共查询到20条相似文献,搜索用时 78 毫秒
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基于遗传算法的大学课程表问题研究 总被引:3,自引:0,他引:3
课程表问题是时间表问题之一 ,也是 NP难问题 .根据大学授课形式的特点建立了大学课程表问题的数学模型 ,给出了求解该问题的遗传算法 .根据模型和大学课程表问题的特点设计了一种全新的编码 ,提出了一种新形式的交叉方式 .实验结果表明该方法是可行和有效的 . 相似文献
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崔春生 《数学的实践与认识》2014,(8)
从目前研究生入学考试中出现的几种新的运筹学运输问题出发,探讨了各种运输问题与传统运输问题的差异。提出以传统运输问题为本,将非传统运输问题转化为传统运输问题借助表上作业法求解的思路。并针对6种不同的非传统运输问题分析了转化的过程和步骤,为运输问题的研究提供了新的内容. 相似文献
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一类非光滑规划问题的最优性和对偶 总被引:1,自引:1,他引:0
研究一类非光滑多目标规划问题,给出了该规划问题的三个最优性充分条件.同时,研究了该问题的对偶问题,给出了相应的弱对偶定理和强对偶定理. 相似文献
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上模集函数的优化问题在组合优化问题中有广泛应用,许多组合优化问题,如设备选址问题、p-中心问题等都可化为上模集函数的优化问题.本文给出了求解非减上模集函数最小值问题的一种近似算法,并讨论了所给算法的性能保证. 相似文献
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Wenbin Guo 《代数通讯》2013,41(10):4767-4782
This paper answers the open question 12.73 in “Unsolved Problems in Group Theory, The Kourovka Notebook, 1995“. This paper give an example to show that this question has a negative solution, and give a condition under which the conclusion of the question is correct. 相似文献
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M. V. Prasolov 《Mathematical Notes》2011,89(3-4):545-554
In [1, Open question 2], the following question was posed: Is the size of the ultra summit set of the conjugacy class of a rigid pseudo-Anosov braid bounded above by a polynomial in the braid length and the number of strands? A negative answer to this question is given. 相似文献
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One of the longstanding problems in universal algebra is the question of which finite lattices are isomorphic to the congruence lattices of finite algebras. This question can be phrased as which finite lattices can be represented as lattices of equivalence relations on finite sets closed under certain first-order formulas. We generalize this question to a different collection of first-order formulas, giving examples to demonstrate that our new question is distinct. We then note that every lattice M n can be represented in this new way. 相似文献
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We prove that a countably compact space is monotonically retractable if and only if it has a full retractional skeleton. In particular, a compact space is monotonically retractable if and only if it is Corson. This gives an answer to a question of R. Rojas-Hernández and V.V. Tkachuk. Further, we apply this result to characterize retractional skeleton using a topology on the space of continuous functions, answering thus a question of the first author and a related question of W. Kubi?. 相似文献
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We consider colourings of Steiner systems S(2,3,v) and S(2,4,v) in which blocks have prescribed colour patterns, as a refinement of the classical weak colourings. The main question studied is, given an integer k, does there exist a colouring of given type using exactly k colours? For several types of colourings, a complete answer to this question is obtained while for other types, partial results are presented. We also discuss the question of the existence of uncolourable systems. 相似文献
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D. J. Benson 《Algebras and Representation Theory》1999,2(3):287-294
Let k be a commutative ring of coefficients and G be a finite group. Does there exist a flat k G-module which is projective as a k-module but not as a k G-module? We relate this question to the question of existence of a k-module which is flat and periodic but not projective. For either question to have a positive answer, it is at least necessary to have |k| ≥ ?ω. There can be no such example if k is Noetherian of finite Krull dimension, or if k is perfect. 相似文献
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Vasile Lauric 《Czechoslovak Mathematical Journal》2018,68(4):1125-1130
The question whether a hyponormal weighted shift with trace class self-commutator is the compression modulo the Hilbert-Schmidt class of a normal operator, remains open. It is natural to ask whether Putinar’s construction through which he proved that hyponormal operators are subscalar operators provides the answer to the above question. We show that the normal extension provided by Putinar’s theory does not lead to the extension that would provide a positive answer to the question. 相似文献
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非紧超凸度量空间中的Browder不动点定理及其对重合问题的应用 总被引:23,自引:1,他引:22
在非紧超凸度量空间中的非紧允许集上,建立了一个新的Browder不动点定理.作为应用,在非紧超凸度量空间中,研究了Ky Fan截口问题和相交问题,并新建了两个Ky Fan重合定理. 相似文献