45,898 research outputs found

    The Topology-Free Construction of the Universal Type Structure for Conditional Probability Systems

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    We construct the universal type structure for conditional probability systems without any topological assumption, namely a type structure that is terminal, belief-complete, and non-redundant. In particular, in order to obtain the belief-completeness in a constructive way, we extend the work of Meier [An Infinitary Probability Logic for Type Spaces. Israel Journal of Mathematics, 192, 1-58] by proving strong soundness and strong completeness of an infinitary conditional probability logic with truthful and non-epistemic conditioning events.Comment: In Proceedings TARK 2017, arXiv:1707.0825

    Logic + control: An example

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    We present a Prolog program - the SAT solver of Howe and King - as a (pure) logic program with added control. The control consists of a selection rule (delays of Prolog) and pruning the search space. We construct the logic program together with proofs of its correctness and completeness, with respect to a formal specification. Correctness and termination of the logic program are inherited by the Prolog program; the change of selection rule preserves completeness. We prove that completeness is also preserved by one case of pruning; for the other an informal justification is presented. For proving correctness we use a method, which should be well known but is often neglected. For proving program completeness we employ a new, simpler variant of a method published previously. We point out usefulness of approximate specifications. We argue that the proof methods correspond to natural declarative thinking about programs, and that they can be used, formally or informally, in every-day programming

    Algorithmic correspondence and completeness in modal logic. I. The core algorithm SQEMA

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    Modal formulae express monadic second-order properties on Kripke frames, but in many important cases these have first-order equivalents. Computing such equivalents is important for both logical and computational reasons. On the other hand, canonicity of modal formulae is important, too, because it implies frame-completeness of logics axiomatized with canonical formulae. Computing a first-order equivalent of a modal formula amounts to elimination of second-order quantifiers. Two algorithms have been developed for second-order quantifier elimination: SCAN, based on constraint resolution, and DLS, based on a logical equivalence established by Ackermann. In this paper we introduce a new algorithm, SQEMA, for computing first-order equivalents (using a modal version of Ackermann's lemma) and, moreover, for proving canonicity of modal formulae. Unlike SCAN and DLS, it works directly on modal formulae, thus avoiding Skolemization and the subsequent problem of unskolemization. We present the core algorithm and illustrate it with some examples. We then prove its correctness and the canonicity of all formulae on which the algorithm succeeds. We show that it succeeds not only on all Sahlqvist formulae, but also on the larger class of inductive formulae, introduced in our earlier papers. Thus, we develop a purely algorithmic approach to proving canonical completeness in modal logic and, in particular, establish one of the most general completeness results in modal logic so far.Comment: 26 pages, no figures, to appear in the Logical Methods in Computer Scienc

    Phase semantics and decidability of elementary affine logic

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    AbstractLight, elementary and soft linear logics are formal systems derived from Linear Logic, enjoying remarkable normalization properties. In this paper, we prove decidability of Elementary Affine Logic, EAL. The result is obtained by semantical means, first defining a class of phase models for EAL and then proving soundness and (strong) completeness, following Okada's technique. Phase models for Light Affine Logic and Soft Linear Logic are also defined and shown complete

    A simple proof that super consistency implies cut elimination

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    International audienceWe give a simple and direct proof that super-consistency implies the cut elimination property in deduction modulo. This proof can be seen as a simpli cation of the proof that super-consistency implies proof normalization. It also takes ideas from the semantic proofs of cut elimination that proceed by proving the completeness of the cut-free calculus. As an application, we compare our work with the cut elimination theorems in higher-order logic that involve V-complexes
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