How often is a polygon bounded by three sides?

LetL _n be the set of lines (no two parallel) determining ann-sided bounded faceF in the Euclidean plane. We show that the number,f(L _n), of triples fromL _n that determine a triangle containingF satisfies and these bounds are best. This result is generalized tod-dimensional Euclidean space (without the claim that the upper bound is attainable).     

Nonlinear Programming——a Review

Nonlinear programming problems are to minimize general nonlinear functions, possibly subject to some nonlinear constraints. In this paper, we review some recent results on nonlinear optimization.     

随机a—Bloch函数

本文给出了随机幂级数fw(z)∑n=0^∞ane^iwnz^n(其中wn是随机的）属于a-Bloch空间和小a-Bloch空间的条件，推广了Anderson,Clunie和Pommerenke的结果。     

OR—a personal perspective

The occasion of the 60th anniversary of the Journal of the Operational Research Society provides the opportunity for reflection and reminiscing about Operational Research (OR). In this note a personal reflection on the nature of OR is offered. Some ideas are suggested to account for the success and failure of OR and some challenges are noted for its forward progress.     

Stability of a Chem ostatModelfor a Single Specieswith Delayed NutrientRecycling——Case ofWeak KernelFunction

§１．　ＩｎｔｒｏｄｕｃｔｉｏｎＴｈｅｃｏｍｍｏｎｃｈｅｍｏｓｔａｔｍｏｄｅｌｈａｓｂｅｅｎｃｏｎｓｉｄｅｒｅｄｂｙｍａｎｙｍａｔｈｅｍａｔｉａｎｓ（ｓｅｅ［１］）．Ｃｈｅｍｏｓｔａｔｍｏｄｅｌｓｉｎｃｏｒｐｏｒａｔｉｎｇｄｉｓｃｒｅｔｅｔｉｍｅｄｅｌａｙｈａｖｅｂｅｅｎｉｎｖｅｓｔｉｇａｔｅｄｉｎ［２］ａｎｄ［３］．Ｉｎ［４］ａｎｄ［５］，ｃｈｅｍｏｓｔａｔｍｏｄｅｌｓｗｉｔｈｃｏｎｔｉｎｕｏｕｓｔｉｍｅｄｅｌａｙｉｎｎｕｔｒｉｅｎｔｒｅｃｙｃｌｉｎｇｗｅｒｅｃｏｎｓｉｄ－ｅｒｅｄ．Ｉｎｔｈｉ…     

Maintenance of light-standards—a case-study

This paper discusses several strategies for the maintenance of light-standards, where each light-standard consists of n independent and identical lamps screwed on a lamp assembly. The lamps are subject to stochastic failures, and must be correctly replaced if the number of failed lamps reaches a prespecified number m, a norm that is set by the local management to guarantee a minimum luminance. As lamps have an increasing hazard rate and there is a fixed cost of hoisting the assembly, we propose various variants of the m-failure group replacement rule which have in particular an age-criterion to indicate which of the non-failed lamps must be preventively replaced at the time that the assembly is lowered for a corrective lamp replacement. We show how the optimal threshold age can be determined. It appears that this modification reduces the long run average maintenance cost of the Europe Combined Terminals by approximately 8.3%.     

Global Asymptotics of Krawtchouk Polynomials——a Riemann-Hilbert Approach

In this paper, we study the asymptotics of the Krawtchouk polynomials KnN(z;p,q) as the degree n becomes large. Asymptotic expansions are obtained when the ratio of the parameters n/N tends to a limit c∈(0,1) as n→∞. The results are globally valid in one or two regions in the complex z-plane depending on the values of c and p; in particular, they are valid in regions containing the interval on which these polynomials are orthogonal. Our method is based on the Riemann-Hilbert approach introduced by Deift and Zhou.     

Program equilibrium—a program reasoning approach

The concept of program equilibrium, introduced by Howard (Theory and Decision 24(3):203–213, 1988) and further formalised by Tennenholtz (Game Econ Behav 49:363–373, 2004), represents one of the most ingenious and potentially far-reaching applications of ideas from computer science in game theory to date. The basic idea is that a player in a game selects a strategy by entering a program, whose behaviour may be conditioned on the programs submitted by other players. Thus, for example, in the prisoner’s dilemma, a player can enter a program that says “If his program is the same as mine, then I cooperate, otherwise I defect”. It can easily be shown that if such programs are permitted, then rational cooperation is possible even in the one-shot prisoner’s dilemma. In the original proposal of Tennenholtz, comparison between programs was limited to syntactic comparison of program texts. While this approach has some considerable advantages (not the least being computational and semantic simplicity), it also has some important limitations. In this paper, we investigate an approach to program equilibrium in which richer conditions are allowed, based on model checking—one of the most successful approaches to reasoning about programs. We introduce a decision-tree model of strategies, which may be conditioned on strategies of others. We then formulate and investigate a notion of “outcome” for our setting, and investigate the complexity of reasoning about outcomes. We focus on coherent outcomes: outcomes in which every decision by every player is justified by the conditions in his program. We identify a condition under which there exist a unique coherent outcome. We also compare our notion of (coherent) outcome with that of (supported) semantics known from logic programming. We illustrate our approach with many examples.     

诱导的L—fuzzy拓扑空间的a—结构

本文研究Ｌ－ｆｕｚｚｙ拓扑空间的一类几乎开Ｌ－ｆｕｚｚｙ集的性质,在Ｌ－ｆｕｚｚｙ拓扑空间中引入了ａ－结构的概念,证明了由一般拓扑空间（Ｘ,Ｆ）诱导的Ｌ－ｆｕｚｚｙ拓扑空间（Ｌ＾Ｘ,ＷＬ（Ｔ））的ａ－结构必是Ｌ＾Ｘ上的Ｌ－ｆｕｚｚｙ拓扑,并且指出这个拓扑就是由一般拓扑空间（Ｘ,Ｔ）的ａ－结构诱导的,此外,本文还给出了与诱导的Ｌ－ｆｕｚｚｙ拓扑空间的ａ－结构相关的若干性质。     

Tail asymptotics for a generalized two-demand queueing model—a kernel method

In this paper, we consider a generalized two-demand queueing model, the same model studied in Wright (Adv. Appl. Prob., 24, 986–1007, 1992). Using this model, we show how the kernel method can be applied to a two-dimensional queueing system for exact tail asymptotics in the stationary joint distribution and also in the two marginal distributions. We demonstrate in detail how to locate the dominant singularity and how to determine the detailed behavior of the unknown generating function around the dominant singularity for a bivariate kernel, which is much more challenging than the analysis for a one-dimensional kernel. This information is the key for characterizing exact tail asymptotics in terms of asymptotic analysis theory. This approach does not require a determination or presentation of the unknown generating function(s).     

RESEARCH ANNOUNCEMENTS—On a Generalization of the c—numerical Range

Let Cn×n be the set of n × n complex matrices and An the set of orthonormal n-tuples of vectors in Cn. For a vector c in Cn and a matrix A in Cn×n, the c-numerical range of A is the set Wc(A)={n∑i=1 Ci(Axi,xi):(x1,…xn)∈∧n} When c = (1,0,…,0), Wc(A) is reduced to the classical numerical range W(A) (see [1]). For the classical numerical range and its generalizations, one may see the survey article[2].     

On a Comparison Property of M—matrices

IntheresearchonthetheoryofM-matrices,wefrequentlyneedthefollowingtheoremasatool,whichiscalledthecomparisontheoremofanonsingularM-matrix(forexamplesee[5,Theorem2.2.5j).TheoremALetAbeanonsingularM-matrix,andletBbeaZ-matrixwithB2A.Then(1)BisanonsingularM-matrixI'(2)detB2detAj(3)A-'2B-'.obviously,theabovetheoremisnottrueforAtobeasingularM-matrix.InthispaperweshallextendTheoremAtOanyM-matrix,herethegeneralizedinverseisconsideredforgeneralizingassertion(3)ofTheoremA.AllnOtationanddefiniti…     

Sum Complexes—a New Family of Hypertrees

A k-dimensional hypertree X is a k-dimensional complex on n vertices with a full (k−1)-dimensional skeleton and \binomn-1k\binom{n-1}{k} facets such that H _k (X;ℚ)=0. Here we introduce the following family of simplicial complexes. Let n,k be integers with k+1 and n relatively prime, and let A be a (k+1)-element subset of the cyclic group ℤ _n . The sum complex X _A is the pure k-dimensional complex on the vertex set ℤ _n whose facets are σ⊂ℤ _n such that |σ|=k+1 and ∑ _x∈σ x∈A. It is shown that if n is prime, then the complex X _A is a k-hypertree for every choice of A. On the other hand, for n prime, X _A is k-collapsible iff A is an arithmetic progression in ℤ _n .     

Some Properties of a Class Self—homomorphism of BCI—algebras

ＢｙａＢＣＩ－ａｌｇｅｂｒａｗｅｍｅａｎａｎａｌｇｅｂｒａ（Ｘ；，０）ｏｆｔｙｐｅ（２，０）ｓａｔｉｓｆｙｉｎｇｔｈｅａｘｉｏｍｓ：（１）（（ｘｙ）（ｘｚ））（ｚｙ）＝０；（２）（ｘ（ｘｙ））ｙ＝０；（３）ｘｘ＝０；（４）ｘｙ＝ｙｘ＝０ｘ＝ｙｆｏｒａｎｙｘ，ｙａｎｄｚｉｎＸ．ＦｏｒａｎｙＢＣＩ－ａｌｇｅｂｒａＸ，ｔｈｅｒｅｌａｔｉｏｎ≤ｄｅｆｉｎｅｄｂｙｘ≤ｙｉｆａｎｄｏｎｌｙｉｆｘｙ＝０ｉｓａｐａｒｔｉａｌｏｒｄｅｒｏｎＸ［１］．ＩｎａｎｙＢＣＩ－ａｌｇｅｂｒａＸ，…     

Quasi—Einstein Hypersurfaces in a Hyperbolic Space

§1.　IntroductionLetRijbethecomponentsofRiccitensorofann-dimensionalRiemannianmanifoldM.IfRij=Agij Bξiξj,　(i,j=1,2,…,n)(1.1)whereξisanunitvectorfield,thenMiscalledaquasi-EinsteinmanifoldanddenotedbyQE(ξ).Ifξisanisotropicvectorfield,thenMiscalledageneralizedquasi-Einsteinmanifold.Intheequality(1.1),AandBarescalarfunctions.WeknowQE(ξ)manifoldisEinsteinwhenB≡0.Especially,if〈ξ,ξ〉=e=±1,thenQE(ξ)iscalledanormalquasi-Einsteinmani-fold.Itiseasytoknowfrom[1]and[2]:Rij=R-Tn-1…     

ω — fundamental solutions supported in a half space

For a weight function ω let ${\cal D}^{\prime}_{(\omega)}({\rm R}^{n})$ denote the space of ultradistibutions of Beurling type on ?ⁿ in the sense of Braun, Meise and Taylor [3]. In the present note the existence of certain (local) fundamental solutions $E\in{\cal D}^{\prime}_{(\omega)}({\rm R}^{n})$ for a partial differential operator P(D) with constant coefficients is characterized by an algebraic condition for the zeros of P and the weight function ω.