LATTICES OF STRUCTURE MODELS AND DATABASE SCHEMES

This paper deals with basic properties of lattices of structure models. The form of models considered here is used in at least three areas: reconstructabilily analysis, analysis of contingency tables, and relational and probabilistic database design. The fact that the set of all models is structured as a lattice has been part of the basic formulation of problems in reconstructabilily analysis, while in the other two areas this aspect, while not necessarily less important, has represented o less major line of development

Various class of the models are considered here. The paper characterizes and explores lattice properties of these classes of models, and develops means to make structural comparisons among them, including definition of a structural distance with which the lattice of models is a metric lattice. The paper includes a proof of the modularity of the lattices and of a formula for determining their height, as well as a number of algorithms for determining the structural distance

The paper gives a detailed consideralion of a strategy for partition search of the lattice of models and defines a recursive Boolean lattice as a data structure that extends the partition search strategy by recursive partioning.     

U-curve: A branch-and-bound optimization algorithm for U-shaped cost functions on Boolean lattices applied to the feature selection problem

This paper presents the formulation of a combinatorial optimization problem with the following characteristics: (i) the search space is the power set of a finite set structured as a Boolean lattice; (ii) the cost function forms a U-shaped curve when applied to any lattice chain. This formulation applies for feature selection in the context of pattern recognition. The known approaches for this problem are branch-and-bound algorithms and heuristics that explore partially the search space. Branch-and-bound algorithms are equivalent to the full search, while heuristics are not. This paper presents a branch-and-bound algorithm that differs from the others known by exploring the lattice structure and the U-shaped chain curves of the search space. The main contribution of this paper is the architecture of this algorithm that is based on the representation and exploration of the search space by new lattice properties proven here. Several experiments, with well known public data, indicate the superiority of the proposed method to the sequential floating forward selection (SFFS), which is a popular heuristic that gives good results in very short computational time. In all experiments, the proposed method got better or equal results in similar or even smaller computational time.     

XML关键字检索的访问控制规则和索引

XML数据库的关键字检索简单易用,并且用户不必了解数据库的模式,近期受到人们的广泛关注。当前的相关研究主要集中于关键字检索的算法以及返回结果的组织和排序,然而却忽视了关键字的安全访问控制问题。结合XML关键字搜索和XML安全访问控制,提出一种新的建立于XML Schema上基于角色的访问控制规则SRACP(Schema Role Access Control Policy),并在SRACP规则的基础上建立安全的XML关键字检索的索引(SRACP-Index),包括:SRACP-Index的数据结构,SRACP-Index的构建和算法,以及如何利用SRACP-Index的建立进行SSLCA的查询。最后通过实验证明该索引和SSLCA查询算法的有效性。     

黄页搜索引擎中二次检索的实现技术

搜索引擎的目的在于快速有效地找到用户需求的信息,在黄页搜索引擎中,通过关键字搜索,可以返回大量的信息,但其中的大部分信息不在用户需求的范围内.二次检索的定义是,在一次检索结果的基础上,按照特定的条件进行筛选,获得更为满足用户需求的结果.显然,二次检索在黄页搜索中的应用是必要的.基于这样的需求,提出了一种使用内存数据库和黄页搜索引擎联合进行二次搜索的方法.     

Searching for information in an online public access catalogue (OPAC): the impacts of information search expertise on the use of Boolean operators

Abstract Boolean systems still constitute most of the installed base of online public access catalogues (OPACs) in the French universities even if many studies have shown that Boolean operators are not frequently used by ‘non‐librarian’ users (by contrast with professional librarians). The first study examined the use of Boolean operators by French university students; In the second study, elaborated to evaluate the impact of information search expertise on this use, Boolean operators are explicitly presented and participants were explicitly invited to use them. We assumed that university students would not frequently use the operators in searching, and that even if they were explicitly invited to make use of them. Results obtained with the first study based on transaction logs analyses confirmed that French university students did not frequently use Boolean operators. The impact of information search expertise, analysed in the second study, compared three levels of expertise: Novice (university students), intermediate (future professional librarians), and expert (professional librarians). Results showed that, even if the three groups were invited to use Boolean operators, this use increased significantly with the level of information search expertise. University students, if they manage procedural functions of connectives in natural language, do not always manage the whole set of procedural functions carried by such connectives when used in the documentary language. So, the relevance of presenting explicit Boolean operators in the OPACs when users are ‘non‐librarians’ is questioned.     

启发式图搜索算法RA~*的改进算法IRA~*及IRA′

本文在文[1]基础上,对两种RA~*算法进行了比较研究,通过引入感兴趣集,给出了RA~*算法的改进算法IRA~*和IRA’,并且证明了IRA~*算法的可采纳性.从算法所扩展的结点数目这一角度来看,IRA~*算法明显优于RA~*算法.若感兴趣集并不包含最佳路径上的结点,则IRA~*算法的变形——IRA’算法可用来寻找一条较佳的求解路径.     

一种改进的参考文献搜索模型及相关性技术研究

基于Web的参考文献检索越来越受到欢迎，但是现有的参考文献相关性计算方法不能准确地给出参考文献的相关性，从而影响了用户文献检索的质量。首先给出了一个参考文献结构模型，在该模型中提出了虚节点的概念，从而大大拓展了文献检索的范围；其次在参考文献结构模型的基础上，通过充分挖掘参考文献之间的引用关系来计算参考文献在参考文献信息库中的重要性。通用组合位置／频率法与参考文献引用相关性技术的结合应用大大提高了文献检索的精度和质量。     

表达式的覆盖、分解与划分

本文把简单表达式（项和原子）视为语言Ｌ的Ｈｅｒｂｒａｎｄ域或Ｈｅｒｂｒａｎｄ基中的集合．作者提出覆盖表达式的概念,得到２个表达式之间覆盖关系的判别准则．对多个表达式,作者提出表达式的分解概念及相应的分解算法,在此基础上,本文给出卫个表达式覆盖多个表达式的等价条件．根据集合的划分公式,得到划分表达式的方法．最后定义１个变换把合取式转换为简单表达式,从而方便地把简单表达式的结果推广到合取式．本文是作者提出的一种标记逻辑程序的过程语义的理论基础．     

复杂条件下的社区搜索方法

社区搜索旨在寻找包含给定节点集的社区，能够快速获取个性化的社区信息.针对现有社区搜索算法难以满足复杂搜索条件的现状，提出条件社区搜索这一新问题.解决该问题有助于对社交网络进行智能分析，在复杂搜索条件下为用户提供更好的社区结果.首先，基于布尔表达式，给出条件社区搜索问题的形式化定义，可有效表达给定节点不能出现在社区内以及给定节点中至少有一个出现在社区内的要求.接着，提出解决条件社区搜索问题的通用框架，包括对搜索条件进行简化、根据简化后的搜索条件进行多次单项条件社区搜索、合并各单项条件社区搜索的结果等主要步骤.同时，提出"社区搜索+过滤"的方法和给点加权的方法来进行单项条件社区搜索.最后，真实数据集上的大量实验结果表明所提方法的正确性和有效性.     

概念格与粗糙集的关系研究

概念格理论和粗糙集理论是两种不同的知识表示与知识发现的工具,都已被成功应用于许多领域.粗糙集理论的数据表现方式是信息系统,其研究基础是对象之间的等价关系;概念格理论的数据表现方式是形式背景,其研究基础是一种有序的层次结构--概念格.本文讨论了概念格理论与粗糙集理论之间的基本联系;重点分析了形式概念与等价类之间、概念格与分划之间的关系;证明了概念格与分划之间可以相互转换,给出了转换算法,并用例子加以说明.     

Solution of Euclidean combinatorial optimization problems by the method of construction of a lexicographic equivalence

A method of space partition based on an equivalence relation is considered. Based on a lexicographic exhaustive search for equivalence classes, algorithms are developed for solution of a new class of optimization problems, namely, linear conditional Euclidean problems of lexicographic combinatorial optimization.Translated from Kibernetika i Sistemnyi Analiz, No. 5, pp. 155–125, September–October 2004.     

Tabu搜索在特征选择中的应用

研究利用Tabu搜索从大特征集中选择一组有效特征的问题.分析了Tabu搜索中表长、邻域大小和候选解数量等参数对Tabu搜索的影响.对两种特征选择的问题,与经典及最近新提出的一些特征选择方法如SFS,SBS,GSFS,GSBS,PTA,BB,GA和SFFS,SFBS等算法的实验比较表明,Tabu搜索在求解时间和解的质量上都取得了满意的结果.     

基于搜索空间划分的概念生成算法

概念格作为形式概念分析理论中的核心数据结构,在机器学习、数据挖掘和知识发现、信息检索等领域得到了广泛的应用.概念格的构造在其应用过程中是一个主要问题.提出了一种基于搜索空间划分的概念生成算法SSPCG(search space partition based concepts generation),它将属性集合的幂集看作初始闭包搜索空间,迭代地将每个搜索空间划分为一些子搜索空间,并引入了子搜索空间的有效性判断,只搜索那些能生成正规闭包的子搜索空间,有效地提高了搜索效率;同时,在计算闭包过程中保存一些必要的中间结果,用来提高闭包运算速度.由于所有子搜索空间是独立的,所以该算法可以很容易地扩展为并行算法.在随机生成的数据集和真实数据集上进行的实验测试表明,本算法的时间性能要优于Ganter提出的NextClosure算法.     

搜索问题的代数描述及其算法

文中给出了搜索问题的一种代数描述方法，在这种描述方法的基础上，给出了一个算法模式。以货郎担问题的动态规划－分支限界法为例，讨论了如何用所给出的算法模式来设计饱含多咱算法设计技术的算法，称这种算法为混合（ｈｙｂｒｉｄ）算法。还讨论了如何用面向对象的方法进行程序设计。这种求解问题的方法不仅为算法的自支生成提供了一种有力的工具，如果用面向对象的方法进行程序设计，还能提高代码的利用率。     

博弈树并行搜索算法

本文分析了博弈树并行搜索算法中的主变量分裂算法的同步开锁问题。     

基于Gnutella协议的P2P网络路由搜索算法:Light-Flooding

通过对Gnutella协议搜索算法的分析，结合Gossip分布式向前搜索算法和生成树算法的优点，实现了一种高效的路由搜索算法：Light—Flooding。实验结果表明：与Gossip算法相比，Light—Flooding算法提高搜索效率63．4％，减少冗余消息60％，平均延迟为2．6s，使网络的整体综合性能维持在一个优良状态。     

交叉算子的搜索能力

文中对遗传算法中常用的交叉算子的搜索能力进行了讨论,综合考虑了交叉算子对染色体的双重作用,给出了染色体在交叉算子作用下数量和分布范围的变化规律,得到了模式变化的极限性能,证明了交叉算子在演化代数增加的时候能够使模式内部各基因趋于独立,并且只要组成模式的各个基因都存在,则该模式一定能够被搜索到,此时模式的极限概率等于组成该模式各基因的初始概率（也就是基因的极限概率）的乘积,并且与模式的定义长度无关,说明了交叉算子使群体分布扩散的特性,从而可以进一步改善遗传算法的性能     

基于汉语拼音的模糊查询及其在图书馆管理系统中的应用

在图书馆管理系统的查询功能中,模糊查询可以使得整个系统的查询、管理变得更简洁和高效。通过区位码实现汉字拼音模糊查询,主要介绍其基本思想、算法实现示例以及使用的实例,来展示拼音模糊查询的实现方法,解决汉字模糊查询的弊端。     

GO-MOKU SOLVED BY NEW SEARCH TECHNIQUES

Many decades ago, Japanese professional Go-Moku players stated that Go-Moku (five-in-a-row on a horizontally placed 15×15 board) is a won game for the player to move first. So far, this claim has never been substantiated by (a tree of) variations or by a computer program. Meanwhile, many variants of Go-Moku with slightly different rules have been developed. This paper shows that for two common variants, the game-theoretical value has been established.
Moreover, the Go-Moku program Victoria is described. It uses two new search techniques: threat-space search and proof-number search. One of the results is that Victoria is bound to win against any (optimal) counterplay if it moves first. Furthermore, it achieves good results as a defender against nonoptimally playing opponents. In this contribution we focus on threat-space search and its advantages compared to conventional search algorithms.     

在动态开放环境中的一种跳步实时搜索算法

本文在分析动态开放环境特性的基础上，提出了适应这些特性的搜索算法所应具有的性质，给出了一种适应动态环境的搜索算法——跳步算法．通过初步实验，对算法性能进行了分析与说明，表明算法具有较好的运行效率.