On Block Ordering of Variables in Graphical Modelling

Abstract.  In graphical modelling, the existence of substantive background knowledge on block ordering of variables is used to perform structural learning within the family of chain graphs (CGs) in which every block corresponds to an undirected graph and edges joining vertices in different blocks are directed in accordance with the ordering. We show that this practice may lead to an inappropriate restriction of the search space and introduce the concept of labelled block ordering B corresponding to a family of B - consistent CGs in which every block may be either an undirected graph or a directed acyclic graph or, more generally, a CG. In this way we provide a flexible tool for specifying subsets of chain graphs, and we observe that the most relevant subsets of CGs considered in the literature are families of B -consistent CGs for the appropriate choice of B . Structural learning within a family of B -consistent CGs requires to deal with Markov equivalence. We provide a graphical characterization of equivalence classes of B -consistent CGs, namely the B - essential graphs , as well as a procedure to construct the B -essential graph for any given equivalence class of B -consistent chain graphs. Both largest CGs and essential graphs turn out to be special cases of B -essential graphs.     

汇编程序覆盖测试中分支路径数的计算

说明了覆盖测试是软件测试中的重要方法,是软件动态测试的基本手段。并提出通过基本块存储矩阵和邻接表来处理汇编语言程序流图,从而计算其分支路径数的算法并验证其正确性,为进一步的分支覆盖率计算奠定基础。实验证明,该方法能高效准确地计算出给定汇编程序的分支路径数。     

带延迟的分组密码算法密钥结合模式设计

提出了一种分组密码算法的延迟结合模式,进行了基于信息论原则的安全性证明,并对加入延迟后的密钥执行效率进行了评估。对于算法公开的分组密码,使用密钥延迟技术加强密码体制本身的强度,弱化种子密钥通过互联网公开分发造成的信息泄漏,特别可以有效阻止中间人唯密文进行的算法还原攻击。     

块H-矩阵的刻画

【摘要】根据块对角占优、块严格对角占优和不可约对角占优矩阵的概念,针对a连对角占优矩阵,应用分块技术,给出和引进了块弱不可约a严格对角占优矩阵的概念,并在此基础上给出了简捷的块H-矩阵的充要条件和充分条件的刻画,推广和包含了已有的相应结果。     

大盘,中国城市成长的必由之路

通过对中西方城市成长过程的探讨和对比,总结出中西方城市发展的一般规律。结合中国国情,探讨中国城市发展的独特规律,得出大盘是中国城市成长的必由之路的研究结论,同时指出目前中国大盘所存在的问题和解决对策。该结论对政府进行城市规划和开发商进行大盘开发建设具有重要的参考意义。     

General scores statistics on ranks in the analysis of unbalanced designs

The authors consider the situation of incomplete rankings in which n judges independently rank k_i ∈ {2, …, t} objects. They wish to test the null hypothesis that each judge picks the ranking at random from the space of k_i! permutations of the integers 1, …, k_i. The statistic considered is a generalization of the Friedman test in which the ranks assigned by each judge are replaced by real‐valued functions a(j, k_i), 1 ≤ j ≤ k_i ≤ t of the ranks. The authors define a measure of pairwise similarity between complete rankings based on such functions, and use averages of such similarities to construct measures of the level of concordance of the judges' rankings. In the complete ranking case, the resulting statistics coincide with those defined by Hájek & ?idák (1967, p. 118), and Sen (1968). These measures of similarity are extended to the situation of incomplete rankings. A statistic is derived in this more general situation and its properties are investigated.     

一种适用于智能家电嵌入式软件的框架构件模型

通过对家电控制器常用MCU体系结构、程序设计语言、常用家电控制程序设计代码以及外设驱动源码的研究,制定了一种应用于智能家电嵌入式软件的框架构件规范,实现了划分和设计框架代码片段,以及对框架代码片段封装的方法;所设计的模型已成功应用于某863项目中。     

Causes and Consequences of Block Share Purchases. Evidence from Spanish Non-Financial Firms

The structure of Spanish capital markets doesnot facilitate an efficient market forcorporate control through takeover process,which assumes that inefficient management isreplaced by competing teams. The ownershipstructure of listed companies is highlyconcentrated, with extremely low floating stockfor some companies. At the same time animportant number of companies have introducedanti-takeover provisions in their statutes.There is another way of disciplining managementthrough the exit solution: by transferring theownership of significant blocks of shares, amarket for partial corporate control, asalternative to the takeover market. Theobjective of this paper is to test empiricallythe causes and consequences of block purchasesin Spain for non-financial listed companies.The main results are: i) There is no evidencethat previous poor performance of the companiescauses block increases; ii) Block increasesoccur more frequently in companies with lowerownership concentration. After the blockincrease, on average, the ownership of thelargest shareholder increases. iii) After blockincreases there are significant board changes,for both executive board members and also fornon-executives. (iv) The transfer of blocksoccurs more frequently for smaller companies.We conclude that agency theory predictionsabout the disciplining role of partial takeoveractivity are not fully supported. They arecontingent on institutional characteristics ofthe corporate governance system.     

略论宋代类书大盛的原因

类似于百科全书式的古类书,对史学研究和古籍整理具有十分重要的功用.它起源于曹魏时期,入唐以后,类书编修逐渐增多,至宋代遂大盛,甚至明清两代也难望其项背.宋代类书所以很多,有三个重要原因:一是宋代帝王重视文治,个人也比较好学,所以大力鼓励类书的编修;二是科举制度到宋代通过一系列的改革,应试人数大大增多,考试内容发生变化,对类书的需要量随之增大;三是宋代的雕版印刷技术已经完善,装订形式也有进步,为类书的刊行奠定了良好的技术基础.     

城市更新中历史街区的功能置换

历史街区具有时代特征和历史价值,但历史街区在城市更新中面临诸多的问题和矛盾。为保护街区的历史文化,提出利用功能置换的方式改造历史街区,并分析这种改造方式的意义与效益。通过实例佐证历史街区的功能置换在城市更新中的经济性、合理性与前瞻性。