离散时间Geo~(λ_1,λ_2)/G/1(ES,MV)排队系统离去过程的分解

考虑顾客到达率可变的多重休假Geo/G/1排队系统的离去过程.运用全概率分解,更新过程理论和u-变换,讨论了从任意初始状态出发,在(0⁺,n+,n⁺]中离去顾客的平均数,得到系统在(0+]中离去顾客的平均数,得到系统在(0⁺,n+,n⁺]中离去顾客平均数的瞬态分解表达式,以及其稳态分解结果.揭示了系统离去更新过程的特殊结构:离去更新过程被分解为两部分,一部分是系统服务状态(忙,闲)过程,另一部分是忙期中的服务更新过程,从而简化了对离去过程的研究.在排队网络中,由于一个排队系统的输出即为下游排队系统的输入,因此,本文所得结果对研究排队网络有重要意义.     

多级适应性休假MX/G/1排队系统的离去过程

考虑多级适应性休假的M~X/G/1排队系统的离去过程.运用全概率分解,更新过程理论和拉普拉斯-斯蒂尔吉变换,讨论了从初始状态i(i=0,1,…)出发,在(0,t]中服务完顾客的平均数,揭示了离去过程的特殊结构,并由此得到了一些特殊排队模型的相应指标.     

具有单重休假和Min(N,V)-策略控制的Geo/G/1离散时间排队的离去过程分析

该文研究服务员具有单重休假和系统采用Min(N,V)-策略控制的Geo/G/1离散时间排队系统的离去过程.首先,借助全概率分解方法,更新过程理论以及概率母函数技术,讨论了服务员在任意时刻点n~+处于忙的瞬态概率和稳态概率.其次,得到了在时间段(0~+,n~+]内的平均离去顾客数的概率母函数表达式.同时给出了离去过程、服务员忙的状态过程和在服务员忙期中的服务更新过程三者之间的关系,这一关系表明了系统离去过程的特殊结构.特别地,直接获得了一些特殊离散时间排队系统的离去过程的相应结果.最后,给出了便于计算任意时间段(0~+,n~+]内平均离去顾客数的渐近展式.     

Geometric／G／1休假随机服务系统

本文讨论服务员休假的离散时间Geonletric/G/1排队系统。在多级适应性休假规则下,给出稳态队长、等待时间的分布和随机分解,也研究了忙期、全假期、在线期的分布。多重休假、单重休假、启动时间规则,都是本文中模型的特例。     

带两类服务的一般休假M/GI/1型系统的随机分解

借助于建立在平稳点过程和Palm分布理论基础上的强度保守原理,讨论了一个具有一般休假策略的M/GI/1型排队系统.该模型允许闲期中顾客非泊松到达且顾客的服务可以被休假中断。我们得到了稳态下工作量和顾客离去前所见队长的随机分解.     

异步休假M／M／C排队的稳态理论

本文研究异步休假的M／M／c排队,对多重休假和单重休假两类模型给出了统一的处理,得到了稳态队长,等等时间分布,提出了条件的随机分解的概念,证明服务台全忙条件下系统中排队顾客数和等待时间均可分解为两个独立随机变量之和,其中一个是经典无休假系统中对应的条件随机变量。     

具有可变到达率的多重休假Geo~(λ_1,λ_2)/G/1排队分析

本文考虑顾客到达与服务员休假相关的多重休假离散时间排队系统,用更新过程及u-变换分析了系统的队长性质.分别得到系统在三种时点(n~-,n~+,n)处的队长分布的递推解,进而揭示了在不同到达率条件下系统队长分布不再具有随机分解特性,得到了系统在四种时点(n~-,n~+,n,离去时点D_n)处稳态队长分布的重要关系(不同于连续时间排队系统).     

同步休假GI／M／c排队的稳态理论

本文研究同步多重休假的GI／M／c排队系统,休假时间服从指数分布,使用发展了矩阵几何解决方法,给出了系统的平衡条件、稳态队长及等等时间分布。证明了队长和等等时间的条件随机分解定理,并讨论了由休假引起的附加队长和附加延迟的位相（PH）结构。     

一类休假排队平稳队长分布的无限位相表示

讨论休假时间服从T-SPH分布的M/M/1单重休假模型,其中T-SPH表示可数状态吸收生灭过程吸收时间的分布.该排队模型可以用可数位相拟生灭过程(QBD过程)和算子几何解的方法进行建模分析.首先得到了QBD过程算子几何解的具体形式;其次在所得结果的基础上,进一步给出了排队模型平稳队长的随机分解结果,并说明附加队长服从离散时间无限位相分布.     

延迟Min(N,D)-策略下M/G/1排队系统的离去过程

考虑延迟Min(N, D)-策略下M/G/1排队系统的离去过程.运用全概率分解技术、更新过程理论和Laplace-Stieltjes变换,从任意初始状态出发,讨论在有限区间(0, t]内离去顾客的平均数,给出了离去过程、服务员状态过程和服务员忙期中的服务更新过程之间的关系,该关系揭示了离去过程的随机分解特性,并得到了离去顾客平均数的渐近展开式.在排队网络中,由于一个排队系统的输出即为下游排队系统的输入,希望本文所得结果为排队网络的研究提供有用的信息.     

Proof of the impossibility of the fermat equation Xp + Yp = Zp for special values of p and of the more general equation bXn + cYn = dZn

This paper continues the search to determine for what exponents n Fermat's Last Theorem is true. The main theorem and Corollary 1 consider the set of prime exponents p for which mp + 1 is prime for certain even integers m and prove the truth of FLT in Case 1 for such primes p. The remaining theorems prove the inequality of the more general Fermat equation bXⁿ + cYⁿ = dZⁿ.     

Enumeration of the BranchedmZp-Coverings of Closed Surfaces

In this paper, we enumerate the equivalence classes of regular branched coverings of surfaces whose covering transformation groups are the direct sum of m copies of Z_p, p prime.     

Dimension of the crown Skn

In 1941, Dushnik and Miller introduced the concept of the dimension of a poset (X, P) as the minimum number of linear extensions of P whose intersection is exactly P. Although Dilworth has given a formula for the dimension of distributive lattices, the general problem of determining the dimension of a poset is quite difficult. An equally difficult problem is to classify those posets which are dimension irreducible, i.e., those posets for which the removal of any point lowers the dimension. In this paper, we construct for each n≥3, k≥0, a poset, called a crown and denoted S^k_n, for which the dimension is given by the formula $\text{2?(n+k)}\text{(k+2)}$. Furthermore, for each t≥3, we show that there are infinitely many crowns which are irreducible and have dimension t. We then demonstrate a method of combining a collection of irreducible crowns to form an irreducible poset whose dimension is the sum of the crowns in the collection. Finally, we construct some infinite crowns possessing combinatorial properties similar to finite crowns.     

Approximation of M/M/s/K retrial queue with nonpersistent customers

We consider the M/M/s/K retrial queues in which a customer who is blocked to enter the service facility may leave the system with a probability that depends on the number of attempts of the customer to enter the service facility. Approximation formulae for the distributions of the number of customers in service facility, waiting time in the system and the number of retrials made by a customer during its waiting time are derived. Approximation results are compared with the simulation.     

Constructions of partitions of FqN into perfect q-ary codes

Given N = (q ^m − 1)/(q − 1), where q is a power of a prime, q > 2, we present two constructions of different partitions of the set F _q ^N of all q-ary length N vectors into perfect q-ary codes of length N. The lower bounds on the number of these partitions are presented.     

Asymptotic behaviour of the loss probability of theM/G/1/K andG/M/1/K queues

This paper investigates the asymptotic behaviour of the loss probability of theM / G/1/K and G/M/1/K queues as the buffer size increases. It is shown that the loss probability approaches its limiting value, which depends on the offered load, with an exponential decay in essentially all cases. The value of the decay rate can be easily computed from the main queue parameters. Moreover, the close relation existing between the loss behaviour of the two examined queueing systems is highlighted and a duality concept is introduced. Finally some numerical examples are given to illustrate on the usefulness of the asymptotic approximation.     

Automorphisms of Chevalley groups of types Al, Dl, El over local rings without 1/2

In this paper, we prove that every automorphism of a Chevalley group of type B _l , l ≥ 2, over a commutative local ring with 1/2 is standard, i.e., it is a composition of ring, inner, and central automorphisms.     

On the asymptotic behavior of xn+1=anxn/xn−1

We investigate the asymptotic behavior of solutions of a separable difference equation of the form

     

Resolvable decomposition of Kn1

In this paper, we prove that $\text{K}{}_{\mathrm{n}}{}^1$ admits a resolvable decomposition into TT₃ or C₃ if and only if n ≡ 0 (mod. 3), n ≠ 6.     

Almost resolvable decomposition of Kn1

In this paper, we show that the complete symmetric directed graph with n vertices $\text{K}{}_{\mathrm{n}}{}^1$ admits an almost resolvable decomposition into TT₃ (the transitive tournament on 3 vertices) or C₃ (the directed cycle of length 3) if and only if n ≡ 1(mod 3).