基于本体的语义虚拟环境查询与推理模型

当前将本体引入到语义虚拟环境的研究,只是将领域本体的可视化信息用本体表示,并未发挥本体本身具有的优势。为此,提出一种基于本体的语义虚拟环境查询与推理模型。利用OWL语言统一描述虚拟场景图形内容与语义信息,并分别对两者进行查询,在图形内容查询过程中引入本体的推理方法推理出隐含的图形内容信息,然后查询需要的信息。在语义信息查询时引入语义搜索方法,利用基于语义距离计算本体概念相似度的方法计算语义虚拟环境本体中类之间的相似度,搜索与被查询实例语义相似度最大的实例,并借助推理找出其间的关系。对语义虚拟家具商店进行本体的查询与推理,结果证明了该模型的可行性。     

基于图数据库的RDF数据分布式存储

RDF数据模型具有天然的图结构,因此以图结构存储可以避免RDF逻辑数据模型到物理数据模型的转换。基于图数据库的RDF数据分布式存储方案,重点讨论RDF图数据流分割、图数据库分布式扩展、SPARQL查询语言转CYPHER图形查询语言等。实验对比了基于Neo4j图数据库与基于MySQL关系型数据库的RDF数据存储方案的处理性能,并验证了RDF图数据流分割算法的有效性。     

支持XML查询代数和树模式查询的XQuery系统框架

XQuery语言的高性能实现需要利用XML查询代数提供的查询优化方法,也需要采取高效的树模式整体匹配算法。为了将这两种XML查询处理技术有效地结合在XQuery语言处理系统中,提出了一种通用系统框架来支持XQuery语言的高性能实现。在这个框架内,提供开放式XML数据源连接,并且通过作为中间语言的一种函数式查询计划描述语言FXQL来支持各种查询代数算子和树查询模式的表示,既允许采用各种XML查询代数,又允许采用各种树模式查询算法;进而,通过这种中间层的程序变换可以实现基于各种查询代数的查询重写,并从查询计划中分离出独立的树模式查询计算,使两种查询处理技术适当地统一在同一系统框架中,有效地支持了多种环境下XQuery语言的实现。     

可视化空间数据库查询语言CQL

本文着重从语法、语义及语用三方面介绍了我们所开发的一个可视化空间数据库查询语言ＣＱＬ。该语言允许用户借助于可视化基本元素－－－卡片进行编程,实现对窨数据库的检索。用户查询语句是这些卡片的空间组合。该语言对查询结果的表示提供了多种形式：图形表示形式、正文表示形式、临时文件或三者的组合形式。     

一个可视知识查询语言CAOBS／VKQL

介绍的ＣＡＯＢＳ／ＶＫＱＬ是一个可视知识查询语言，它以灵活，直观，方便的图形操纵方式提供给用户访问、查询知识库的强大能力。该语文的查询模型以ＲＩＫＯＭ知识模型为基础，用户通过构造查询图来表达查询要求。     

基于语言分类的P2P覆盖网络

基于Web语言分布和P2P中共享信息的特点,提出了一个基于语言类别的P2P覆盖网络。该方法通过对节点共享信息的语言进行识别,将节点根据不同的语言类别进行组织,查询时对查询问题进行同样的分类,并在对应语言类别中进行查找。仿真表明,该方法有效地提高了不同语言用户的查询成功率,同时便于已有语义分析技术在P2P网络中的进一步应用。     

基于XML的半结构数据查询语言研究

半结构数据管理的核心问题之一是数据的有效查询问题。文章重点分析、比较了两种基于XML的半结构查询语言,即XQL和XML-QL。在此基础上总结出了XML查询语言的基本需求,并对目前的XML查询语言提出了四点扩充建议。     

XML查询的代数表示及其查询优化

本文绘出了一种XML查询的逻辑代数表示,基于这种代数表示作者探讨了在逻辑层面上进行XML查询优化的可能性和方法。文章按以下方式组织,第一部分给出了一种XML数据的模型表示,接着简单描述了在这个模型上的XML查询语言-AnXQL;第二部分是本文的重点,详细描述了XML查询的逻辑代数操作符,并举例说明;第三部分在逻辑层面上探讨了XML查询优化的方法;最后一部分介绍了相关研究工作,并与本文的方法进行了对比。本文是文[8]中基于半结构化数据模型的集成查询处理研究的重要组成部分。     

基于语义关系对的SVG图形搜索引擎

个性化图形搜索打破了传统的查询方式搜索,将基于关键词的查询方式转变为基于图形的查询方式,使图形的查询具有一定的语义关系,查询结果也更加准确。该文给出一种基于语义关系对的SVG图形搜索引擎。目前大多数浏览器不直接支持SVG图形,但通过该文提出的SVG图形解析器和SVG图形显示器可以对网络上的SVG图形进行检索和显示。     

基于Vague集的次协调数据库的研究

次协调数据库的数据模型是用来处理数据库中不完全信息和矛盾信息。基于这种数据模型,将Vague集的概念引入,并基于新模型重新定义选择、投影、连接及decision等运算,再使用基于Vague集的次协调数据库的查询语言（PQL）查询矛盾信息并作出决策以解决矛盾,从而扩展了传统次协调数据库模型的应用。     

面向对象知识库系统CAOBS／V1.2的可视化查询子系统

面向对象知识库系统ＣＡＯＢＳ／Ｖ１．２的用户界面是一个可视化知识查询子系统，它包括一个灵活、直观、方便的可视知识查询语言（ＶＫＱＬ）和一个知识库浏览编辑器。利用该可视化查询语言，用户可以通过构造查询图来表达查询要求，并最终实现查询功能。ＶＫＱＬ吸收了国际上现有的几种可视查询语言的优点，具有较强的查询功能，使用方便。文中介绍了ＶＫＱＬ的设计思想和实现技术，在最后一节将ＶＫＱＬ与同类查询语言进行了对比     

VISIONARY: a Viewpoint-based Visual Language for Querying Relational Databases

The adoption of a visual interface can simplify the query formulation process in DBMSs by enabling naive users to interact with a friendly environment. In this work, we propose a visual query language based on a diagrammatic paradigm, used for both data and query representation. The external data model is called vision and is made up of the visual primitives of concept and association. The external query model is based on the definition of a viewpoint, which is a perspective for accessing data defined dynamically by selecting a concept of primary interest. Internally, the data model is relational and the query language is SQL. An intermediate graph-based model ensures consistent mapping between the visual and the relational worlds. Our language has been implemented within a tool which can be mounted on top of any relational DBMS supporting ODBC. The system has been tested with naive users; the results of the experiment are reported and compared with those obtained with other visual languages.     

G-Log: a graph-based query language

We introduce G-Log, a declarative query language based on graphs, which combines the expressive power of logic, the modeling power of complex objects with identity and the representation power of graphs. G-Log is a nondeterministic complete query language, and thus allows the expression of a large variety of queries. We compare G-Log to well-known deductive database languages, and find that it is the only nondeterministic and computationally complete language that does not suffer from the copy-elimination problem. G-Log may be used in a totally declarative way, as well as in a “more procedural” way. Thus, it provides an intuitive, flexible graph-based formalism for nonexpert database users     

TEMPOS: a platform for developing temporal applications on top of object DBMS

We present TEMPOS: a set of models and languages supporting the manipulation of temporal data on top of object DBMS. The proposed models exploit object-oriented technology to meet some important, yet traditionally neglected design criteria related to legacy code migration and representation independence. Two complementary ways for accessing temporal data are offered: a query language and a visual browser. The query language, namely TEMPOQL, is an extension of OQL supporting the manipulation of histories regardless of their representations, through fully composable functional operators. The visual browser offers operators that facilitate several time-related interactive navigation tasks, such as studying a snapshot of a collection of objects at a given instant, or detecting and examining changes within temporal attributes and relationships. TEMPOS models and languages have been formalized both at the syntactical and the semantical level and have been implemented on top of an object DBMS. The suitability of the proposals with regard to applications' requirements has been validated through concrete case studies.     

Object-oriented query languages: the notion and the issues

The authors describe how the characteristics of an object-oriented data model, such as object identity, complex object structure, methods, and class hierarchies, have an impact on the design of a query language. They also point out major differences with respect to relational query languages. The discussion is supported through the definition of OOPC, a formal object-oriented query language based on predicate calculus, which incorporates in a consistent formal notation most features of existing object-oriented query languages     

Declarative XML Update Language Based on a Higher Data Model

With the extensive use of XML in applications over the Web, how to update XML data is becoming an important issue because the role of XML has expanded beyond traditional applications in which XML is used for information exchange and data representation over the Web. So far, several languages have been proposed for updating XML data, but they are all based on lower, so-called graph-based or tree-based data models. Update requests are thus expressed in a nonintuitive and unnatural way and update statements are too complicated to comprehend. This paper presents a novel declarative XML update language which is an extension of the XML-RL query language. Compared with other existing XML update languages, it has the following features. First, it is the only XML data manipulation language based on a higher data model. Second, this language can express complex update requests at multiple levels in a hierarchy in a simple and flat way. Third, this language directly supports the functionality of updating complex objects while all other update languages do not support these operations. Lastly, most of existing languages use rename to modify attribute and element names, which is a different way from updates on value. The proposed language modifies tag names, values, and objects in a unified way by the introduction of three kinds of logical binding variables: object variables, value variables, and name variables.     

一个基于图的音乐数据模型与查询语言及其实现

图数据模型广泛应用于各种具有复杂关联数据的领域.针对现有音乐数据模型与查询语言在功能上的缺陷,首先提出了一个基于图的音乐数据模型Gra-MM,用图数据模型对复杂音乐数据进行建模,定义了图逻辑数据结构以及相关的图代数操作,然后给出了建立在Gra-MM之上的音乐数据查询语言Gra-MQL,定义了查询语言的BNF定义.Gra-MQL能够较好地处理音乐数据之间的复杂关联,同时具有音乐元数据检索和音乐内容数据检索能力,从而满足用户对音乐数据不同层次的查询需求,克服了传统图数据查询语言对复杂关联数据的表达能力有限、不能直接应用于音乐内容检索等不足.最后对实现的音乐数据库原型系统进行了介绍,对原型系统进行测试并给出实验数据,证明了模型以及查询语言的可行性.     

QBD*: a graphical query language with recursion

A system to query databases using diagrams as a standard user interface is proposed. The system, called Query by Diagram* (QBD*), makes use of a conceptual data model, a query language on this model, and a graphical user interface. The conceptual model is the entity-relationship model. The query language, whose expressive power allows recursive queries, supports visual interaction. The main characteristics of the interface are ease of use and the availability of a rich set of primitives for schema selection and query formulation. The expressive power of QBD* and G⁺, which are the only languages allowing recursive queries to be expressed graphically are compared     

Query by diagram: A visual environment for querying databases

In recent years, several attempts have been made to define query languages characterized by both high expressive power and easy query formulation. Several issues concern graphical applications, based on the diagrammatic representation of a semantic model and visual interaction. This paper describes the architecture and the implementation of a graphical query system, based on the diagrammatic representation of entity relationship schemata. The query language underlying the system allows the formulation of recursive queries; moreover, user interaction in both managing diagrams and expressing queries is simplified by the presence of a fully visual environment and a rich set of interaction strategies.