22,529 research outputs found

    A Note on Parameterised Knowledge Operations in Temporal Logic

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    We consider modeling the conception of knowledge in terms of temporal logic. The study of knowledge logical operations is originated around 1962 by representation of knowledge and belief using modalities. Nowadays, it is very good established area. However, we would like to look to it from a bit another point of view, our paper models knowledge in terms of linear temporal logic with {\em past}. We consider various versions of logical knowledge operations which may be defined in this framework. Technically, semantics, language and temporal knowledge logics based on our approach are constructed. Deciding algorithms are suggested, unification in terms of this approach is commented. This paper does not offer strong new technical outputs, instead we suggest new approach to conception of knowledge (in terms of time).Comment: 10 page

    The Logic behind Feynman's Paths

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    The classical notions of continuity and mechanical causality are left in order to refor- mulate the Quantum Theory starting from two principles: I) the intrinsic randomness of quantum process at microphysical level, II) the projective representations of sym- metries of the system. The second principle determines the geometry and then a new logic for describing the history of events (Feynman's paths) that modifies the rules of classical probabilistic calculus. The notion of classical trajectory is replaced by a history of spontaneous, random an discontinuous events. So the theory is reduced to determin- ing the probability distribution for such histories according with the symmetries of the system. The representation of the logic in terms of amplitudes leads to Feynman rules and, alternatively, its representation in terms of projectors results in the Schwinger trace formula.Comment: 15 pages, contribution to Mario Castagnino Festschrif

    Non-uniformizable sets with countable cross-sections on a given level of the projective hierarchy

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    We present a model of set theory, in which, for a given n≄2n\ge2, there exists a non-ROD-uniformizable planar lightface Πn1\varPi^1_n set in R×R\mathbb R\times\mathbb R, whose all vertical cross-sections are countable sets (and in fact Vitali classes), while all planar boldface ÎŁn1\bf\Sigma^1_n sets with countable cross-sections are Δn+11\bf\Delta^1_{n+1}-uniformizable. Thus it is true in this model, that the ROD-uniformization principle for sets with countable cross-sections first fails precisely at a given projective level.Comment: A revised version of the originally submitted preprin
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