共查询到20条相似文献,搜索用时 203 毫秒
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本文主要利用偏序集的同调方法,给出任意两个分层偏序集的等价分类映射概念;证明了该映射是保Cohen-Macaulay性质的。本文的结论部份回答了B.Stechin^[1]的问题,同时推广了词偏序集的Mobius函数的符号交错性。 相似文献
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设R是有1的结合环,I是任意偏序集,RI是R上I的偏序集环.本文考虑了带对偶的偏序集环,得到:RI带Morita对偶当且仅当R带Morita对偶.推广了已有的在R是有限偏序集时的有关结果 相似文献
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本文讨论了树型集上与偏序集上最优停止问题两者间的关系,证明了最优策略与最优控制变量的一一对应关系,从而导出最优策略.可在最优控制变量中取到. 相似文献
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给出定向完备偏序半群的定义,研究定向完备偏序半群在定向完备偏序集上的作用.探讨S-定向完备偏序集范畴的一些基本性质,并且证明以S-定向完备偏序集为对象,以S-Scott连续映射为态射的范畴是笛卡尔闭范畴. 相似文献
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统筹图又叫计划网络图。任给一个其元素叫做工序(或作业或活动)的有限偏序集,要绘制它的一个最优统筹图,限含虚工序数目为最少者,是一个尚未从理论上解决的问题。本文讨论了虚工序产生的原因和如何减少虚工序数量的一些途径;指出了高度为二的编序集其最优统筹图含虚工序数目达到最大且等于该偏序集框图的边数的充分必要条件;本文给出了一个绘制最优统筹图的近似算法,此算法弥补了文[2]和[3]所给算法的一些不足之处。 相似文献
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We study the set of Cohen-Macaulay monomial ideals with a given radical. Among this set of ideals are the so-called Cohen-Macaulay modifications. Not all Cohen-Macaulay squarefree monomial ideals admit nontrivial Cohen-Macaulay modifications. It is shown that if there exists one such modification, then there exist indeed infinitely many. 相似文献
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Nicholas R. Baeth 《Journal of Pure and Applied Algebra》2007,208(3):923-940
This paper determines when the Krull-Schmidt property holds for all finitely generated modules and for maximal Cohen-Macaulay modules over one-dimensional local rings with finite Cohen-Macaulay type. We classify all maximal Cohen-Macaulay modules over these rings, beginning with the complete rings where the Krull-Schmidt property is known to hold. We are then able to determine when the Krull-Schmidt property holds over the non-complete local rings and when we have the weaker property that any two representations of a maximal Cohen-Macaulay module as a direct sum of indecomposables have the same number of indecomposable summands. 相似文献
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We provide the regularity and the Cohen-Macaulay type of binomial edge ideals of Cohen-Macaulay cones,and we show the extremal Betti numbers of some classes of Cohen-Macaulay binomial edge ideals:Cohen-Macaulay bipartite and fan graphs.In addition,we compute the Hilbert-Poincaré series of the binomial edge ideals of some Cohen-Macaulay bipartite graphs. 相似文献
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Jürgen Herzog 《Journal of Combinatorial Theory, Series A》2006,113(5):911-916
We classify all Cohen-Macaulay chordal graphs. In particular, it is shown that a chordal graph is Cohen-Macaulay if and only if it is unmixed. 相似文献
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The aim of this paper is to study homological properties of deficiently extremal Cohen-Macaulay algebras. Eagon-Reiner showed
that the Stanley-Reisner ring of a simplicial complex has a linear resolution if and only if the Alexander dual of the simplicial
complex is Cohen-Macaulay. An extension of a special case of Eagon-Reiner theorem is obtained for deficiently extremal Cohen-Macaulay
Stanley-Reisner rings. 相似文献
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We characterize Cohen-Macaulay and Gorenstein rings obtained from certain types of convex body semigroups. Algorithmic methods to check if a polygonal or circle semigroup is Cohen-Macaulay/Gorenstein are given. We also provide some families of Cohen-Macaulay and Gorenstein rings. 相似文献
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Ragnar-Olaf Buchweitz Graham J. Leuschke Michel Van den Bergh 《Inventiones Mathematicae》2010,182(1):47-115
We show that determinantal varieties defined by maximal minors of a generic matrix have a non-commutative desingularization,
in that we construct a maximal Cohen-Macaulay module over such a variety whose endomorphism ring is Cohen-Macaulay and has
finite global dimension. In the case of the determinant of a square matrix, this gives a non-commutative crepant resolution. 相似文献
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We investigate how to modify a simple graph G combinatorially to obtain a sequentially Cohen-Macaulay graph. We focus on adding configurations of whiskers to G, where to add a whisker one adds a new vertex and an edge connecting this vertex to an existing vertex of G. We give various sufficient conditions and necessary conditions on a subset S of the vertices of G so that the graph G∪W(S), obtained from G by adding a whisker to each vertex in S, is a sequentially Cohen-Macaulay graph. For instance, we show that if S is a vertex cover of G, then G∪W(S) is a sequentially Cohen-Macaulay graph. On the other hand, we show that if G?S is not sequentially Cohen-Macaulay, then G∪W(S) is not a sequentially Cohen-Macaulay graph. Our work is inspired by and generalizes a result of Villarreal on the use of whiskers to get Cohen-Macaulay graphs. 相似文献
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We generalize the results of Kahn about a correspondence between Cohen-Macaulay modules and vector bundles to non-commutative surface singularities. As an application, we give examples of non-commutative surface singularities which are not Cohen-Macaulay finite, but are Cohen-Macaulay tame. 相似文献