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Let be a graph of order . An even squared Hamiltonian cycle (ESHC) of is a Hamiltonian cycle of with chords for all (where for ). When is even, an ESHC contains all bipartite -regular graphs of order . We prove that there is a positive integer such that for every graph of even order , if the minimum degree is , then contains an ESHC. We show that the condition of being even cannot be dropped and the constant cannot be replaced by . Our results can be easily extended to even th powered Hamiltonian cycles for all . 相似文献
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Tomoyuki Nakatsuka 《Nonlinear Analysis: Theory, Methods & Applications》2012,75(8):3457-3464
The aim of this paper is to prove a uniqueness criterion for solutions to the stationary Navier–Stokes equation in 3-dimensional exterior domains within the class with , where and are the Lorentz spaces. Our criterion asserts that if and are the solutions, is small in and for some , then . The proof is based on analysis of the dual equation with the aid of the bootstrap argument. 相似文献
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A note on degree sum conditions for 2-factors with a prescribed number of cycles in bipartite graphs
Let be a balanced bipartite graph of order , and let be the minimum degree sum of two non-adjacent vertices in different partite sets of . In 1963, Moon and Moser proved that if , then is hamiltonian. In this note, we show that if is a positive integer, then the Moon–Moser condition also implies the existence of a 2-factor with exactly cycles for sufficiently large graphs. In order to prove this, we also give a condition for the existence of vertex-disjoint alternating cycles with respect to a chosen perfect matching in . 相似文献
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Let be the n-th harmonic number and let be its denominator. It is well known that is even for every integer . In this paper, we study the properties of . One of our results is: the set of positive integers n such that is divisible by the least common multiple of has density one. In particular, for any positive integer m, the set of positive integers n such that is divisible by m has density one. 相似文献
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《Applied Mathematics Letters》2006,19(8):820-823
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Susan A. van Aardt Christoph Brause Alewyn P. Burger Marietjie Frick Arnfried Kemnitz Ingo Schiermeyer 《Discrete Mathematics》2017,340(11):2673-2677
An edge-coloured graph is called properly connected if any two vertices are connected by a path whose edges are properly coloured. The proper connection number of a connected graph denoted by , is the smallest number of colours that are needed in order to make properly connected. Our main result is the following: Let be a connected graph of order and . If , then except when and where and 相似文献
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A cycle of order is called a -cycle. A non-induced cycle is called a chorded cycle. Let be an integer with . Then a graph of order is chorded pancyclic if contains a chorded -cycle for every integer with . Cream, Gould and Hirohata (Australas. J. Combin. 67 (2017), 463–469) proved that a graph of order satisfying for every pair of nonadjacent vertices , in is chorded pancyclic unless is either or , the Cartesian product of and . They also conjectured that if is Hamiltonian, we can replace the degree sum condition with the weaker density condition
and still guarantee the same conclusion. In this paper, we prove this conjecture by showing that if a graph of order with contains a -cycle, then contains a chorded -cycle, unless and is either or , Then observing that and are exceptions only for , we further relax the density condition for sufficiently large . 相似文献
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Let be a finite group, written multiplicatively. The Davenport constant of is the smallest positive integer such that every sequence of with elements has a non-empty subsequence with product . Let be the Dihedral Group of order and be the Dicyclic Group of order . Zhuang and Gao (2005) showed that and Bass (2007) showed that . In this paper, we give explicit characterizations of all sequences of such that and is free of subsequences whose product is 1, where is equal to or for some . 相似文献