A Polynomial Time Approximation Scheme for the Problem of Interconnecting Highways

The objective of the Interconnecting Highways problem is to construct roads of minimum total length to interconnect n given highways under the constraint that the roads can intersect each highway only at one point in a designated interval which is a line segment. We present a polynomial time approximation scheme for this problem by applying Arora's framework (Arora, 1998; also available from http:www.cs.princeton.edu/~arora). For every fixed c > 1 and given any n line segments in the plane, a randomized version of the scheme finds a -approximation to the optimal cost in O(n ^O(c)log(n) time.     

数控车床编程CAI课件设计

应用计算机辅助教学是当前教学改革的重要内容,本文介绍了数控车床编程CAI课件的设计要点、设计方法和课件的主要功能及特点.     

敦煌疑伪经三种残卷缀合研究

敦煌文献中保存的一百多种疑伪经,绝大多数都不载于清以前的藏经,具有极高的研究价值。但其中不少都是残卷（片）,给整理研究工作带来了严重影响。《斋法清净经》《法王经》《十王经》是隋唐五代宋初时较为流行的三种疑伪经,通过考察这三部疑伪经在敦煌文献中的现存面貌,厘清其所存卷号以及完整或残缺的情况,并从内容接续、残字拼合、行款相同、字迹书风相近等角度进行比较分析,可将这三经中的32号残卷（片）缀合为10组。通过缀合,这些原本分裂的残卷得以重聚一处;借助缀接后的写本所显示的较为完整的信息,不仅可以为这些残卷（片）进行准确的定名,还可以对其形制、内容与性质做出更为客观、可靠的判断。     

The Travelling Salesman Problem on Permuted Monge Matrices

We consider traveling salesman problems (TSPs) with a permuted Monge matrix as cost matrix where the associated patching graph has a specially simple structure: a multistar, a multitree or a planar graph. In the case of multistars, we give a complete, concise and simplified presentation of Gaikov's theory. These results are then used for designing an O(m3 + mn) algorithm in the case of multitrees, where n is the number of cities and m is the number of subtours in an optimal assignment. Moreover we show that for planar patching graphs, the problem of finding an optimal subtour patching remains NP-complete.