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João Rasga [11]J. Rasga [7]
  1.  8
    A Graph-Theoretic Account of Logics.A. Sernadas, C. Sernadas, J. Rasga & Marcelo E. Coniglio - 2009 - Journal of Logic and Computation 19 (6):1281-1320.
    A graph-theoretic account of logics is explored based on the general notion of m-graph (that is, a graph where each edge can have a finite sequence of nodes as source). Signatures, interpretation structures and deduction systems are seen as m-graphs. After defining a category freely generated by a m-graph, formulas and expressions in general can be seen as morphisms. Moreover, derivations involving rule instantiation are also morphisms. Soundness and completeness theorems are proved. As a consequence of the generality of the (...)
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  2.  7
    Importing Logics.João Rasga, Amílcar Sernadas & Cristina Sernadas - 2012 - Studia Logica 100 (3):545-581.
    The novel notion of importing logics is introduced, subsuming as special cases several kinds of asymmetric combination mechanisms, like temporalization [8, 9], modalization [7] and exogenous enrichment [13, 5, 12, 4, 1]. The graph-theoretic approach proposed in [15] is used, but formulas are identified with irreducible paths in the signature multi-graph instead of equivalence classes of such paths, facilitating proofs involving inductions on formulas. Importing is proved to be strongly conservative. Conservative results follow as corollaries for temporalization, modalization and exogenous (...)
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  3.  30
    Modulated Fibring and the Collapsing Problem.Cristina Sernadas, João Rasga & Walter A. Carnielli - 2002 - Journal of Symbolic Logic 67 (4):1541-1569.
    Fibring is recognized as one of the main mechanisms in combining logics, with great signicance in the theory and applications of mathematical logic. However, an open challenge to bring is posed by the collapsing problem: even when no symbols are shared, certain combinations of logics simply collapse to one of them, indicating that bring imposes unwanted interconnections between the given logics. Modulated bring allows a ner control of the combination, solving the collapsing problem both at the semantic and deductive levels. (...)
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  4.  12
    Craig Interpolation in the Presence of Unreliable Connectives.João Rasga, Cristina Sernadas & Amlcar Sernadas - 2014 - Logica Universalis 8 (3-4):423-446.
    Arrow and turnstile interpolations are investigated in UCL [introduced by Sernadas et al. ], a logic that is a complete extension of classical propositional logic for reasoning about connectives that only behave as expected with a given probability. Arrow interpolation is shown to hold in general and turnstile interpolation is established under some provisos.
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  5.  12
    Importing Logics: Soundness and Completeness Preservation. [REVIEW]J. Rasga, A. Sernadas & C. Sernadas - 2013 - Studia Logica 101 (1):117-155.
    Importing subsumes several asymmetric ways of combining logics, including modalization and temporalization. A calculus is provided for importing, inheriting the axioms and rules from the given logics and including additional rules for lifting derivations from the imported logic. The calculus is shown to be sound and concretely complete with respect to the semantics of importing as proposed in J. Rasga et al. (100(3):541–581, 2012) Studia Logica.
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  6.  7
    Sufficient Conditions for Cut Elimination with Complexity Analysis.João Rasga - 2007 - Annals of Pure and Applied Logic 149 (1):81-99.
    Sufficient conditions for first-order-based sequent calculi to admit cut elimination by a Schütte–Tait style cut elimination proof are established. The worst case complexity of the cut elimination is analysed. The obtained upper bound is parameterized by a quantity related to the calculus. The conditions are general enough to be satisfied by a wide class of sequent calculi encompassing, among others, some sequent calculi presentations for the first order and the propositional versions of classical and intuitionistic logic, classical and intuitionistic modal (...)
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  7.  5
    Decision and Optimization Problems in the Unreliable-Circuit Logic.J. Rasga, C. Sernadas, P. Mateus & A. Sernadas - 2017 - Logic Journal of the IGPL 25 (3):283-308.
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  8.  20
    On Graph-Theoretic Fibring of Logics.A. Sernadas, C. Sernadas, J. Rasga & M. Coniglio - 2009 - Journal of Logic and Computation 19 (6):1321-1357.
    A graph-theoretic account of fibring of logics is developed, capitalizing on the interleaving characteristics of fibring at the linguistic, semantic and proof levels. Fibring of two signatures is seen as a multi-graph (m-graph) where the nodes and the m-edges include the sorts and the constructors of the signatures at hand. Fibring of two models is a multi-graph (m-graph) where the nodes and the m-edges are the values and the operations in the models, respectively. Fibring of two deductive systems is an (...)
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  9.  16
    Interpolation Via Translations.João Rasga, Walter Carnielli & Cristina Sernadas - 2009 - Mathematical Logic Quarterly 55 (5):515-534.
    A new technique is presented for proving that a consequence system enjoys Craig interpolation or Maehara interpolation based on the fact that these properties hold in another consequence system. This technique is based on the existence of a back and forth translation satisfying some properties between the consequence systems. Some examples of translations satisfying those properties are described. Namely a translation between the global/local consequence systems induced by fragments of linear logic, a Kolmogorov-Gentzen-Gödel style translation, and a new translation between (...)
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  10.  9
    Completeness and Interpolation of Almost‐Everywhere Quantification Over Finitely Additive Measures.João Rasga, Wafik Boulos Lotfallah & Cristina Sernadas - 2013 - Mathematical Logic Quarterly 59 (4-5):286-302.
  11.  9
    On Combined Connectives.A. Sernadas, C. Sernadas & J. Rasga - 2011 - Logica Universalis 5 (2):205-224.
    Combined connectives arise in combined logics. In fibrings, such combined connectives are known as shared connectives and inherit the logical properties of each component. A new way of combining connectives (and other language constructors of propositional nature) is proposed by inheriting only the common logical properties of the components. A sound and complete calculus is provided for reasoning about the latter. The calculus is shown to be a conservative extension of the original calculus. Examples are provided contributing to a better (...)
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  12.  6
    Fibring as Biporting Subsumes Asymmetric Combinations.J. Rasga, A. Sernadas & C. Sernadas - 2014 - Studia Logica 102 (5):1041-1074.
    The transference of preservation results between importing and unconstrained fibring is investigated. For that purpose, a new formulation of fibring, called biporting, is introduced, and importing is shown to be subsumed by biporting. In consequence, particular cases of importing, like temporalization, modalization and globalization are subsumed by fibring. Capitalizing on these results, the preservation of the finite model property by fibring is transferred to importing and then carried over to globalization.
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  13.  5
    Truth-Values as Labels: A General Recipe for Labelled Deduction.Cristina Sernadas, Luca Viganò, João Rasga & Amílcar Sernadas - 2003 - Journal of Applied Non-Classical Logics 13 (3-4):277-315.
  14.  1
    Preservation of Craig Interpolation by the Product of Matrix Logics.C. Sernadas, J. Rasga & A. Sernadas - 2013 - Journal of Applied Logic 11 (3):328-349.