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971.
Peter Vermeire 《Journal of Pure and Applied Algebra》2009,213(6):1129-1132
We give positivity conditions on the embedding of a smooth variety which guarantee the normality of the secant variety, generalizing earlier results of the author and others. We also give classes of secant varieties satisfying the Hodge conjecture as well as a result on the singular locus of degenerate secant varieties. 相似文献
972.
Jorge Almeida 《Journal of Pure and Applied Algebra》2009,213(5):605-631
Some fundamental questions about infinite-vertex (free) profinite semigroupoids are clarified, putting in evidence differences with the finite-vertex case. This is done with examples of free profinite semigroupoids generated by the graph of a subshift. It is also proved that for minimal subshifts, the infinite edges of such free profinite semigroupoids form a connected compact groupoid. 相似文献
973.
We construct local-to-global spectral sequences for the cohomology of a diagram, which compute the cohomology of the full diagram in terms of smaller pieces. These are motivated by the obstruction theory of D. Blanc et al. [D. Blanc, M.W. Johnson, J.M. Turner, On realizing diagrams of Π-algebras, Algebraic Geom. Topol. 6 (2006) 763-807] for realizing a diagram of Π-algebras, but are valid in quite general algebraic settings. 相似文献
974.
Mark Wildon 《Journal of Pure and Applied Algebra》2009,213(7):1464-1477
Building on work of Saxl, we classify the multiplicity-free permutation characters of all symmetric groups of degree 66 or more. A corollary is a complete list of the irreducible characters of symmetric groups (again of degree 66 or more) which may appear in a multiplicity-free permutation representation. The multiplicity-free characters in a related family of monomial characters are also classified. We end by investigating a consequence of these results for Specht filtrations of permutation modules defined over fields of prime characteristic. 相似文献
975.
Duong Quoc Viet 《Journal of Pure and Applied Algebra》2009,213(11):2104-2116
Let A be a Noetherian local ring with the maximal ideal m and an m-primary ideal J. Let S=?n≥0Sn be a finitely generated standard graded algebra over A. Set S+=?n>0Sn. Denote by FJ(S)=?n≥0→(Sn/JSn) the fiber cone of S with respect to J. The paper characterizes the multiplicity and the Cohen-Macaulayness of FJ(S) in terms of minimal reductions of S+. 相似文献
976.
We introduce a notion of Gorenstein algebras of codimension c and demonstrate that Serre duality theory plays an essential role in the theory of derived equivalences for Gorenstein algebras. 相似文献
977.
K.Q. Lan 《Journal of Differential Equations》2009,246(3):909-530
A variational inequality theory for demicontinuous S-contractive maps in Hilbert spaces is established by employing the ideas of Granas' topological transversality. Such a variational inequality theory has many properties similar to those of fixed point theory for demicontinuous weakly inward S-contractive maps and to those of fixed point index for condensing maps. The variational inequality theory will be applied to study the existence of positive weak solutions and eigenvalue problems for semilinear second-order elliptic inequalities with nonlinearities which satisfy suitable lower bound conditions involving the critical Sobolev exponent. There has been little discussion for such elliptic inequalities involving the critical Sobolev exponent in the literature. 相似文献
978.
Bixiang Wang 《Journal of Differential Equations》2009,246(6):2506-172
We prove the existence of a compact random attractor for the stochastic Benjamin-Bona-Mahony equation defined on an unbounded domain. This random attractor is invariant and attracts every pulled-back tempered random set under the forward flow. The asymptotic compactness of the random dynamical system is established by a tail-estimates method, which shows that the solutions are uniformly asymptotically small when space and time variables approach infinity. 相似文献
979.
For a general class of divergence type quasi-linear degenerate parabolic equations with measurable coefficients and lower order terms from nonlinear Kato-type classes, we prove local boundedness and continuity of solutions, and the intrinsic Harnack inequality for positive solutions. 相似文献
980.
针对震后次生灾害的演化问题,本文采用多案例分析方法提取地震及其次生灾害事件的属性,从属性层次按照“事件类型、关键属性、从属属性、环境属性和危害评估属性”对其进行结构化描述,分析震后次生灾害事件的属性特征,绘出了震后次生灾害演化Petri网模型。在此基础上,以渐变型次生灾害事件——震后瘟疫为例,根据随机Petri网与马尔科夫链的同构关系,构建了震后瘟疫事件演化系统随机Petri网模型。最后,通过马尔科夫链及相关数学方法对震后瘟疫事件演化系统进行了评估,分析其中的均衡状态及其变动规律,验证了模型的有效性,为应对地震次生灾害事件提供科学的应急决策支持。 相似文献