Weighted Logics for Unranked Tree Automata

We define a weighted monadic second order logic for unranked trees and the concept of weighted unranked tree automata, and we investigate the expressive power of these two concepts. We show that weighted tree automata and a syntactically restricted weighted MSO-logic have the same expressive power in case the semiring is commutative or in case we deal only with ranked trees, but, surprisingly, not in general. This demonstrates a crucial difference between the theories of ranked trees and unranked trees in the weighted case.     

英语模糊限制语及其使用

就语言模糊理论研究的基本内容,探究模糊语言的语用功能,进一步揭示模糊限制语的分类及其在教学与交际中的使用,通过理论与实践相结合,逐步发挥模糊语言学对外语教学与研究的指导作用。     

Hedges and successors in basic algebras

The concept of hedge was introduced by Zadeh in the sake to amplify true values of linguistic terms. It was used by Bělohlávek and Vychodil for formal concept analysis of unsharp reasoning. The concept of successor was introduced by Caicedo and Cignoli for study of intuitionistic connectives and used by San Martín, Castiglioni, Menni and Sagastume in Heyting algebras. Since basic algebras form an algebraic tool for simultaneous treaty of many-valued logics and logics of quantum mechanics, it arises a natural question of generalization of these concepts also for basic algebras. This motivated our investigations on hedges and successors.     

安全辞典

脚本语言 是介于HTML和Java、C 、Visual Basic之类的编程语言之间的语言。HTML通常用于格式化文本和链接网页;编程语言通常用于向计算机发送一系列复杂指令。脚本语言也可用来向计算机发送指令,但它们的语法和规则没有可编译的编程语言那样严格和复杂,脚本语言主要用于格式化文本和使用以编程语言编写的已编译好的组件。     

Invariants, Patterns and Weights for Ordering Terms

We prove that any simplification order over arbitrary terms is an extension of an order by weight, by considering a related monadic term algebra called the spine. We show that any total ground-stable simplification order on the spine lifts to an order on the full term algebra. Conversely, under certain restrictions, a simplification ordering on the term algebra defines a weight function on the spine, which in turn can be lifted to a weight order on the original ground terms which contains the original order. We investigate the Knuth–Bendix and polynomial orders in this light. We provide a general framework for ordering terms by counting embedded patterns, which gives rise to many new orderings. We examine the recursive path order in this context.     

安全辞典

HTTP HTTP(Hyper Text Transport Protocol),超文本传输协议、用于支持WWW浏览的网络协议,是一种最基本的客户机/服务器的访问协议。它的主要作用就是对某个资源服务器的文件进行访问,包括对该服务器上指定文件的浏览、下载、运行等,也就是说通过HTTP我们可以访问Internet上WWW的资源。HTTP协议从1990年开始出现,发展到当前的HTTP 1.1标准,已经有了相当多的扩展,然而其最基本的实现非常简单。     

一种适用于复合术语的本体概念学习方法

术语的提取显然在本体概念学习中起着重要作用,由于汉语文本中词与词之间没有明显的界限,使得领域术语特别是复合术语的提取尤为困难。针对传统提取方法缺乏语义支持、计算量大、准确率低等不足,提出了一种适用于复合术语提取的本体概念学习方法。首先利用自然语言处理技术过滤掉与术语无关的成分,对语句进行自然切割,为领域术语提取提供完整的候选数据集,以保证候选领域复合术语不被误分。在此基础上,根据术语的领域统计和分布特征,利用术语频率和信息熵进行多策略的领域术语筛选,经同义术语识别与合并,获得领域概念集。经实验验证,提出的方法能够以较高的准确率从领域文本中提取出领域单词术语和复合术语。     

基于领域类别信息C-value的多词串自动抽取

该本的多词串抽取是自然语言处理领域一项重要的研究内容。该文提出了一种多类别C-value(Multi-Class C-value)方法,利用多词串在不同领域的分布信息改善领域相关的多词串抽取的性能。在汽车、科技和旅行三个领域的数据上进行实验,评价多词串的准确率,在top-100级别上,较传统的C-value方法在三个领域中分别提高了12、12和13个百分点。实验结果验证了方法的有效性。     

Simultaneous Approximation Terms for Multi-dimensional Summation-by-Parts Operators

This paper is concerned with the accurate, conservative, and stable imposition of boundary conditions and inter-element coupling for multi-dimensional summation-by-parts (SBP) finite-difference operators. More precisely, the focus is on diagonal-norm SBP operators that are not based on tensor products and are applicable to unstructured grids composed of arbitrary elements. We show how penalty terms—simultaneous approximation terms (SATs)—can be adapted to discretizations based on multi-dimensional SBP operators to enforce boundary and interface conditions. A general SAT framework is presented that leads to conservative and stable discretizations of the variable-coefficient advection equation. This framework includes the case where there are no nodes on the boundary of the SBP element at which to apply penalties directly. This is an important generalization, because elements analogous to Legendre–Gauss collocation, i.e. without boundary nodes, typically have higher accuracy for the same number of degrees of freedom. Symmetric and upwind examples of the general SAT framework are created using a decomposition of the symmetric part of an SBP operator; these particular SATs enable the pointwise imposition of boundary and inter-element conditions. We illustrate the proposed SATs using triangular-element SBP operators with and without nodes that lie on the boundary. The accuracy, conservation, and stability properties of the resulting SBP–SAT discretizations are verified using linear advection problems with spatially varying divergence-free velocity fields.     

汉语术语定义的结构分析和提取

本文介绍的工作是在汉语句法分析研究基础上的一种应用研究,对术语如何下定义问题进行了理论上的探讨。术语的定义形式在汉语语法结构方面提供了模板结构和构成方式,可以作为知识发现研究的数据基础,也可以作为特定领域的语法知识系统。本文针对电子学和计算机领域的语料进行了分词和词性标注处理,然后应用句法分析工具分析出句子中的短语成分,并根据汉语句子的句型结构,总结出术语定义的结构特点,自动提取定义的模板。最后根据已建立的数据和概念描述,给出了术语发现的算法。     

Simple Easy Terms

We illustrate the use of intersection types as a semantic tool for proving easiness result on λ-terms. We single out the notion of simple easiness for λ-terms as a useful semantic property for building filter models with special purpose features. Relying on the notion of easy intersection type theory, given λ-terms M and E, with E simple easy, we successfully build a filter model which equates interpretation of M and E, hence proving that simple easiness implies easiness. We finally prove that a class of λ-terms generated by ω₂ω₂ are simple easy, so providing alternative proof of easiness for them.     

Decomposition in Terms of Variables for Some Optimization Problems

Decomposition of block convex-programming problems with coupling variables is considered in the paper. Functions of the blocks are defined on bounded sets. Rules for calculating -subgradients of objective functions of subproblems with connected variables are formulated. Initial problem normalization is described.     

Splitting Methods for Three-Dimensional Transport Models with Interaction Terms

We investigate the use of splitting methods for the numerical integration of three-dimensional transport-chemistry models. In particular, we investigate various possibilities for the time discretization that can take advantage of the parallelization and vectorization facilities offered by multi-processor vector computers. To suppress wiggles in the numerical solution, we use third-order, upwind-biased discretization of the advection terms, resulting in a five-point coupling in each direction. As an alternative to the usual splitting functions, such as co-ordinate splitting or operator splitting, we consider a splitting function that is based on a three-coloured hopscotch-type splitting in the horizontal direction, whereas full coupling is retained in the vertical direction. Advantages of this splitting function are the easy application of domain decomposition techniques and unconditional stability in the vertical, which is an important property for transport in shallow water. The splitting method is obtained by combining the hopscotch-type splitting function with various second-order splitting formulae from the literature. Although some of the resulting methods are highly accurate, their stability behaviour (due to horizontal advection) is quite poor. Therefore we also discuss several new splitting formulae with the aim to improve the stability characteristics. It turns out that this is possible indeed, but the price to pay is a reduction of the accuracy. Therefore, such methods are to be preferred if accuracy is less crucial than stability; such a situation is frequently encountered in solving transport problems. As part of the project TRUST (Transport and Reactions Unified by Splitting Techniques), preliminary versions of the schemes are implemented on the Cray C98 4256 computer and are available for benchmarking.     

一种语言值关联规则刷洗方法

通过给定的最小支持率和最小信任度来挖掘语言值关联规则往往会得到很多规则,而且这些规则之间存在一定的冗余,因此需要对语言值关联规则进行筛选.提出一种基于遗传算法的语言值关联规则筛选方法.此方法首先对语言值关联规则进行二进制编码,并通过遗传算法全局搜索一组语言值关联规则,使得对所有样本点的线性平均误差最小.实验表明,算法能够大量减少语言值关联规则的数量,并筛选出对用户更有用的语言值关联规则     

利用关联规则挖掘文本主题词的方法

主题词抽取是目前信息检索领域研究的热点,与一系列数据挖掘相关的任务密切相关。该文提出一种新的利用关联规则挖掘中文文本主题词的方法,该方法抽取的主题词包括关键词和相关检索词两部分。在关键词抽取的基础上,采用数据挖掘中的关联规则挖掘算法抽取相关检索词,用于扩展检索或相关检索,提高了用户对于文档的理解。实验表明该方法取得了较好的效果。     

A Calculus of Terms for Coalgebras of Polynomial Functors

A syntax and semantics of types, terms and formulas for coalgebras of polynomial functors is developed, extending earlier work [4] on monomial coalgebras to include functors constructed using coproducts. A modified ultrapower construction for polynomial coalgebras is introduced, adapting the conventional ultrapower to retain only those states that evaluate observable terms in a standard way.A special role is played by terms that take observable values and are “rigid”: their free variables do not occur in any state-valued subterm. The following “co-Birkhoff” theorem is proved: a class of polynomial coalgebras is definable by Boolean combinations of equations between rigid terms iff the class is closed under disjoint unions, images of bisimulations, and observable ultrapowers.     

Choices in Representation and Reduction Strategies for Lambda Terms in Intensional Contexts

Higher-order representations of objects such as programs, proofs, formulas, and types have become important to many symbolic computation tasks. Systems that support such representations usually depend on the implementation of an intensional view of the terms of some variant of the typed lambda calculus. New notations have been proposed for the lambda calculus that provide an excellent basis for realizing such implementations. There are, however, several choices in the actual deployment of these notations the practical consequences of which are not currently well understood. We attempt to develop such an understanding here by examining the impact on performance of different combinations of the features afforded by such notations. Among the facets examined are the treatment of bound variables, eagerness and laziness in substitution and reduction, the ability to merge different structure traversals into one, and the virtues of annotations on terms that indicate their dependence on variables bound by external abstractions. We complement qualitative assessments with experiments conducted by executing programs in a language that supports an intensional view of lambda terms while varying relevant aspects of the implementation of the language. Our study provides insights into the preferred approaches to representing and reducing lambda terms and also exposes characteristics of computations that have a somewhat unanticipated effect on performance.