519 research outputs found

    A map on the space of rational functions

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    We describe dynamical properties of a map F\mathfrak{F} defined on the space of rational functions. The fixed points of F\mathfrak{F} are classified and the long time behavior of a subclass is described in terms of Eulerian polynomials

    Upper and Lower Bounds for Weak Backdoor Set Detection

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    We obtain upper and lower bounds for running times of exponential time algorithms for the detection of weak backdoor sets of 3CNF formulas, considering various base classes. These results include (omitting polynomial factors), (i) a 4.54^k algorithm to detect whether there is a weak backdoor set of at most k variables into the class of Horn formulas; (ii) a 2.27^k algorithm to detect whether there is a weak backdoor set of at most k variables into the class of Krom formulas. These bounds improve an earlier known bound of 6^k. We also prove a 2^k lower bound for these problems, subject to the Strong Exponential Time Hypothesis.Comment: A short version will appear in the proceedings of the 16th International Conference on Theory and Applications of Satisfiability Testin

    Implementation status of mandatory inspection of sprayers in Romania

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    To harmonize the Romanian legislation on plant protection to the European legislation the Directive 128/2009 has been transposed into national legislation by Government Emergency Ordinance 34/2012 on establishing the institutional framework for action to the sustainable use of pesticides in Romania.National Action Plan approved by Decision 683/2013, on reducing the risks associated with the use of plant protection products is the strategic document regarding the continuous improvement of the use of plant protection products and contains quantitative targets, measures and timetables to reduce risks and the effects of using plant protection products on the environment and human health

    Tracing the origin of the single-spin asymmetries observed in inclusive hadron production processes at high energies

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    It is pointed out that the existing models for the left-right asymmetries observed in single-spin inclusive hadron production processes can be differentiated experimentally. Several such experiments are proposed with which the basic assumptions of these models can be tested individually.Comment: 12 pages, one figur

    An Algorithm for Dualization in Products of Lattices and Its Applications

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    Let \cL=\cL_1×⋅s×\cL_n be the product of n lattices, each of which has a bounded width. Given a subset \cA\subseteq\cL, we show that the problem of extending a given partial list of maximal independent elements of \cA in \cL can be solved in quasi-polynomial time. This result implies, in particular, that the problem of generating all minimal infrequent elements for a database with semi-lattice attributes, and the problem of generating all maximal boxes that contain at most a specified number of points from a given n-dimensional point set, can both be solved in incremental quasi-polynomial time

    Parton Distributions for the Octet and Decuplet Baryons

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    We calculate the parton distributions for both polarized and unpolarized octet and decuplet baryons, using the MIT bag, dressed by mesons. We show that the hyperfine interaction responsible for the Δ−N\Delta - N and Σ0−Λ\Sigma^0 - \Lambda splittings leads to large deviations from SU(3) and SU(6) predictions. For the Λ\Lambda we find significant polarized, non-strange parton distributions which lead to a sizable Λ\Lambda polarization in polarized, semi-inclusive epep scattering. We also discuss the flavour symmetry violation arising from the meson-cloud associated with the chiral structure of baryons.Comment: 29 pages, 15 figure

    Quark Distributions of Octet Baryons from SU(3) Symmetry

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    SU(3) symmetry relations between the octet baryons are introduced in order to connect both the unpolarized and polarized quark distributions of the octet baryons with those of the nucleon. Two different parametrizations of the nucleon quark distributions are used. A new scenario of quark flavor and spin structure of the Λ\Lambda is found and compared with two other models: a perturbative QCD based analysis and a quark diquark model. The uu and dd quarks inside the Λ\Lambda are predicted to be positively polarized at large Bjorken variable xx in the new scenario. By using an approximate relation connecting the quark fragmentation functions with the quark distributions, the hadron polarizations of the octet baryons in e+e−e^+e^--annihilation, polarized charged lepton deep inelastic scattering (DIS) processes, and neutrino (antineutrino) DIS processes are predicted. The predictions for Λ\Lambda polarizations in several processes are compatible with the available data at large fragmentation momentum fraction zz, and support the prediction of positively polarized uu and dd quarks inside the Λ\Lambda at large xx. Predictions for Drell-Yan processes from Σ±\Sigma^{\pm} and Ξ−\Xi^- beams on an isoscalar target are also given and discussed.Comment: 29 latex pages, 16 figures, to appear in PR
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