1,721,241 research outputs found

    Counting sets with exceptions

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    Let N,E,X,K>0N,E,X,K>0 be integers such that N+E<XN+E<X and Kmin(N,E)K\le\min(N,E). The author proves the inequality (XN)j=0K(XENj)(Ej)(XN)NE(K+1)X,{X\choose N}-\sum_{j=0}^K{X-E\choose N-j}{E\choose j}\le{X\choose N}{NE\over (K+1)X}, where the motivation is that the left-hand side counts those NN-element subsets of an XX-element set SS which intersect a fixed EE-element subset TST\subset S in at least K+1K+1 elements. The inequality is compared with another one of the same sort that was obtained by Brüdern and Perelli

    Factorization in the extended Selberg class of L-functions associated to modular forms

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    Let NNN\in\N and let χ\chi be a Dirichlet character modulo NN. Let ff be a modular form with respect to the group Γ0(N)\Gamma_0(N), multiplier χ\chi and weight kk. Let FF be the LL-function associated with ff and normalized in such a way that F(s)F(s) satisfies a functional equation where ss reflects in 1s1-s. The modular forms ff for which FF belongs to the extended Selberg class \Selberg^\sharp are characterized. For these forms the factorization of FF in primitive elements of \Selberg^\sharp is enquired. In particular, it is proved that if ff is a cusp form and F\in\Selberg^\sharp then FF is almost primitive (i.e., that if F=PGF=PG is a factorization with P,G\in\Selberg^\sharp and the degree of PP is <2<2 then PP is a Dirichlet polynomial). It is also proved that the conductor of the polynomial factor PP is bounded by NN. If ff belongs to the space generated by newforms and N4N\leq 4 then FF is actually primitive (i.e., PP is a constant)

    Upper and lower bounds at s=1 for certain Dirichlet series with Euler product

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    Estimates of the form L(j)(s, script A sign) ≪ε,j,script D sign script A signRεscript A sign in the range |s - 1| ≪ 1/log Rscript A sign for general L-functions, where Rscript A sign, is a parameter related to the functional equation of L(s, script A sign), can be quite easily obtained if the Ramanujan hypothesis is assumed. We prove the same estimates when the L-functions have Euler product of polynomial type and the Ramanujan hypothesis is replaced by a much weaker assumption about the growth of certain elementary symmetrical functions. As a consequence, we obtain an upper bound of this type for every L(s, π), where π is an automorphic cusp form on GL(d, double-struck A signK). We employ these results to obtain Siegel-type lower bounds for twists by Dirichlet characters of the third symmetric power of a Maass form

    Thermal behavior of dipolarophile-containing 2-azidocarbonylpyrroles and -indoles

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    The thermal reaction of N-allyl- or N-propargyl-2-azidocarbonylpyrroles (2) or -indoles (9) involves competition between intramolecular azide cycloaddition and Curtius rearrangement

    Multiplicity results for the functional equation of the Dirichlet LL-functions: case p=2p=2

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    Given an integer q and a primitive character χ modulo q, the functionalequation of the Dirichlet L-function L(s, χ) is determined by the signature of χ, i.e. byχ(−1) (the parity) and τ(χ) (the Gauss sum). In this paper we prove several resultsabout the cardinalities of the sets T(χ) := {ψ : τ(ψ) = τ(χ)} and W(χ) := {ψ : τ(ψ) =τ(χ), ψ(−1) = χ(−1)}, mainly an algorithm for their computation and optimal upperand lower bounds for their values, when q is either an odd prime power or a compositenumber of special form. For the same q we compute also the number of distinct Gausssums and of distinct signatures: the latter number deserves a special attention because itcoincides with the number of non-trivial functional equations of degree 1 and conductorq in the Selberg class

    Multiplicity results for the functional equation of the Dirichlet LL-functions

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    Given an integer qq and a primitive character χ\chi modulo qq, the functional equation of the Dirichlet LL-function L(s,χ)L(s,\chi) is determined by the \emph{signature} of χ\chi, i.e. by χ(1)\chi(-1) (the parity) and τ(χ)\tau(\chi) (the Gauss sum). In this paper we prove several results about the cardinalities of the sets T(χ):={ψ:τ(ψ)=τ(χ)}T(\chi):=\{\psi:\,\tau(\psi)=\tau(\chi)\} and W(χ):={ψ:τ(ψ)=τ(χ), ψ(1)=χ(1)}W(\chi):=\{\psi:\,\tau(\psi) = \tau(\chi),\ \psi(-1)=\chi(-1)\}, mainly an algorithm for their computation and optimal upper and lower bounds for their values, when qq is either an odd prime power or a composite number of special form. For the same qq we compute also the number of distinct Gauss sums and of distinct signatures: the latter number deserves a special attention because it coincides with the number of non-trivial functional equations of degree 11 and conductor qq in the Selberg class

    Explicit bounds for even moments of Bernstein's polynomials

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    We prove explicit and optimal lower and upper bounds for even-order moments of Bernstein polynomials

    The first case of diastereoselective cycloadditions of enantiopure nitrilimines in aqueous media

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    The diastereoselective cycloadditions of enantiopure nitrilimines 4 with ethyl acrylate were exploited in dry toluene and in aqueous sodium hydrogencarbonate as reaction media. Shorter reaction times and improved diastereoisomeric ratios of the resulting 5-ethoxycarbonyl-4,5-dihydropyrazoles 5 and 6 were observed in aqueous media

    An explicit bound for the error term of the development at s=1 of a set of lacunary series

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    An explicit bound for the error term of the expansion of Fn(x):=k=0knx2kF_n(x):=\sum_{k=0}^\infty k^nx^{2^k} as x1x\to 1^- is given
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