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排序方式: 共有1659条查询结果,搜索用时 31 毫秒
1.
We investigate various groupoids associated to an arbitrary inverse semigroup with zero. We show that the groupoid of filters with respect to the natural partial order is isomorphic to the groupoid of germs arising from the standard action of the inverse semigroup on the space of idempotent filters. We also investigate the restriction of this isomorphism to the groupoid of tight filters and to the groupoid of ultrafilters.  相似文献   
2.
使用Galerkin方法,结合Sobolev空间理论和不等式技巧,给出了广义神经传播方程解的存在唯一性定理,然后利用吸引子存在性定理,采用半群方法证明了方程整体吸引子的存在性.  相似文献   
3.
《Discrete Mathematics》2022,345(7):112898
The Hamming distance ham(u,v) between two equal-length words u, v is the number of positions where u and v differ. The words u and v are said to be conjugates if there exist non-empty words x,y such that u=xy and v=yx. The smallest value ham(xy,yx) can take on is 0, when x and y commute. But, interestingly, the next smallest value ham(xy,yx) can take on is 2 and not 1. In this paper, we consider conjugates u=xy and v=yx where ham(xy,yx)=2. More specifically, we provide an efficient formula to count the number h(n) of length-n words u=xy over a k-letter alphabet that have a conjugate v=yx such that ham(xy,yx)=2. We also provide efficient formulae for other quantities closely related to h(n). Finally, we show that h(n) grows erratically: cubically for n prime, but exponentially for n even.  相似文献   
4.
In this paper we investigate two-point algebraic-geometry codes (AG codes) coming from the Beelen-Montanucci (BM) maximal curve. We study properties of certain two-point Weierstrass semigroups of the curve and use them for determining a lower bound on the minimum distance of such codes. AG codes with better parameters with respect to comparable two-point codes from the Garcia-Güneri-Stichtenoth (GGS) curve are discovered.  相似文献   
5.
We consider a Schrödinger operator L=?d2/dx2+V(x) on R, where V is a real-valued measurable function, and give an explicit and simple characterization of intrinsic ultracontractivity (IU) of the Schrödinger semigroup generated by L for a wide class of potentials. By making use of it, we also give new examples of potentials for which the semigroups satisfy (IU) or non-(IU).  相似文献   
6.
This paper is a survey for development of linear distributed parameter system. At first we point out some questions existing in current study of control theory for the Lp linear system with an unbounded control operator and an unbounded observation operator, such as stabilization problem and observer theory that are closely relevant to state feedback operator. After then we survey briefly some results on relevant problems that are related to solvability of linear differential equations in general Banach space and semigroup perturbations. As a principle, we propose a concept of admissible state feedback operator for system (A, B). Finally we give an existence result of admissible state feedback operators, including semigroup generation and the equivalent conditions of admissibility of state feedback operators, for an Lp well-posed system.  相似文献   
7.
In this paper, we study the piecewise pseudo almost periodicity in distribution for a stochastic process. Using the analytic semigroup theory and fixed point strategy with stochastic analysis theory, we obtain the existence and the exponential stability of piecewise pseudo almost periodic in distribution mild solutions for impulsive partial neutral stochastic functional differential equations under non-Lipschitz conditions. Moreover, an example is given to illustrate the general theorems.  相似文献   
8.
This paper deals with a stochastic system which models the population dynamics of a chemostat including species death rate. On the basis of the theory on Markov semigroup, we demonstrate that the probability densities of the distributions for the solutions are absolutely continuous. The densities will convergence in L1 to an invariant density or weakly convergence to a singular measure under appropriate conditions. We also give the sufficient criteria for extinction exponentially of the species. To be specific, when D1>D and the strength of perturbation is relatively small, we derive a precise threshold for the species survival.  相似文献   
9.
We prove a Desch‐Schappacher type perturbation theorem for strongly continuous and locally equicontinuous one‐parameter semigroups which are defined on a sequentially complete locally convex space.  相似文献   
10.
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