A note on the Undirected Rural Postman Problem polytope

This note refers to the article by G. Ghiani and G. Laporte ``A branch-and-cut algorithm for the Undirected Rural Postman Problem', Math. Program. 87 (2000). We show that some conditions for the facet-defining property of the basic non-trivial inequalities are not sufficient and that the Rural Postman Problem polytope is more complex even when focusing on canonical inequalities only.     

A branch-and-cut algorithm for the Undirected Rural Postman Problem

The well-known Undirected Rural Postman Problem is considered and a binary linear problem using new dominance relations is presented. Polyhedral properties are investigated and a branch-and-cut algorithm is developed. Extensive computational results indicate that the algorithm is capable of solving much larger instances than previously reported. Received: December 1, 1997 / Accepted: October 13, 1999?Published online January 27, 2000     

A two-stage solution approach for the Directed Rural Postman Problem with Turn Penalties

In this paper, we consider the Directed Rural Postman Problem with Turn Penalties (DRPP-TP). A solution is a tour that traverses all required arcs of the graph. The total cost of the tour is the sum of the lengths of the traversed arcs plus the penalties associated with the turns. One solution approach involves transforming the arc routing problem into an equivalent node routing problem. An alternative direct approach (without graph transformation) that involves two stages has been proposed in the literature. In the first part of this paper, we investigate the applicability of the direct approach. We identify several characteristics of the input instance that make this approach effective and present several limitations of this approach. In the second part of this paper, we describe an integer linear program that is combined with a local search algorithm. This combination produces high-quality solutions to the DRPP-TP in a reasonable amount of computing time.     

现代物流技术中装卸工问题的拟多项式时间可解情况

装卸工问题是从现代物流技术中提出的一个实际问题，这个问题的雏形早在上个世纪60年代中国科学院数学研究所就提出和研究过。现代物流业的迅速发展，促成和推动装卸工问题的提出和研究。装卸工问题是一个新的NP困难的组合优化问题，本文研究限制情形下的装卸工问题，并证明是拟多项式时间可解的。     

中国邮路问题的一个解法

本给出中国邮路问题的一个解法。虽然它仍只是初始方案，但因考虑了问题的足够信息，因而这种方案至少拉近了与最优解的距离。     

A solvble case of the Capacitated Chinese Postman Problem

<正> The Capacitated Chinese Postman Problem(CCPP)is NP—hard.However,there aresome solvable cases.In this paper we show that a CCPP is solvable provided all arcs'de-mands are larger than one third of the vehicle's capacity.     

A Routing and Scheduling Problem for a Rail System: A Case Study

Railways are extensively used in the Australian sugar industry to transport cane from farms to the factories. Development of efficient schedules manually is difficult, given a weak set of constraints and the need to consider operating and capital costs and the deterioration of cane in the period between harvesting and processing. The Cane Railway Scheduling Problem deals with the design of a regular schedule. The algorithm devised is based on a serial decomposition (with routing and scheduling considered separately) to generate a trial solution, modification of the trial solution to provide a first feasible solution and iterative refinement to provide the final solution. Comparison of solutions produced by the algorithm and those generated manually suggests potential savings ranging from 20% to 30% in annual operating costs with accompanying reductions in rolling stock requirements. Use of the model in the industry is noted.     

评“二阶线性微分方程可解的条件”一文

指出该文定理不是新的,例子中的解法也很繁杂,介绍了作者所得到的关于Riccati方程和二阶线性微分方程的一些新的可积类型.     

一类奇异四阶方程组边值问题的多重正解

该文应用不动点指数理论,研究了一类奇异非线性四阶微分方程组的两点边值问题,通过相应线性问题的第一特征值建立了其正解的存在性与多解性定 理,在本质上改进和推广了［1］的结论.     

一类四阶奇异边值问题的多重正解

应用锥上的不动点指数理论，研究了一类奇异非线性四阶微分方程组的两点边值问题，通过相应线性问题的第一特征值建立了其正解的存在性与多解性定理．     

一阶系统非线性边值问题的奇摄动*

本文应用比较定理研究了一类非线性边界条件的向量非线性奇摄动问题εx='f(t,x,y,e)εy'=g(t,x,y,ε)x(0)=A(ξ₁,ξ₂,x(1)-x(0),y(1)-y(0),ε)y(0)=B(ξ₁,ξ,x(1)-x(0),y(1)-y(0),ε)这里ξ₁,ξ₂为ε的函数。0<ε<<1,在适当的条件下,作出了任意次精度的渐近展式。并得出余项估计。     

一类次线性非自治二阶系统的多重周期解

利用广义鞍点定理研究非自治二阶系统周期解的存在性.在具有部分周期位势和次线性增长非线性项时,给出了多重周期解存在的充分条件,所得结论推广了已知结果.     

半直线上含导数项的二阶微分方程组边值问题的正解

应用Sadovskii不动点定理不动点理论讨论半直线上含导数项的二阶微分方程组,得到了在边值条件为非负常数时的正解的存在性定理     

Application of the Residual Method in the Right Hand Side Reconstruction Problem for a System of Fractional Order

Computational Mathematics and Mathematical Physics - For a system of nonlinear fractional differential equations, the problem of reconstruction of an unknown input action is considered. An...     

The Essential Spectrum of a System of Singular Ordinary Differential Operators of Mixed Order. Part I: The General Problem and an Almost Regular Case

The paper develops the notion of signed contents and measures on the basis of a new definition. It form a common roof for some well-known partial notions which appeared to be incompatible. The paper also redefines the notion of angular pairs of contents and measures, to the effect that the two notions are connected via an attended Jordan decomposition theorem. The decisive idea is a new difference formation for contents and measures.