共查询到20条相似文献,搜索用时 15 毫秒
1.
И. О. Крaснобaев 《Analysis Mathematica》2012,38(3):187-202
A necessary condition is obtained for the completeness of the system of exponents $$e(\Lambda ) = \left\{ {e^{ - \lambda _n t} :\lambda _n \in \left\{ {z:0 < \operatorname{Re} z < A \in \mathbb{R}^ + ,0 < \operatorname{Im} z < 2\pi } \right\}} \right\}$$ in the space of square integrable functions with the power weight t ?? , where ?1 < ?? < 0. 相似文献
2.
《中学生数学》2006,(22)
Sketches and diagrams are sometimes useful in problem solving.For example,four runners are in a one-mile race:A,B,C,and D.Points are awarded only to the person finishing first or sec- ond.The first-place winner gets more points than the second-place winner.How many different arrangements of first-and second-place winner are possible? 相似文献
3.
C. Năstăsescu B. Torrecillas F. Van Oystaeyen 《Algebras and Representation Theory》2008,11(2):179-190
Let C be a coalgebra over a field k. The aim of this paper is to study the following problem : (P) If C is a k-coalgebra such that C is a generator for the category of left comodules, is C a left quasi-co-Frobenius coalgebra ? The converse always holds. We show that if C has a finite coradical series, the answer is positive. 相似文献
4.
Bernt Øksendal 《Journal of Theoretical Probability》1990,3(2):207-226
We give necessary and sufficient conditions that a time change of ann-dimensional Ito stochastic integralX
t of the form
相似文献
5.
A generalization is a statement that is true about many instances.The following story is aboutmaking a generalization.Francie lives in Phoenix.She has a telephone in her room.She pays for all long-distance callsshe makes.One Sunday she called her cousin Meg in San Diego.As they talked,Francie forgot 相似文献
6.
《Computational Geometry》2014,47(2):316-328
We introduce the problem of draining water (or balls representing water drops) out of a punctured polygon (or a polyhedron) by rotating the shape. For 2D polygons, we obtain combinatorial bounds on the number of holes needed, both for arbitrary polygons and for special classes of polygons. We detail an algorithm that finds the minimum number of holes needed for a given polygon, and argue that the complexity remains polynomial for polyhedra in 3D. We make a start at characterizing the 1-drainable shapes, those that only need one hole. 相似文献
7.
A. N. Khisamiev 《Siberian Mathematical Journal》2012,53(3):551-553
We obtain a sufficient condition for the absence of any universal ??-function in an admissible set (a hereditarily finite admissible set). We construct a tree T of height 4 such that no universal ??-function exists in the hereditarily finite admissible set ? $\mathbb{F} $ (T) over T. 相似文献
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For a hyperbolic α-stable process in the hyperbolic space \(\mathbb {H}^{d}, d\ge 2\), we prove that the mean exit time from a halfspace \(H(a)=\{x_{d}>a\}\subset \mathbb {H}^{d} \) is equal to \(\mathbb {E}^{x} \tau _{H(a)} = c(\alpha , d) \delta ^{\alpha /2}_{H(a)} (x),\) where δD(x) is the (hyperbolic) distance of x to Dc. Based on this exact result we provide a sharp estimate of the mean exit time from a hyperbolic ball B(x0,R) of radius R and center x0: \(\mathbb {E}^{x}\tau _{B(x_{0},R)}\approx (\delta _{B(x_{0},R)}(x) \tanh R)^{\alpha /2}, x\in \mathbb {H}^{d}\). By usual isomorphism argument the same estimate holds in any other model of real hyperbolic space. 相似文献
10.
Let F={H1,...,Hk}(k> 1) be a family of graphs.The Turán number of the family F is the maximum number of edges in an n-vertex {H1,...,Hk)-free graph,denoted by ex(n,F) or ex(n,{H1,H2,...,Hk}).The blow-up of a graph H is the graph obtained from H by replacing each edge in H by a clique of the same size where the new vertices of the cliques are all different.In this paper we determine the Turán number of the family cons... 相似文献
11.
In the equation of viscoelasticity related to a geometric cylinder, we recover the spatial part p of a factorized Lamé kernel depending on two spatial sectional variables. More explicitly, we determine sufficient conditions on the data ensuring the (local) uniqueness of p and its continuous dependence on the data in suitable metrics. 相似文献
12.
由绝对值的定义,公式√a2=|a|可表示为√a2=|a|=a a≥0,-a a〈0.这里a可表示一个数,也可以表一个式子. 相似文献
13.
《Mathematical Modelling》1987,8(8):625-629
A four-state, ergodic Markov chain is used to model a T-junction on a narrow, two-lane, major road. The states are defined more realistically than by previous authors. A formula is obtained for the proportion of traffic configurations in which cars travelling one way are brought to a halt by those turning left onto the minor road. This formula is obtained as a function of four parameters: the mean traffic flows in each direction, the probability that a car on the major road will turn left at the junction and the minimum time gap, in the oncoming flow of traffic, which that manouevre requires. If this proportion is higher than is deemed acceptable, then a left-turn is needed. 相似文献
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Craig DeLancey 《Metaphysica》2011,12(2):87-100
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设a,b∈R~ 且a>b,讨论并比较a/b与a 2b/a b的大小。原题中含有两个变元a、b,为使问题化繁为简,引进新的变元t,且令t=a/b,显然有t>l,则(a 2b)/(a b)=(t 2)/(t 1)>1,这样,要讨论的两个分式的大小比较就转化为讨论t与(t 2)/(t 1)的大小比较了。 1°设t=t 2/t 1,则有t~2 t=t 2t~2=2,由 相似文献
17.
In this paper, we apply a sequential game to study the possibility of ‘contracts’ (or at least mutually beneficial arrangements) between a government and a terrorist group. We find equilibrium solutions for complete and incomplete information models, where the government defends and/or provides positive rent, and the terrorist group attacks. We also study the sensitivities of equilibria as a function of both players’ target valuations and preferences for rent. The contract option, if successful, may achieve (partial) attack deterrence, and significantly increase the payoffs not only for the government, but also for some types of terrorist groups. Our work thus provides some novel insights in combating terrorism. 相似文献
18.
OnaSingularDirichletProblemwithaConvectionTermZhangZhijun(张志军)(Dept.ofMath.andInfor.Science,YantaiUniv.,Yantai,Shangdong,2640... 相似文献
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Cun-Hua Zhang Xiang-Ping Yan Guo-Hu Cui 《Nonlinear Analysis: Real World Applications》2010,11(5):4141-4153
A delayed Lotka–Volterra two-species predator–prey system with discrete hunting delay and distributed maturation delay for the predator population described by an integral with a strong delay kernel is considered. By linearizing the system at the positive equilibrium and analyzing the associated characteristic equation, the asymptotic stability of the positive equilibrium is investigated and Hopf bifurcations are demonstrated. It is found that under suitable conditions on the parameters the positive equilibrium is asymptotically stable when the hunting delay is less than a certain critical value and unstable when the hunting delay is greater than this critical value. Meanwhile, according to the Hopf bifurcation theorem for functional differential equations (FDEs), we find that the system can also undergo a Hopf bifurcation of nonconstant periodic solution at the positive equilibrium when the hunting delay crosses through a sequence of critical values. In particular, by applying the normal form theory and the center manifold reduction for FDEs, an explicit algorithm determining the direction of Hopf bifurcations and the stability of bifurcating periodic solutions occurring through Hopf bifurcations is given. Finally, to verify our theoretical predictions, some numerical simulations are also included at the end of this paper. 相似文献
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