存储于关系数据库的知识库的语义推理方法

语义推理的功能使得知识库更具人工智能,具有实用意义。文章根据语义模型的特点,构建了基于关系数据库的知识库语义存储体系,该存储体系的模式空间和实例空间相分离,降低了结构和数据的耦合性,使语义的存储范围更具完整性、语义的推理效果更具智能性。面向该存储体系的语义推理方法实现了相关语义(专家知识)的推理和相似语义(词汇)的推理,同时,该方法也考虑到了推理范围的可控能力和推理结果的语义还原能力。分析表明,该方法能应用于实际,但仍存在一些可改进之处。     

计算机网络设计中关系数据库技术的应用

随着信息化技术的发展,计算机网络设计逐渐兴起并讯速发展。在计算机网络设计过程中,其工序相当复杂,因此需要建立与其相关的数据库保障计算机网络设计。关系数据库技术根据数据库中数据的相关性储存、调度数据,从而使其更好地服务于计算机网络设计。本文简要论述了关系数据库的概况、关系数据库在计算机网络设计中的辅助功能,分析了关系数据库技术在计算机网络设计中的基本原理并探讨了它在计算机网络设计中的优势。     

Semantics,dynamics tradeoff in relational database design

This paper gives some objections to the artificial separation of the semantics and dynamics aspects of the application during the database design process. It is suggested that both aspects of the application should play a role throughout the design stages (logical and physical) in order to produce a workable schema that captures the real usage picture of the intended application. A simple method that “trades” semantics and dynamics is proposed to provide a common yardstick to measure the “goodness” of the database design. To narrow the scope of the problem a bit, we will concentrate on the database design for the relational model.     

Correctness issues for distributed relational database design

This paper examines correctness issues that arise in distributed database design. A distributed relational database design is traditionally considered to be valid if every global relation can be reconstructed from its fragments by join operations. In this paper, three successively less restrictive definitions of validity are presented, each providing progressively improved handling of incomplete information. Examining these forms, a hybrid reconstruction approach involving inner- and outer-joins is proposed and we briefly describe its application to query formulation.We also propose replacing the notion of global reconstructability with the less restrictive, yet intuitively natural notion of object reconstructability. Universal relations need not be constructed. The need for maintenance of constraints across sites of a distributed system is discussed, and the notion of adistributed referential constraint is proposed which fulfills this need. Recommended by: Clement Yu     

关系数据库技术在计算机网络设计中的运用

随着我国社会经济建设水平的不断提高和计算机网络技术的推广普及,关系数据库技术在计算机网络设计中的运用成为社会各领域关注的焦点,本文将从关系数据库技术的角度出发,结合计算机网络设计的实际,对关系数据库技术在计算机网络设计中的运用进行深入的研究和探讨。     

Framework design of a domain-key schema of a relational database

A new approach to the synthesis of the domain-key normal form (DK/NF) for an arbitrary domain is proposed. The Cartesian dependency, which is a special case of multivalued dependencies, is investigated. A lemma on the non-abnormality of a special relational and a theorem on the non-abnormality of the actual part of a relational framework are proved. A new criterion for determining the belonging of a database schema to DK/NF is given. The proposed approach can be used in designing information warehouse schemas.     

The design and implementation of a road safety relational database

Road safety can be measured by the rate of road traffic accidents that occur periodically. In developing countries, one major problem confronting researchers in the area of road safety is that the sources of data collection are not centrally controlled. The proliferation of the sources of data collection leads to data incompatibility, incorrectness, inconsistency and redundancy. These, in turn, lead to inaccurate and conflicting statistics generated and published by different research groups. In this paper, a relational database to support road safety system and a technique for its implementation are presented. It is shown how the database can be processed and accurate statistics about road safety generated and analysed to support planning, decision making and control of operations by the authorities involved in road safety.     

An improvement on the automatic tool for relational database design

This paper corrects some misconceptions regarding an automatic tool for relational database design. A modified algorithm (SYNTHESIZER+) from the synthesis algorithm SYNTHESIZER is presented. For a given set of FDs, it can produce a third normal form (3NF) relational database schema with a minimum number of relations.     

A group-select operation for relational algebra and implicationsfor database machine design

A group-select operation has been defined for relational algebra. This operation is found to be useful for efficiently reducing expressions of nonprocedural relational languages that permit natural quantifiers. Conceptually, the operation first partitions a relation into blocks of tuples that have the same value for an attribute or attribute concatenation. It then extracts each block for which a specified number of tuples meet a specified condition. The quantity of tuples for the operation is specified by means of a natural quantifier. Performance of the group-select operation will be poor with conventional file processing, making the operation more suitable for use with a database machine with an associative memory     

Semantic integrity support in SQL:1999 and commercial (object-)relational database management systems

The correctness of the data managed by database systems is vital to any application that utilizes data for business, research, and decision-making purposes. To guard databases against erroneous data not reflecting real-world data or business rules, semantic integrity constraints can be specified during database design. Current commercial database management systems provide various means to implement mechanisms to enforce semantic integrity constraints at database run-time. In this paper, we give an overview of the semantic integrity support in the most recent SQL-standard SQL:1999, and we show to what extent the different concepts and language constructs proposed in this standard can be found in major commercial (object-)relational database management systems. In addition, we discuss general design guidelines that point out how the semantic integrity features provided by these systems should be utilized in order to implement an effective integrity enforcing subsystem for a database. Received: 14 August 2000 / Accepted: 9 March 2001 / Published online: 7 June 2001     

Semantic database prototypes

Abstract. This paper describes a technique for improving the semantic consensus of conceptual database designs. Semantic consensus is a condition where there is pragmatic agreement among database designers and all of the users about which aspect of reality is being represented by a particular database element, and how that representation is being coded. The technique, called semantic database prototyping (SDP), involves a prototype that has been designed and constructed purely as a consequence of the semantic data model. The purpose of the semantic database prototype is to promote direct user validation during the conceptual database design phase of information systems analysis and design. Its distinguishing characteristic is its capture of data element occurrences within the context of the database design. The research method was action research, and the project is also briefly described.     

Building systems on relational database

Relational databases are becoming increasingly popular. They create an environment within which computer system developers can use high level tools to build application systems quickly. This article looks at one computer manufacturer, Microdata, which has built a whole product line around the use of relational database products.     

Beyond the relational database model

The relational model is a set-theoretic model for describing data constructs common in the business environment. Relational databases also minimize data duplication, which ensures data integrity and reduces storage requirements. Further, the relational model provides a way to represent variable-length constructs with fixed-length components. In addition, normalization theory is the basis of hundreds of papers and successful tenure applications. This ensured the academic community would carry the model forward. Finally, by following open standards, including the structured query language, vendors created a buzz with dozens of relational DBMS products such as System R, DB2, Oracle, SQL Server, Ingres, dBase, R:Base, Pearl, Paradox, and Access. An XDS have many advantages over a relational database, including seamless integration with user views as well as all the benefits of XML standards such as XML schema validation and the extensible stylesheet language for document materialization.     

Hierarchical to relational database migration

Although database migration has not yet been extensively researched, three predominant software solutions have evolved: language interfaces, source-code conversion, and data propagation. The authors consider how Swiss Bank and IBM designed and developed the IBM Data Propagator MVS/ESA, which supports interactive and batch data propagation. This software migrates data from the hierarchical IMS to the relational DB2, without affecting existing applications. It supports forward and reverse data propagation, which lets heterogeneous databases coexist. At Swiss Bank, the Data Propagator MVS/ESA handles the main customer and account databases at all five computer centers in Switzerland     

粗糙关系数据库的数学基础

在引入粗糙关系数据库（Rough Relational Database,RRDB）的基本概念基础上,分析得出粗糙关系数据库中使用的几个主要数学理论包括等价关系、分解、位模式、粗糙熵及粗糙集理论,并进一步深入研究了这些理论在RRDB中的相关性质,对它们在粗糙关系数据库中的应用进行了探讨。