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In this paper we consider functionsf(t), – < t < , which are n times continuously differentiable with a given convex modulus of continuity of the n-th derivative. For a certain class of periodic functions we establish a relationship between upper bounds of the absolute values of a function and its n-th derivative.Translated from Matematicheskie Zametki, Vol. 14, No. 3, pp. 329–338, September, 1973.  相似文献   

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Let C( \mathbbRm ) C\left( {{\mathbb{R}^m}} \right) be the space of bounded and continuous functions x:\mathbbRm ? \mathbbR x:{\mathbb{R}^m} \to \mathbb{R} equipped with the norm
|| x ||C = || x ||C( \mathbbRm ): = sup{ | x(t) |:t ? \mathbbRm } \left\| x \right\|C = {\left\| x \right\|_{C\left( {{\mathbb{R}^m}} \right)}}: = \sup \left\{ {\left| {x(t)} \right|:t \in {\mathbb{R}^m}} \right\}  相似文献   

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Given an n by n matrix A, we look for a set S in the complex plane and positive scalars m and M such that for all functions p bounded and analytic on S and throughout a neighborhood of each eigenvalue of A, the inequalities
m·inf{‖fL(S):f(A)=p(A)}?‖p(A)‖?M·inf{‖fL(S):f(A)=p(A)}  相似文献   

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We study the scattering poles of a compactly supported “black box” perturbations of the Laplacian in Rn, n odd. We prove a sharp upper bound of the counting function N(r) modulo o(rn) in terms of the counting function of the reference operator in the smallest ball around the black box. In the most interesting cases, we prove a bound of the type N(r)?Anrn+o(rn) with an explicit An. We prove that this bound is sharp in a few special spherically symmetric cases where the bound turns into an asymptotic formula.  相似文献   

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Let M=(mij)M=(mij) be a nonnegative irreducible n×nn×n matrix with diagonal entries 0. The largest eigenvalue of M is called the spectral radius of the matrix M  , denoted by ρ(M)ρ(M). In this paper, we give two sharp upper bounds of the spectral radius of matrix M. As corollaries, we give two sharp upper bounds of the distance matrix of a graph.  相似文献   

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Let λ2 be the second largest eigenvalue of a graph. Powers (1988) [4] gave some upper bounds of λ2 for general graphs and bipartite graphs, respectively. Considering that these bounds are not always attainable for connected graphs, we present sharp upper bounds of λ2 for connected graphs and connected bipartite graphs in this paper. Moreover, the extremal graphs are completely characterized.  相似文献   

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Let G be a simple connected graph with n vertices and m edges. The spectral radius ρ(G) of G is the largest eigenvalue of its adjacency matrix. In this paper, we firstly consider the effect on the spectral radius of a graph by removing a vertex, and then as an application of the result, we obtain a new sharp upper bound of ρ(G) which improves some known bounds: If (k?2)(k?3)2m?nk(k?3)2, where k(3kn) is an integer, then ρ(G)2m?n?k+52+2m?2n+94.The equality holds if and only if G is a complete graph Kn or K4?e, where K4?e is the graph obtained from K4 by deleting some edge e.  相似文献   

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In the paper, several known inequalities for characteristic functions are sharpened and several new ones are derived. Proceedings of the XVII Seminar on Stability Problems for Stochastic Models, Kazan, Russia, 1995, Part III.  相似文献   

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For a given finite set of linear functionals we construct functions vanishing on them and give order estimates of their derivatives. We also give their different applications.  相似文献   

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We generalize the result of Davenport on the sum of absolute values of discriminants of integer polynomials of degree three. For the first time, we find the exact upper bound for the number of polynomials with given discriminant in the class of cubic polynomials of bounded height for the whole interval of values of discriminants.  相似文献   

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