960 research outputs found

    Nominal Unification from a Higher-Order Perspective

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    Nominal Logic is a version of first-order logic with equality, name-binding, renaming via name-swapping and freshness of names. Contrarily to higher-order logic, bindable names, called atoms, and instantiable variables are considered as distinct entities. Moreover, atoms are capturable by instantiations, breaking a fundamental principle of lambda-calculus. Despite these differences, nominal unification can be seen from a higher-order perspective. From this view, we show that nominal unification can be reduced to a particular fragment of higher-order unification problems: Higher-Order Pattern Unification. This reduction proves that nominal unification can be decided in quadratic deterministic time, using the linear algorithm for Higher-Order Pattern Unification. We also prove that the translation preserves most generality of unifiers

    Control of a converter for photovoltaic plants

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    This project presents a model of the process involved in obtaining electrical energy from sunlight. The solar energy is a growing resource of energy, so it has been analyzed its process of conversion for a better understanding. It is intended to expose in the clearest way a photovoltaic system with its most essential elements. With the software package Matlab/Simulink, a photovoltaic array and a VSC power converter connected to the grid will be modeled. They will be studied separately and together, exposing its model blocks and equations, implementing different control variables in order to examine the variations in the system conduct, obtaining finally a way to maximize the power generated by the system

    On the complexity of bounded second-order unification and stratified context unification

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    Bounded Second-Order Unification is a decidable variant of undecidable Second-Order Unification. Stratified Context Unification is a decidable restriction of Context Unification, whose decidability is a long-standing open problem. This paper is a join of two separate previous, preliminary papers on NP-completeness of Bounded Second-Order Unification and Stratified Context Unification. It clarifies some omissions in these papers, joins the algorithmic parts that construct a minimal solution, and gives a clear account of a method of using singleton tree grammars for compression that may have potential usage for other algorithmic questions in related areas. © The Author 2010. Published by Oxford University Press. All rights reserved.This research has been partially supported by the research projects Mulog-2 (TIN2007-68005-C04-01) and SuRoS TIN2008-04547) funded by the CICyTPeer Reviewe

    Comparison between 2D and 3D modelling of sediment transport: application to the dune evolution

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    River morphodynamics and sediment transportMechanics of sediment transpor

    The Complexity of 3-Valued Lukasiewicz Rules

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    It is known that determining the satisfiability of n-valued Łukasiewicz rules is NP-complete for n ≥ 4, as well as that it can be solved in time linear in the length of the formula in the Boolean case (when n = 2). However, the complexity for n = 3 is an open problem. In this paper we formally prove that the satisfiability problem for 3-valued Łukasiewicz rules is NP-complete. Moreover, we also prove that when the consequent of the rule has at most one element, the problem is polynomially solvable. © Springer International Publishing Switzerland 2015.Research partially supported by the Generalitat de Catalunya grant AGAUR 2014-SGR-118, and the Ministerio de Economía y Competividad projects AT CONSOLIDER CSD2007-0022, INGENIO 2010, CO-PRIVACY TIN2011-27076-C03-03, EDETRI TIN2012-39348-C02-01 and HeLo TIN2012-33042. The second author was supported by Mobility Grant PRX14/00195 of the Ministerio de Educación, Cultura y DeportePeer reviewe
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