共查询到20条相似文献,搜索用时 31 毫秒
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A well-known lemma of Suslin says that for a commutative ring if is unimodular where is monic and , then there exist such that the ideal generated by equals . This lemma played a central role in the resolution of Serre’s Conjecture. In the case where contains a set of cardinality greater than such that is invertible for each in , we prove that the can simply correspond to the elementary operations , , where . These efficient elementary operations enable us to give new and simple algorithms for reducing unimodular rows with entries in to using elementary operations in the case where is an infinite field. Another feature of this paper is that it shows that the concrete local–global principles can produce competitive complexity bounds. 相似文献
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This paper aims at providing an alternative approach to study global dynamic properties for a two-species chemotaxis model, with the main novelty being that both populations mutually compete with the other on account of the Lotka–Volterra dynamics. More precisely, we consider the following Neumann initial–boundary value problem in a bounded domain , with smooth boundary, where are positive constants.When and , it is shown that under some explicit largeness assumptions on the logistic growth coefficients and , the corresponding Neumann initial–boundary value problem possesses a unique global bounded solution which moreover approaches a unique positive homogeneous steady state of above system in the large time limit. The respective decay rate of this convergence is shown to be exponential.When and , if is suitable large, for all sufficiently regular nonnegative initial data and with and , the globally bounded solution of above system will stabilize toward as in algebraic. 相似文献
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Fenglong Sun Lishan Liu Yonghong Wu 《Computers & Mathematics with Applications》2018,75(10):3685-3701
In this paper, we study the initial boundary value problem for a class of parabolic or pseudo-parabolic equations: where , with being the principal eigenvalue for on and . By using the potential well method, Levine’s concavity method and some differential inequality techniques, we obtain the finite time blow-up results provided that the initial energy satisfies three conditions: (i) ; (ii) , where is a nonnegative constant; (iii) , where involves the -norm or -norm of the initial data. We also establish the lower and upper bounds for the blow-up time. In particular, we obtain the existence of certain solutions blowing up in finite time with initial data at the Nehari manifold or at arbitrary energy level. 相似文献
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