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Sheila Veloso [7]Sheila R. M. Veloso [6]
  1.  17
    On Vague Notions and Modalities: A Modular Approach.Paulo Veloso, Sheila Veloso, Petrúcio Viana, Renata de Freitas & Mario Benevides - 2010 - Logic Journal of the IGPL 18 (3):381-402.
    Vague notions, such as ‘generally’, ‘rarely’, ‘often’, ‘almost always’, ‘a meaningful subset of a whole’, ‘most’, etc., occur often in ordinary language and in some branches of science. We introduce modal logical systems, with generalized operators, for the precise treatment of assertions involving some versions of such vague notions. We examine modal logics, constructed in a modular fashion, with generalized operators corresponding to some versions of ‘generally’ and ‘rarely’.
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  2.  34
    On Ultrafilter Logic and Special Functions.Paulo A. S. Veloso & Sheila R. M. Veloso - 2004 - Studia Logica 78 (3):459-477.
    Logics for generally were introduced for handling assertions with vague notions,such as generally, most, several, etc., by generalized quantifiers, ultrafilter logic being an interesting case. Here, we show that ultrafilter logic can be faithfully embedded into a first-order theory of certain functions, called coherent. We also use generic functions (akin to Skolem functions) to enable elimination of the generalized quantifier. These devices permit using methods for classical first-order logic to reason about consequence in ultrafilter logic.
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  3.  11
    On Modulated Logics for 'Generally' : Some Metamathematical Issues.Sheila R. M. Veloso & Paulo A. S. Veloso - unknown
  4.  4
    Functional Interpretation of Logics for ‘Generally’.Paulo Veloso & Sheila Veloso - 2004 - Logic Journal of the IGPL 12 (6):627-640.
    Logics for ‘generally’ are intended to express some vague notions, such as ‘generally’, ‘several’, ‘many’, ‘most’, etc., by means of the new generalized quantifier ∇ and to reason about assertions with ‘generally’ . We introduce the idea of functional interpretation for ‘generally’ and show that representative functions enable elimination of ∇ and reduce consequence to classical theories. Thus, one can use proof procedures and theorem provers for classical first-order logic to reason about assertions involving ‘generally’.
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  5.  29
    Squares in Fork Arrow Logic.Renata P. de Freitas, Jorge P. Viana, Mario R. F. Benevides, Sheila R. M. Veloso & Paulo A. S. Veloso - 2003 - Journal of Philosophical Logic 32 (4):343-355.
    In this paper we show that the class of fork squares has a complete orthodox axiomatization in fork arrow logic (FAL). This result may be seen as an orthodox counterpart of Venema's non-orthodox axiomatization for the class of squares in arrow logic. FAL is the modal logic of fork algebras (FAs) just as arrow logic is the modal logic of relation algebras (RAs). FAs extend RAs by a binary fork operator and are axiomatized by adding three equations to RAs equational (...)
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  6. On conservative and expansive extensions.Paulo Veloso & Sheila Veloso - 1991 - O Que Nos Faz Pensar:87-106.
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  7.  30
    On ‘Most’ and ‘Representative’: Filter Logic and Special Predicates.Paulo Veloso & Sheila Veloso - 2005 - Logic Journal of the IGPL 13 (6):717-728.
    Logics for ‘generally’ were introduced for handling assertions with vague notions, by non-standard generalized quantifiers, and to reason qualitatively about them . Filter logic is intended to address ‘most’. Here, we show that filter logic can be faithfully embedded into a classical first-order theory of certain predicates, called compatible. We also use representative predicates to enable elimination of the generalized quantifier. These devices permit using classical first-order methods to reason about consequence in filter logic and help clarifying the role of (...)
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  8.  22
    Squares in Fork Arrow Logic.Renata P. De Freitas, Jorge P. Viana, Mario R. F. Benevides, Sheila R. M. Veloso & Paulo A. S. Veloso - 2003 - Journal of Philosophical Logic 32 (4):343 - 355.
    In this paper we show that the class of fork squares has a complete orthodox axiomatization in fork arrow logic (FAL). This result may be seen as an orthodox counterpart of Venema's non-orthodox axiomatization for the class of squares in arrow logic. FAL is the modal logic of fork algebras (FAs) just as arrow logic is the modal logic of relation algebras (RAs). FAs extend RAs by a binary fork operator and are axiomatized by adding three equations to RAs equational (...)
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  9.  26
    On Fork Arrow Logic and its Expressive Power.Paulo A. S. Veloso, Renata P. de Freitas, Petrucio Viana, Mario Benevides & Sheila R. M. Veloso - 2007 - Journal of Philosophical Logic 36 (5):489 - 509.
    We compare fork arrow logic, an extension of arrow logic, and its natural first-order counterpart (the correspondence language) and show that both have the same expressive power. Arrow logic is a modal logic for reasoning about arrow structures, its expressive power is limited to a bounded fragment of first-order logic. Fork arrow logic is obtained by adding to arrow logic the fork modality (related to parallelism and synchronization). As a result, fork arrow logic attains the expressive power of its first-order (...)
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  10.  13
    On Fork Arrow Logic and Its Expressive Power.Paulo A. S. Veloso, Renata P. De Freitas, Petrucio Viana, Mario Benevides & Sheila R. M. Veloso - 2007 - Journal of Philosophical Logic 36 (5):489 - 509.
    We compare fork arrow logic, an extension of arrow logic, and its natural first-order counterpart (the correspondence language) and show that both have the same expressive power. Arrow logic is a modal logic for reasoning about arrow structures, its expressive power is limited to a bounded fragment of first-order logic. Fork arrow logic is obtained by adding to arrow logic the fork modality (related to parallelism and synchronization). As a result, fork arrow logic attains the expressive power of its first-order (...)
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  11.  8
    An Application of Logic Engineering.Sheila Veloso, Paulo Veloso & Renata de Freitas - 2005 - Logic Journal of the IGPL 13 (1):29-46.
    We consider a paradigm of applications of Logic Engineering to illustrate the information interchange among different areas of knowledge, through the formal approach to some aspects of computing. We apply the paradigm to the area of distributed systems, taking the demand for specification formalisms, treated in three areas of knowledge: modal logics, first-order logic and algebra. In doing so, we obtain transfer of intuitions and results, establishing that, as far as input/output representation is concerned, these three formalisms are equivalent.
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  12.  5
    Natural Deduction for ‘Generally’.Leonardo Vana, Paulo Veloso & Sheila Veloso - 2007 - Logic Journal of the IGPL 15 (5-6):775-800.
    Logics for ‘generally’ were introduced for handling assertions with vague notions , which occur often in ordinary language and in science. LG’s provide a framework for distinct notions of ‘generally’: one builds a specific logic for the notion one has in mind. We introduce deductive systems, in natural deduction style, for LG’s and show that these systems are normalizable.
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  13.  5
    On Positive Relational Calculi.Renata de Freitas, Paulo Veloso, Sheila Veloso & Petrucio Viana - 2007 - Logic Journal of the IGPL 15 (5-6):577-601.
    We discuss the question of inclusions between positive relational terms and some of its aspects, using the form of a dialogue. Two possible approaches to the problem are emphasized: natural deduction and graph manipulations. Both provide sound and complete calculi for proving the valid inclusions, supporting nice strategies to obtain proofs in normal form, but the latter appears to present several advantages, which are discussed.
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