Improved Approximation for Breakpoint Graph Decomposition and Sorting by Reversals

Sorting by Reversals (SBR) is one of the most widely studied models of genome rearrangements in computational molecular biology. At present, is the best known approximation ratio achievable in polynomial time for SBR. A very closely related problem, called Breakpoint Graph Decomposition (BGD), calls for a largest collection of edge disjoint cycles in a suitably-defined graph. It has been shown that for almost all instances SBR is equivalent to BGD, in the sense that any solution of the latter corresponds to a solution of the former having the same value. In this paper, we show how to improve the approximation ratio achievable in polynomial time for BGD, from the previously known to for any > 0. Combined with the results in (Caprara, Journal of Combinatorial Optimization, vol. 3, pp. 149–182, 1999b), this yields the same approximation guarantee for n! – O((n – 5)!) out of the n! instances of SBR on permutations with n elements. Our result uses the best known approximation algorithms for Stable Set on graphs with maximum degree 4 as well as for Set Packing where the maximum size of a set is 6. Any improvement in the ratio achieved by these approximation algorithms will yield an automatic improvement of our result.     

On Inverse Problems of Optimum Perfect Matching

As far as we know, for most polynomially solvable network optimization problems, their inverse problems under l ₁ or l norm have been studied, except the inverse maximum-weight matching problem in non-bipartite networks. In this paper we discuss the inverse problem of maximum-weight perfect matching in a non-bipartite network under l ₁ and l norms. It has been proved that the inverse maximum-weight perfect matching under l norm can be formulated as a maximum-mean alternating cycle problem of an undirected network, and can be solved in polynomial time by a binary search algorithm and in strongly polynomial time by an ascending algorithm, and under l ₁ norm it can be solved by the ellipsoid method. Therefore, inverse problems of maximum-weight perfect matching under l ₁ and l norms are solvable in polynomial time.     

企业理财系统相关性研究

企业理财系统相关性由企业理财内容循环的相关性、企业理财过程循环的相关性、企业理财内容循环与过程循环的相关性构成.研究企业理财系统相关性,对探索企业理财系统及规律性、增强企业理财系统柔性及提高企业经济效益都有着重要的实际指导意义和理论价值.     

A study on cyclic bandwidth sum

Suppose G is a graph of p vertices. A proper labeling f of G is a one-to-one mapping f:V(G)→{1,2,…,p}. The cyclic bandwidth sum of G with respect to f is defined by CBS _f (G)=∑ _uv∈E(G)|f(v)−f(u)| _p , where |x| _p =min {|x|,p−|x|}. The cyclic bandwidth sum of G is defined by CBS(G)=min {CBS _f (G): f is a proper labeling of G}. The bandwidth sum of G with respect to f is defined by BS _f (G)=∑ _uv∈E(G)|f(v)−f(u)|. The bandwidth sum of G is defined by BS(G)=min {BS _f (G): f is a proper labeling of G}. In this paper, we give a necessary and sufficient condition for BS(G)=CBS(G), and use this to show that BS(T)=CBS(T) when T is a tree. We also find cyclic bandwidth sums of complete bipartite graphs. Dedicated to Professor Frank K. Hwang on the occasion of his 65th birthday. Supported in part by the National Science Council under grants NSC91-2115-M-156-001.     

休闲消费中的流体验生命周期探究

体验是随着消费者休闲消费的经验不断丰富而不断变化的，是一个动态的过程。体验如何变化以及休闲消费企业针对体验的动态过程的对策是需要解决的一个问题。利用流理论，从心理学角度探究休闲消费中的消费者体验主要有以下几点：首先，对心理学视角下的三个代表体验理论进行述评；其次，基于流体验理论提出休闲消费的流体验生命周期以及体验的总效用模型；最后，基于流体验生命周期从个人和休闲两个层面，提出提高消费者休闲消费倾向的对策。     

平稳，增长，何者更重要？

 依据Lucas（1987）的理论模型，本文探讨了改革前后中国经济波动与经济增长的福利成本，结果发现：改革前的经济波动不是很重要；但从改革后或整个样本区间看，在合意的参数情况下，中国经济额外增长1%的福利收益要小于消除经济波动的福利成本。这意味着宏观经济波动对中国有着重要意义，中国政府应在保持经济增长的同时，更应关注保持经济的平稳性。     

新科技革命对国际政治格局的影响

本世纪50年代兴起的新科技革命对整个世界格局发生了重大影响。文章阐述了新科技革命导致各国实力的不平衡，引起国际政治行为主体地位和角色发生变化，从而促使国际政治格局发生演变；新科技革命加快了国际政治格局的变革周期；并改变了国际政治格局转化的手段。     

A Note on Exponentially Smoothed Seasonal Differences

Filtering economic time series can be justified if variations within a certain frequency interval are relevant for the problem at hand. It is shown here that exponential smoothing of seasonal differences provides a simple means of damping short oscillations, including seasonal ones.     

发展农业循环经济的机制创新

农村生态环境问题严重危害了农业生态系统和农业可持续发展。发展农业循环经济能够防治农村环境污染,合理利用农业资源,增加农民收入和农业产出,实现农业可持续发展。发展农业循环经济应大力发展生态农业,循环利用农业资源,发展农村循环工业,推进城乡一体化循环,实施农业绿色技术创新,增强发展农业循环经济意识等。     

弗莱“循环论”文学思想的理论特质及其价值

诺思洛普.弗莱是英语国家最杰出的文学批评家,他的理论著作《批评的剖析》被誉为二十世纪西方文学批评理论的《圣经》。弗莱的文学循环论将文学的发展视为一个以神话——原型为基础的循环运动过程,对整个二十世纪后半叶文学批评从语言研究转向文化研究有着深远的影响。