共查询到20条相似文献,搜索用时 15 毫秒
1.
** Email: emelabbasy{at}mans.edu.eg*** Email: shsaker{at}mans.edu.eg In this paper, we consider the discrete non-linear delay populationdynamics model [graphic: see PDF] where m is a positive integer, p(n), Q(n) and (n) are positiveperiodic sequences of period . By the method that involves theapplication of the Gaines and Mawhins coincidence degree theory,we prove that there exists a positive -periodic solution (n). We prove that every positive solutionof (*) which does not oscillate about (n)satisfies limt[y(n)(n)]=0.We establish some necessary and sufficient conditions for theoscillation of every positive solution about (n), and finally, we establish the lower and upperbounds of the oscillatory solutions. 相似文献
2.
Ke Bo Lu 《数学学报(英文版)》2013,29(11):2181-2192
In this paper, we study the combinatorial properties ol words m chscrete dynamical systems from antisymmetric cubic maps. We also discuss the relationship of primitive kneading sequences of length n and period-doubling kneading sequences of length 2n, and then determine the number of all kneading sequences of length n. 相似文献
3.
John E. Franke Abdul-Aziz Yakubu 《Journal of Difference Equations and Applications》2013,19(3):235-249
A discrete multi-species size-structured competition model is considered. By using decreasing growth functions, we achieve the self-regulation of species. We develop various biologically significant conditions for global convergence to the extinction state of the dominated species in the competitive system. With an example we illustrate coexistence in a chaotic supr transient. The chaotic attractor has an unusual pulsating nature. 相似文献
4.
The paper introduces a series of new combinatorial identities which allow one to find the value of the partial sums of some multiple power series. Examples are given of the application of these identities to the summation of infinite series and to the computation of the quantiles of discrete probability distributions.Translated from Matematicheskie Zametki, Vol. 11, No. 1, pp. 121–127, January, 1972. 相似文献
5.
V. K. Leont’ev 《Mathematical Notes》2009,86(3-4):368-372
We present several expressions for generating functions arising in the solution of combinatorial problems related to graph theory and coding theory. 相似文献
6.
Though the VCG auction assumes a central place in the mechanism design literature, there are a number of reasons for favoring Iterative Combinatorial Auctions (ICAs). Several promising ICA formats were developed based on primal–dual and subgradient algorithms. Prices are interpreted as a feasible dual solution and the provisional allocation is interpreted as a feasible primal solution. iBundle(3), dVSV and Ascending Proxy Auction result in VCG payoffs when the coalitional value function satisfies buyer submodularity and bidders bid straightforward, which is an ex-post Nash equilibrium in this case. iBEA and CreditDebit auctions do not even require the buyer submodularity and achieve the same properties for general valuations. Often, however, one cannot assume straightforward bidding and it is not clear from the theory how these non-linear personalized price auctions (NLPPAs) perform in this case. Robustness of auctions with respect to different bidding behavior is a critical issue for any application. We conducted a large number of computational experiments to analyze the performance of NLPPAs with respect to different bidding strategies and valuation models. We compare NLPPAs with the VCG auction and with ICAs with linear prices, such as ALPS and the Combinatorial Clock Auction. While NLPPAs performed very well in case of straightforward bidding, we observe problems with revenue, efficiency, and speed of convergence when bidders deviate. 相似文献
7.
8.
《Quaestiones Mathematicae》2013,36(6):701-715
AbstractThe frame Sc(L) generated by closed sublocales of a locale L is known to be a natural Boolean (“discrete”) extension of a subfit L; also it is known to be its maximal essential extension. In this paper we first show that it is an essential extension of any L and that the maximal essential extensions of L and Sc(L) are isomorphic. The construction Sc is not functorial; this leads to the question of individual liftings of homomorphisms L → M to homomorphisms Sc(L) → Sc(M). This is trivial for Boolean L and easy for a wide class of spatial L, M . Then, we show that one can lift all h : L → 2 for weakly Hausdor? L (and hence the spectra of L and Sc(L) are naturally isomorphic), and finally present liftings of h : L → M for regular L and arbitrary Boolean M. 相似文献
9.
H.L. Abbott 《Discrete Mathematics》1974,9(3):199-204
Let denote an n× n square array of lattice points in the plane let f(n) denote the least number of points that can be selected from such that every point of is visible from at least one of the points selected. It is proved that, for n sufficiently large,. 相似文献
10.
Allan B. Cruse 《Linear algebra and its applications》1977,16(1):65-77
The elements in the group of centrosymmetric n×n permutation matrices are the extreme points of a convex subset of n2-dimensional Euclidean space, which we characterize by a very simple set of linear inequalities, thereby providing an interesting solvable case of a difficult problem posed by L. Mirsky, as well as a new analogue of the famous theorem on doubly stochastic matrices due to G. Birkhoff. Several further theorems of a related nature also are included. 相似文献
11.
12.
13.
14.
We study the behavior of measure-preserving systems with continuous time along sequences of the form {n α}n∈#x2115;} where α is a positive real number1. Let {S t } t∈? be an ergodic continuous measure preserving flow on a probability Lebesgue space (X, β, μ). Among other results we show that:
- For all but countably many α (in particular, for all α∈???) one can find anL ∞-functionf for which the averagesA N (f)(1/N)=Σ n=1 N f(S nα x) fail to converge almost everywhere (the convergence in norm holds for any α!).
- For any non-integer and pairwise distinct numbers α1, α2,..., α k ∈(0, 1) and anyL ∞-functionsf 1,f 2, ...,f k , one has $$\mathop {lim}\limits_{N \to \infty } \left\| {\frac{1}{N}\sum\limits_{n - 1}^N {\prod\limits_{i - 1}^k {f_i (S^{n^{\alpha _i } } x) - \prod\limits_{i - 1}^k {\int_X {f_i d\mu } } } } } \right\|_{L^2 } = 0$$
15.
A discrete time version for models of population dynamics in the presence of an infection 总被引:1,自引:0,他引:1
Giuseppe Izzo Antonia Vecchio 《Journal of Computational and Applied Mathematics》2007,210(1-2):210-221
We present a set of difference equations which represents the discrete counterpart of a large class of continuous model concerning the dynamics of an infection in an organism or in a host population. The limiting behavior of the discrete model is studied and a threshold parameter playing the role of the basic reproduction number is derived. 相似文献
16.
Michel Lassalle 《Annals of Combinatorics》1998,2(1):61-83
We present several combinatorial conjectures related to the expansion of Jack polynomials in terms of power sums. 相似文献
17.
18.
Some combinatorial identities via Fibonacci numbers 总被引:3,自引:0,他引:3
The Pascal matrix and the Stirling matrices of the first kind and the second kind obtained from the Fibonacci matrix are studied, respectively. Also, we obtain combinatorial identities from the matrix representation of the Pascal matrix, the Stirling matrices of the first kind and the second kind and the Fibonacci matrix. 相似文献
19.