieties of sequence-set algebras.Hajnal Andreka, Robert Goldblatt & Istvan Nemeti - 1998 - Journal of Symbolic Logic 63 (1):163-184.
  9.  33
    On A New Semantics for First-Order Predicate Logic.István Németi, Johan Benthem & Hajnal Andréka - 2017 - Journal of Philosophical Logic 46 (3):259-267.
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  10. Program verification within and without logic.Hajnal Andreka, Istvan Nemeti & Ildiko Sain - 1979 - Bulletin of the Section of Logic 8 (3):124-128.
    Theorem 1 states a negative result about the classical semantics j= ! of program schemes. Theorem 2 investigates the reason for this. We conclude that Theorem 2 justies the Henkin-type semantics j= for which the opposite of the present Theorem 1 was proved in [1]{[3] and also in a dierent form in part III of [5]. The strongest positive result on j= is Corollary 6 in [3].
     
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  11.  36
    Two-variable logic has weak, but not strong, Beth definability.Hajnal Andréka & István Németi - 2021 - Journal of Symbolic Logic 86 (2):785-800.
    We prove that the two-variable fragment of first-order logic has the weak Beth definability property. This makes the two-variable fragment a natural logic separating the weak and the strong Beth properties since it does not have the strong Beth definability property.
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  12.  66
    Mutual definability does not imply definitional equivalence, a simple example.Hajnal Andréka, Judit X. Madarász & István Németi - 2005 - Mathematical Logic Quarterly 51 (6):591-597.
    We give two theories, Th1 and Th2, which are explicitly definable over each other , but are not definitionally equivalent. The languages of the two theories are disjoint.
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  13.  44
    Notions of density that imply representability in algebraic logic.Hajnal Andréka, Steven Givant, Szabolcs Mikulás, István Németi & András Simon - 1998 - Annals of Pure and Applied Logic 91 (2-3):93-190.
    Henkin and Tarski proved that an atomic cylindric algebra in which every atom is a rectangle must be representable . This theorem and its analogues for quasi-polyadic algebras with and without equality are formulated in Henkin, Monk and Tarski [13]. We introduce a natural and more general notion of rectangular density that can be applied to arbitrary cylindric and quasi-polyadic algebras, not just atomic ones. We then show that every rectangularly dense cylindric algebra is representable, and we extend this result (...)
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  14.  99
    Axiomatizing relativistic dynamics without conservation postulates.Hajnal Andréka, Judit Madarász X., István Németi & Gergely Székely - 2008 - Studia Logica 89 (2):163 - 186.
    A part of relativistic dynamics is axiomatized by simple and purely geometrical axioms formulated within first-order logic. A geometrical proof of the formula connecting relativistic and rest masses of bodies is presented, leading up to a geometric explanation of Einstein’s famous E = mc 2. The connection of our geometrical axioms and the usual axioms on the conservation of mass, momentum and four-momentum is also investigated.
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  15.  60
    General algebraic logic: A perspective on “what is logic”.Istvan Nemeti & Hajnal Andreka - 1994 - In Dov M. Gabbay (ed.), What is a logical system? New York: Oxford University Press.
  16.  46
    Back and Forth Between Modal Logic and Classical Logic.Hajnal Andreka, Johan van Benthem & Istvan Nemeti - 1995 - Logic Journal of the IGPL 3 (5):685-720.
  17.  30
    On tarski’s axiomatic foundations of the calculus of relations.Hajnal Andréka, Steven Givant, Peter Jipsen & István Németi - 2017 - Journal of Symbolic Logic 82 (3):966-994.
    It is shown that Tarski’s set of ten axioms for the calculus of relations is independent in the sense that no axiom can be derived from the remaining axioms. It is also shown that by modifying one of Tarski’s axioms slightly, and in fact by replacing the right-hand distributive law for relative multiplication with its left-hand version, we arrive at an equivalent set of axioms which is redundant in the sense that one of the axioms, namely the second involution law, (...)
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  18.  44
    Nonrepresentable relation algebras from groups.Hajnal Andréka, István Németi & Steven Givant - 2020 - Review of Symbolic Logic 13 (4):861-881.
    A series of nonrepresentable relation algebras is constructed from groups. We use them to prove that there are continuum many subvarieties between the variety of representable relation algebras and the variety of coset relation algebras. We present our main construction in terms of polygroupoids.
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  19.  58
    The lattice of varieties of representable relation algebras.Hajnal Andréka, Steven Givant & István Németi - 1994 - Journal of Symbolic Logic 59 (2):631-661.
    We shall show that certain natural and interesting intervals in the lattice of varieties of representable relation algebras embed the lattice of all subsets of the natural numbers, and therefore must have a very complicated lattice-theoretic structure.
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  20.  66
    On A New Semantics for First-Order Predicate Logic.István Németi, Johan van Benthem & Hajnal Andréka - 2017 - Journal of Philosophical Logic 46 (3):259-267.
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  21.  18
    Het analyseren van partij-rangschikkingen via het 'exploded logit'-model.Istvan Hajnal & Bart Maddens - 1997 - Res Publica 39 (3):423-438.
    Rankings of politicalparties are often used to map the multiple party preference of the electorate. This article shows how the obtained rankings may be analysed by means of the exploded logit-technique, which allows for testing both the difference between the rankings and the effect of either categorical or quantitative independent variables on the rankings. An analysis of the effect of age on the party preference rankings of the christian democratie electorate in the 1991 Belgian parliamentary election shows that the older (...)
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  22. Expressibility of properties of relations.Hajnal Andréka, Ivo Düntsch & István Németi - 1995 - Journal of Symbolic Logic 60 (3):970-991.
    We investigate in an algebraic setting the question of which logical languages can express the properties integral, permutational, and rigid for algebras of relations.
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  23.  23
    Nonrepresentable relation algebras from groups - addendum.Hajnal Andréka, István Németi & Steven Givant - 2019 - Review of Symbolic Logic 12 (4):892-892.
  24.  14
    Logic Families.Hajnal Andréka, Zalán Gyenis, István Németi & Ildikó Sain - forthcoming - Studia Logica:1-47.
    A logic family is a bunch of logics that belong together in some way. First-order logic is one of the examples. Logics organized into a structure occur in abstract model theory, institution theory and in algebraic logic. Logic families play a role in adopting methods for investigating sentential logics to first-order like logics. We thoroughly discuss the notion of logic families as defined in the recent Universal Algebraic Logic book.
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  25.  62
    Not all representable cylindric algebras are neat reducts.Hajnal Andréka & István Németi - 1979 - Bulletin of the Section of Logic 8 (3):145-147.
  26.  28
    Complexity in the interdefinability of timelike, lightlike and spacelike relatedness of Minkowski spacetime.Hajnal Andréka, Judit X. Madarász, István Németi & Gergely Székely - 2022 - Annals of Pure and Applied Logic 173 (5):103100.
  27.  58
    Perfect extensions and derived algebras.Hajnal Andréka, Steven Givant & István Németi - 1995 - Journal of Symbolic Logic 60 (3):775-796.
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  28. A twist in the geometry of rotating Black holes: Seeking the cause of acausality.Christian Wüthrich, Hajnal Andréka & István Németi - manuscript
    We investigate Kerr–Newman black holes in which a rotating charged ring-shaped singularity induces a region which contains closed timelike curves (CTCs). Contrary to popular belief, it turns out that the time orientation of the CTC is oppo- site to the direction in which the singularity or the ergosphere rotates. In this sense, CTCs “counter-rotate” against the rotating black hole. We have similar results for all spacetimes sufficiently familiar to us in which rotation induces CTCs. This motivates our conjecture that perhaps (...)
     
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  29.  49
    Socialising technology: the archives of István Hajnal.Péter Szirák - 2008 - Studies in East European Thought 60 (1-2):135-147.
    István Hajnal is one of the most remarkable historians and a forerunner of research on the history of communication. He developed his radical theories on the connections between writing as a technique and social structure mainly in the first half of the twentieth century. He emphasized, in a unique way, the importance of technology for social development arguing that the transformation of social structures and the individual within stand in a mutual and interdependent relation with various technological systems. While (...)
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  30.  46
    Hajnal Andréka and István Németi on Unity of Science: From Computing to Relativity Theory Through Algebraic Logic.Judit Madarász & Gergely Székely (eds.) - 2021 - Springer.
    This book features more than 20 papers that celebrate the work of Hajnal Andréka and István Németi. It illustrates an interaction between developing and applying mathematical logic. The papers offer new results as well as surveys in areas influenced by these two outstanding researchers. They also provide details on the after-life of some of their initiatives. Computer science connects the papers in the first part of the book. The second part concentrates on algebraic logic. It features a range of (...)
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  31.  85
    Using Mathematics to Explain a Scientific Theory.Michèle Friend & Daniele Molinini - 2016 - Philosophia Mathematica 24 (2):185-213.
    We answer three questions: 1. Can we give a wholly mathematical explanation of a physical phenomenon? 2. Can we give a wholly mathematical explanation for a whole physical theory? 3. What is gained or lost in giving a wholly, or partially, mathematical explanation of a phenomenon or a scientific theory? To answer these questions we look at a project developed by Hajnal Andréka, Judit Madarász, István Németi and Gergely Székely. They, together with collaborators, present special relativity theory in a (...)
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  32. Relativistic Computers and the Turing Barrier.István Németi & Gyula Dávid - 2006 - Journal of Applied Mathematics and Computation 178:118--42.
  33.  37
    Marxism, the Capital System, and Social Revolution: An Interview with István Mészáros.István Mészáros - 1999 - Science and Society 63 (3):338 - 361.
  34. Marx's Theory of Alienation.István Mészáros - 1970 - Studies in Soviet Thought 13 (1):137-137.
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  35.  34
    Representations for Small Relation Algebras.Hajnal Andréka & Roger D. Maddux - 1994 - Notre Dame Journal of Formal Logic 35 (4):550-562.
    There are eighteen isomorphism types of finite relation algebras with eight or fewer elements, and all of them are representable. We determine all the cardinalities of sets on which these algebras have representations.
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  36.  40
    Complexity of equations valid in algebras of relations part I: Strong non-finitizability.Hajnal Andréka - 1997 - Annals of Pure and Applied Logic 89 (2):149-209.
    We study algebras whose elements are relations, and the operations are natural “manipulations” of relations. This area goes back to 140 years ago to works of De Morgan, Peirce, Schröder . Well known examples of algebras of relations are the varieties RCAn of cylindric algebras of n-ary relations, RPEAn of polyadic equality algebras of n-ary relations, and RRA of binary relations with composition. We prove that any axiomatization, say E, of RCAn has to be very complex in the following sense: (...)
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  37.  27
    Meaningfulness Beats Frequency in Multiword Chunk Processing.Hajnal Jolsvai, Stewart M. McCauley & Morten H. Christiansen - 2020 - Cognitive Science 44 (10):e12885.
    Whereas a growing bulk of work has demonstrated that both adults and children are sensitive to frequently occurring word sequences, little is known about the potential role of meaning in the processing of such multiword chunks. Here, we take a first step toward assessing the contribution of meaningfulness in the processing of multiword sequences, using items that varied in chunk meaningfulness. In a phrasal-decision study, we compared reaction times for triads of three-word sequences, corresponding to idiomatic expressions, compositional phrases, and (...)
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  38.  5
    It's war, let's marry.István Zárdai - 2024 - Philosophy and Photography Lab.
    A short discussion on how photography can capture the sturdiness lent to our personality by our long-term policies structuring our reasoning, even during times of war and other cataclysms.
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  39.  21
    L’aspect pneumatologique de la vie morale du chrétien selon Jean Chrysostome.István Baán - 1997 - Augustinianum 37 (2):327-331.
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  40.  12
    Inhalt.István Czakó - 2014 - In Geist Und Unsterblichkeit: Grundprobleme der Religionsphilosophie Und Eschatologie Im Denken Søren Kierkegaards. De Gruyter.
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  41.  19
    Unsterblichkeitsfurcht.István Czakó - 2007 - Kierkegaard Studies Yearbook 2007 (1):227-254.
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  42. Análisis nominalista de una entidad que está siendo caracterizada / “Nominalist Analyses of an Entity Being Charactered.Michael Anthony Istvan - 2013 - Discusiones Filosóficas 13 (21):87-93.
    This paper is intended primarily as a reference tool for participants in the debate between realism and nominalism concerning universals. It provides an exhaustive catalogue of the basic analyses of an entity being charactered that nominalists can employ in both a constituent and nonconstituent ontology.
     
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  43. Király V. István - Death and History.István Király V. - 2016 - Budapesti Konyv Szemle (2):79-83.
    Recenzio Kiraly V. Istvan Death and History c. konyverol.
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  44.  17
    Intercultural Pragmatics.Istvan Kecskes - 2013 - Oxford University Press USA.
    Intercultural Pragmatics studies how language systems are used in social encounters between speakers who have different first languages and cultures, yet communicate in a common language. The field first emerged in the early 21st century, joining two seemingly antagonistic approaches to pragmatics research: the cognitive-philosophical approach, which considers intention as an a priori mental state of the speaker, and the sociocultural-interactional approach, which considers it as a post factum construct created by both speaker and hearer though conversation. Istvan Kecskes, (...)
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  45.  87
    Logical Pantheism.István Aranyosi - 2022 - Philosophy Compass 17 (7):e12857.
    Philosophy Compass, Volume 17, Issue 7, July 2022.
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  46.  15
    Giving thickness to the minimal self: coenesthetic depth and the materiality of consciousness.István Fazakas, Mathilde Bois & Tudi Gozé - forthcoming - Phenomenology and the Cognitive Sciences:1-21.
    Contemporary phenomenological psychopathology has raised questions concerning selfhood and its possible alterations in schizophrenia spectrum disorders. Although the notion of the self is central to several accounts of anomalies, it remains a question how exactly the radically minimal experiential features of selfhood can be altered. Indeed, the risk is to reduce the notion of selfhood so drastically, that it can no longer account for alterations of experience. Here we propose to give thickness to the minimal self. To do this we (...)
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  47.  32
    The class of neat-reducts of cylindric algebras is not a variety but is closed w.r.t. HP.István Németi - 1983 - Notre Dame Journal of Formal Logic 24:399-409.
  48. Interview: István Mészéros: Marxism Today.Chris Arthur, Joseph Mccarney & István Mészaros - 1992 - Radical Philosophy 62.
     
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  49. The Problemata physica : an introduction 1.Istvan Bodnar - 2015 - In Robert Mayhew (ed.), The Aristotelian Problemata Physica : Philosophical and Scientific Investigations. Boston: Brill.
     
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  50.  13
    1 Die Aufhebung der klassischen theologia naturalis in der negativen Theologie des Johannes Climacus.István Czakó - 2014 - In Geist Und Unsterblichkeit: Grundprobleme der Religionsphilosophie Und Eschatologie Im Denken Søren Kierkegaards. De Gruyter. pp. 17-55.
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