7 found
  1.  4
    Agi Kurucz (2009). Weakly Associative Relation Algebras with Projections. Mathematical Logic Quarterly 55 (2):138-153.
    Built on the foundations laid by Peirce, Schröder, and others in the 19th century, the modern development of relation algebras started with the work of Tarski and his colleagues [21, 22]. They showed that relation algebras can capture strong first-order theories like ZFC, and so their equational theory is undecidable. The less expressive class WA of weakly associative relation algebras was introduced by Maddux [7]. Németi [16] showed that WA's have a decidable universal theory. There has been extensive research on (...)
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  2.  1
    David Gabelaia, Agi Kurucz, Frank Wolter & Michael Zakharyaschev (2006). Non-Primitive Recursive Decidability of Products of Modal Logics with Expanding Domains. Annals of Pure and Applied Logic 142 (1):245-268.
    We show that—unlike products of ‘transitive’ modal logics which are usually undecidable—their ‘expanding domain’ relativisations can be decidable, though not in primitive recursive time. In particular, we prove the decidability and the finite expanding product model property of bimodal logics interpreted in two-dimensional structures where one component—call it the ‘flow of time’—is • a finite linear order or a finite transitive tree and the other is composed of structures like • transitive trees/partial orders/quasi-orders/linear orders or only finite such structures expanding (...)
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  3.  12
    David Gabelaia, Agi Kurucz, Frank Wolter & Michael Zakharyaschev (2005). Products of 'Transitive' Modal Logics. Journal of Symbolic Logic 70 (3):993-1021.
    We solve a major open problem concerning algorithmic properties of products of ‘transitive’ modal logics by showing that products and commutators of such standard logics as K4, S4, S4.1, K4.3, GL, or Grz are undecidable and do not have the finite model property. More generally, we prove that no Kripke complete extension of the commutator [K4,K4] with product frames of arbitrary finite or infinite depth (with respect to both accessibility relations) can be decidable. In particular, if.
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  4.  21
    Roman Kontchakov, Agi Kurucz & Michael Zakharyaschev (2005). Undecidability of First-Order Intuitionistic and Modal Logics with Two Variables. Bulletin of Symbolic Logic 11 (3):428-438.
    We prove that the two-variable fragment of first-order intuitionistic logic is undecidable, even without constants and equality. We also show that the two-variable fragment of a quantified modal logic L with expanding first-order domains is undecidable whenever there is a Kripke frame for L with a point having infinitely many successors (such are, in particular, the first-order extensions of practically all standard modal logics like K, K4, GL, S4, S5, K4.1, S4.2, GL.3, etc.). For many quantified modal logics, including those (...)
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  5.  19
    Agi Kurucz & Sérgio Marcelino (2012). Non-Finitely Axiomatisable Two-Dimensional Modal Logics. Journal of Symbolic Logic 77 (3):970-986.
    We show the first examples of recursively enumerable (even decidable) two-dimensional products of finitely axiomatisable modal logics that are not finitely axiomatisable. In particular, we show that any axiomatisation of some bimodal logics that are determined by classes of product frames with linearly ordered first components must be infinite in two senses: It should contain infinitely many propositional variables, and formulas of arbitrarily large modal nesting-depth.
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    Agi Kurucz (2013). A Note on Axiomatisations of Two-Dimensional Modal Logics. In Kamal Lodaya (ed.), Logic and its Applications. Springer. pp. 27--33.
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  7.  19
    Miklós Erdélyi-Szabó, László Kálmán & Agi Kurucz (2008). Towards a Natural Language Semantics Without Functors and Operands. Journal of Logic, Language and Information 17 (1):1-17.
    The paper sets out to offer an alternative to the function/argument approach to the most essential aspects of natural language meanings. That is, we question the assumption that semantic completeness (of, e.g., propositions) or incompleteness (of, e.g., predicates) exactly replicate the corresponding grammatical concepts (of, e.g., sentences and verbs, respectively). We argue that even if one gives up this assumption, it is still possible to keep the compositionality of the semantic interpretation of simple predicate/argument structures. In our opinion, compositionality presupposes (...)
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