531,722 research outputs found

    The Proposal of Marketing Management of Software Company

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    Bakalářská práce analyzuje současnou marketingovou strategii pro zvolenou firmu AKI-Sport s.r.o.. Zjištěné výsledky jsou vyhodnoceny a na jejich základě jsou formulována doporučení. Ta by měla vést ke zlepšení stabilního postavení firmy.This bachelor´s thesis has analysed current strategy of company AKI-Sport s.r.o.. Main objective was to search and classify parts of the strategy and based on this research to formulate proper recommendations. All recommended steps would have positive and straight impact on improvements of company solid position.

    Karpi\'nska's paradox in dimension three

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    For 0 < c < 1/e the Julia set of f(z) = c exp(z) is an uncountable union of pairwise disjoint simple curves tending to infinity [Devaney and Krych 1984], the Hausdorff dimension of this set is two [McMullen 1987], but the set of curves without endpoints has Hausdorff dimension one [Karpinska 1999]. We show that these results have three-dimensional analogues when the exponential function is replaced by a quasiregular self-map of three-space introduced by Zorich.Comment: 21 page

    Discrete symmetries, roots of unity, and lepton mixing

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    We investigate the possibility that the first column of the lepton mixing matrix U is given by u_1 = (2,-1,-1)^T/sqrt{6}. In a purely group-theoretical approach, based on residual symmetries in the charged-lepton and neutrino sectors and on a theorem on vanishing sums of roots of unity, we discuss the finite groups which can enforce this. Assuming that there is only one residual symmetry in the Majorana neutrino mass matrix, we find the almost unique solution Z_q x S_4 where the cyclic factor Z_q with q = 1,2,3,... is irrelevant for obtaining u_1 in U. Our discussion also provides a natural mechanism for achieving this goal. Finally, barring vacuum alignment, we realize this mechanism in a class of renormalizable models.Comment: 16 pages, no figures. Erroneous theorem 1 replaced by a theorem of Conway and Jones, appendix A extended, conclusions unchange

    Rare Event Simulation and Splitting for Discontinuous Random Variables

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    Multilevel Splitting methods, also called Sequential Monte-Carlo or \emph{Subset Simulation}, are widely used methods for estimating extreme probabilities of the form P[S(U)>q]P[S(\mathbf{U}) > q] where SS is a deterministic real-valued function and U\mathbf{U} can be a random finite- or infinite-dimensional vector. Very often, X:=S(U)X := S(\mathbf{U}) is supposed to be a continuous random variable and a lot of theoretical results on the statistical behaviour of the estimator are now derived with this hypothesis. However, as soon as some threshold effect appears in SS and/or U\mathbf{U} is discrete or mixed discrete/continuous this assumption does not hold any more and the estimator is not consistent. In this paper, we study the impact of discontinuities in the \emph{cdf} of XX and present three unbiased \emph{corrected} estimators to handle them. These estimators do not require to know in advance if XX is actually discontinuous or not and become all equal if XX is continuous. Especially, one of them has the same statistical properties in any case. Efficiency is shown on a 2-D diffusive process as well as on the \emph{Boolean SATisfiability problem} (SAT).Comment: 16 pages (12 + Appendix 4 pages), 6 figure

    Reverse Engineering Approach to Quantum Electrodynamics

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    The S matrix of e--e scattering has the structure of a projection operator that projects incoming separable product states onto entangled two-electron states. In this projection operator the empirical value of the fine-structure constant alpha acts as a normalization factor. When the structure of the two-particle state space is known, a theoretical value of the normalization factor can be calculated. For an irreducible two-particle representation of the Poincare group, the calculated normalization factor matches Wyler's semi-empirical formula for the fine-structure constant alpha. The empirical value of alpha, therefore, provides experimental evidence that the state space of two interacting electrons belongs to an irreducible two-particle representation of the Poincare group.Comment: 12 pages, minor change
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