共查询到20条相似文献,搜索用时 546 毫秒
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Zhuang He 《Journal of Pure and Applied Algebra》2019,223(10):4426-4445
For every , we find a sufficient condition for the blow-up of a weighted projective space at the identity point not to be a Mori Dream Space. We exhibit several infinite sequences of weights satisfying this condition in all dimensions . 相似文献
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Let be the finite field of order q. Let G be one of the three groups , or and let W be the standard n-dimensional representation of G. For non-negative integers m and d we let denote the representation of G given by the direct sum of m vectors and d covectors. We exhibit a minimal set of homogeneous invariant polynomials such that for all cases except when and or . 相似文献
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《Discrete Mathematics》2022,345(9):112977
Consider functions , where A and C are disjoint finite sets. The weakly connected components of the digraph of such a function are cycles of rooted trees, as in random mappings, and isolated rooted trees. Let and . When a function is chosen from all possibilities uniformly at random, then we find the following limiting behaviour as . If , then the size of the maximal mapping component goes to infinity almost surely; if , a constant, then process counting numbers of mapping components of different sizes converges; if , then the number of mapping components converges to 0 in probability. We get estimates on the size of the largest tree component which are of order when and constant when , . These results are similar to ones obtained previously for random injections, for which the weakly connected components are cycles and linear trees. 相似文献
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《Discrete Mathematics》2022,345(10):113001
The linked double star , where , is the graph consisting of the union of two stars and with a path on c vertices joining the centers. Its Ramsey number is the smallest integer r such that every 2-coloring of the edges of a admits a monochromatic . In this paper, we study the Ramsey numbers of linked double stars when c is odd. In particular, we establish bounds on the value of and determine the exact value of if , or if and . 相似文献
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《Discrete Mathematics》2022,345(10):113004
Let G be a graph. We say that G is perfectly divisible if for each induced subgraph H of G, can be partitioned into A and B such that is perfect and . We use and to denote a path and a cycle on t vertices, respectively. For two disjoint graphs and , we use to denote the graph with vertex set and edge set , and use to denote the graph with vertex set and edge set . In this paper, we prove that (i) -free graphs are perfectly divisible, (ii) if G is -free with , (iii) if G is -free, and (iv) if G is -free. 相似文献
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Hanan Aljubran Maxim L. Yattselev 《Journal of Mathematical Analysis and Applications》2019,469(1):428-446
Let be a sequence of orthonormal polynomials on the unit circle with respect to a positive Borel measure μ that is symmetric with respect to conjugation. We study asymptotic behavior of the expected number of real zeros, say , of random polynomials where are i.i.d. standard Gaussian random variables. When μ is the acrlength measure such polynomials are called Kac polynomials and it was shown by Wilkins that admits an asymptotic expansion of the form (Kac himself obtained the leading term of this expansion). In this work we generalize the result of Wilkins to the case where μ is absolutely continuous with respect to arclength measure and its Radon–Nikodym derivative extends to a holomorphic non-vanishing function in some neighborhood of the unit circle. In this case admits an analogous expansion with the coefficients depending on the measure μ for (the leading order term and remain the same). 相似文献