Constraint Solving for Term Orderings Compatible with Abelian Semigroups, Monoids and Groups

It is crucial for the performance of ordered resolution or paramodulation-based deduction systems that they incorporate specialized techniques to work efficiently with standard algebraic theories E. Essential ingredients for this purpose are term orderings that are E-compatible, for the given E, and algorithms deciding constraint satisfiability for such orderings.Here we introduce a uniform technique providing the first such algorithms for some orderings for abelian semigroups, abelian monoids and abelian groups, which we believe will lead to reasonably efficient techniques for practice.Our algorithms are in NP, and hence optimal, since in addition we show that, for any well-founded E-compatible ordering for these E, the constraint satisfiability problem is NP-hard even for conjunctions of inequations.     

Paramodulation and Knuth–Bendix Completion with Nontotal and Nonmonotonic Orderings

Up to now, all existing completeness results for ordered paramodulation and Knuth–Bendix completion have required term ordering to be well founded, monotonic, and total(izable) on ground terms. For several applications, these requirements are too strong, and hence weakening them has been a well-known research challenge.Here we introduce a new completeness proof technique for ordered paramodulation where the only properties required on are well-foundedness and the subterm property. The technique is a relatively simple and elegant application of some fundamental results on the termination and confluence of ground term rewrite systems (TRS).By a careful further analysis of our technique, we obtain the first Knuth–Bendix completion procedure that finds a convergent TRS for a given set of equations E and a (possibly non-totalizable) reduction ordering whenever it exists. Note that being a reduction ordering is the minimal possible requirement on , since a TRS terminates if, and only if, it is contained in a reduction ordering.     

Experiments with discrimination-tree indexing and path indexing for term retrieval

This article addresses the problem of indexing and retrieving first-order predicate calculus terms in the context of automated deduction programs. The four retrieval operations of concern are to find variants, generalizations, instances, and terms that unify with a given term. Discrimination-tree indexing is reviewed, and several variations are presented. The path-indexing method is also reviewed. Experiments were conducted on large sets of terms to determine how the properties of the terms affect the performance of the two indexing methods. Results of the experiments are presented.This was supported by the Applied Mathematical Sciences subprogram of the Office of Energy Research, U.S. Department of Energy, under Contract W-31-109-Eng-38.     

基于色彩主特征的快速图像检索

提出了一种新颖而又简单直观的图像索引机制。这种方法通过统计图像数据库的低层像素特征,用中值切割法构建索引树,把自然景物图像数据库分成易于描述的不同视觉主题,并籍此来进行高效的图像检索。索引树的构建有别于传统的完全基于数值本身的聚类方法,因而聚类结果视觉含义更明显。本文以颜色主题为例实现了此方法,并通过实验论证了方法的高效和快速。图像索引码以二进制形式给出,因而所需存储空间也极小。     

Indexing Web Sites

ABSTRACT

Back-of-book style Web site indexing enhances access to specific information in Web sites. To index a Web site requires the skills of traditional print indexing, plus more. This article discusses the importance of indexes on the Web, and specifically examines the indexing of the Australian Society of Indexers' Web site using the Web site indexing program HTML Indexer. Topics include working with Webmasters, software for Web indexing, how to choose indexable matter and depth of indexing, the idea of links as page number substitutes, the use of subdivisions, index style and display, and planning for updating the index.     

一种适用于汉语的索引文件结构

本文给出一种以词语为索引项的索引文件存储结构,以及基于这种结构的索引查询算法.首先分析中文索引库的分布规律,接着在此基础上设计了一种逆序存储的三层索引结构,这种结构在创建索引时能根据词语频率自动调整存储顺序,最后给出一种基于自动机和逆向最大匹配的索引查询算法.实验系统TIFS将三层索引结构与B树、哈希方法在时间和空间复杂度方面进行对比,结果表明,对于大规模的中文文本检索,三层索引结构的综合效果最好.     

一种结合术语部件库的术语提取方法

术语是知识体系的核心成员,术语提取技术是大规模本体工程自动或半自动构建、扩充的关键技术之一。文章首先介绍了现有的一些术语提取技术,并在此基础上探讨了一种结合术语部件库的术语提取方法,并对这种方法的优点和未来的工作进行了分析。     

基于XML的信息检索技术

传统的信息检索方法无法为用户准确地提供所需的资料,这主要是由于传统的HTML网页结构上的缺陷造成的。文中通过比较HTML文档和XML文档在结构和语义上的差异,阐述了XML文档在信息检索技术中的优势和XML文档必将成为新一代网页模式的趋势。目前已经有很多权威编程工具和数据库支持从XML文档中抽取信息,越来越多的软件提供XML接口,文中以Microsoft公司的.NETFramework为例,介绍了如何从XML文档中检索信息。试验证明基于XML的信息检索技术较好地解决了Internet上资料获取的困难。     

基于内容的遥感图像数据库的多维索引技术

如何高效地存储和管理海量的遥感图像数据,使其更好地满足多用户访问和数据查询等需求,是当前研究的一个热点问题;索引是快速访问大型数据库的前提,构建索引在遥感图像数据库的管理中有着举足轻重的作用;鉴于此,该文提出了一种基于内容的遥感图像数据库的多维索引技术,笔者详细论述该索引方法的动机、原理和实现过程,最后将此索引方法应用于一个大型的遥感图像数据库中,实验0数据验证了该方法的有效性.     

基于聚类的图像视觉内容检索和索引

图像是一种典型的可以大量获取的多媒体数据,对它们进行内容管理具有实际意义,描述在BOIC系统中提出并实现的基于聚类机制的图像视觉内容检索和索引方法．首先给出以视觉特征、空间结构、语义注释等来表示图像内容的模型;然后给出基于该模型的三个检索算法,包括基于视觉感知的颜色检索算法、轮廓检索算法、主色调扩展检索算法;最后给出采用集簇算法时媒体数据进行聚类的索引机制．它建立聚类索引表来缩小查询范围,从而提高了检索效率。     

PLC控制步进电机分度的设计与实现

简要介绍利用PLC控制步进电机对执行元件进行自动分度,重点介绍一种PLC控制步进电机的分度算法,可实现360°内转角误差为0,保证了精确分度,并给出分度算法梯形图.     

空间索引技术-回顾与展望

空间数据库系统通过引入空间索引机制来提高空间数据操作的效率。迄今人们已经提出了许多空间索引方法,文章回顾了这些方法的基本思想,并根据它们所采用的基础数据结构和存储空间数据的方法将现有的空间索引方法进行分类。最后,简要的讨论了空间索引方法的发展方向。     

Conditional Term Graph Rewriting with Indirect Sharing

For reasons of efficiency, term rewriting is usually implemented by term graph rewriting. In term rewriting, expressions are represented as terms, whereas in term graph rewriting these are represented as directed graphs. Unlike terms, graphs allow a sharing of common subexpressions. In previous work, we have shown that conditional term graph rewriting is a sound and complete implementation for a certain class of CTRSs with strict equality, provided that a minimal structure sharing scheme is used. In this paper, we will show that this is also true for two different extensions of normal CTRSs. In contrast to the previous work, however, a non-minimal structure sharing scheme can be used. That is, the amount of sharing is increased.     

From Chemical Rules to Term Rewriting

In this paper, rule-based programming is explored in the field of automated generation of chemical reaction mechanisms. We explore a class of graphs and a graph rewriting relation where vertices are preserved and only edges are changed. We show how to represent cyclic labeled graphs by decorated labeled trees or forests, then how to transform trees into terms. A graph rewriting relation is defined, then simulated by a tree rewriting relation, which can be in turn simulated by a rewriting relation on equivalence classes of terms. As a consequence, this kind of graph rewriting can be implemented using term rewriting. This study is motivated by the design of the GasEl system for the generation of kinetics reactions mechanisms. In GasEl, chemical reactions correspond to graph rewrite rules and are implemented by conditional rewriting rules in ELAN. The control of their application is done through the ELAN strategy language.     

Subgoal Strategies for Solving Board Puzzles

We show that a few simple search strategies can solve a variety of difficult puzzles ranging from the 15-puzzle to central solitaire, Rubiks cube, and several of its variants. One of these strategies automatically generates subgoals; another finds efficient sets of rules for the subgoals. The subgoals are based on the reversal of simple logical implications. With these strategies and a simple learning algorithm, we not only solve particular instances of these problems but automatically generate programs that solve all instances of the problem with reasonable efficiency. Our automatically generated program for Rubiks cube can solve a fully scrambled cube in about two minutes on a 66 Mhz 486 PC.     

Indexing and Retrieval of Audio: A Survey

With more and more audio being captured and stored, there is a growing need for automatic audio indexing and retrieval techniques that can retrieve relevant audio pieces quickly on demand. This paper provides a comprehensive survey of audio indexing and retrieval techniques. We first describe main audio characteristics and features and discuss techniques for classifying audio into speech and music based on these features. Indexing and retrieval of speech and music is then described separately. Finally, significance of audio in multimedia indexing and retrieval is discussed.     

复合布尔函数中含某单乘积项的快速判定算法

引入了布尔函数的基本积、单乘积项等概念,通过实例剖析了复合布尔函数中是否含某一单乘积项的一般判定方法,在该基础上提出了一种快速判定途径,并给出了快速判定算法的具体描述,同时对算法进行了实验,结果表明该算法快速有效。     

基于anchor模型的说话人检索技术

本文研究了基于anchor模型的说话人检索技术,提出了基于SCV分量方差和基于广义似然比聚类的模型剪枝方法,对基于序数比较的相似测度进行了改进,使SCV各分量的数值和比值都参与到识别中来,提高了检索性能.通过实验印证了将传统的说话人检索中的模型训练过程转变为计算语音相对于anchor说话人模型距离的映射过程,所带来的计算量和存储量的优势,为说话人检索在大型语音库和嵌入式系统的应用提出了新的思路.     

A New Term Significance Weighting Approach

The authors present a new term significance measure that integrates term frequency retrieval characteristics, term frequency, document collection characteristics, and both the term depth and width distribution characteristics. A new concept, the term depth distribution, is introduced and its impact on the term significance is analyzed. The authors address the features of the new term significance measure from the angles of the impact of the variables (parameters) on it and the iso-significance contour analyses. An experimental study was conducted to compare the newly developed approach with two other popular approaches from the perspectives of both efficiency and effectiveness. The results show that the newly developed approach achieves satisfactory performance. Issues for further research on this topic are suggested.