基于范畴论的素描数据模型

针对关系数据库语义表达的不足,讨论了一种语义数据模型--基于范畴论的素描数据模型,从素描数据模型的形式化定义出发,以一种非形式化的方法分析了素描数据模型的基本概念,为更好地使用素描数据模型提供了基础.     

基于范畴论的形式语言模型建模方法研究

形式语言模型转换的语义一致性与其形式系统完备性分析是当前形式语言理论尚未有效解决的难题。针对形式语言模型的应用需求与研究现状,建立形式文法模型及其形式语言模型,应用范畴论方法构建具有普适意义的形式文法模型范畴与形式语言模型范畴。在形式语言族模型的形式化理论框架内,用与特定形式语言无关的范畴论方法研究形式语言模型转换的语义一致性。初步分析形式系统的完备性,通过与形式语言理论主要研究方法的比对论证了范畴论方法的优势,为形式语言模型的范畴论方法研究提供一个便利、高效的形式化理论框架。     

形式语言基于Monads的语义计算模型

传统形式语言的语义建模方法在语义解释与规则描述等语义计算方面存在不足,应用范畴论方法的Monads对形式语言的语义计算进行了研究。基于Monads构造Kleisli范畴,在Kleisli范畴的形式化框架内建立语义计算模型,并对该模型进行了应用。与传统语义建模方法相比,所提语义计算模型具有普适性,其语义解释与规则描述的能力更强。     

一种时态数据形式语言模型

数据模型是数据库技术发展的主线,时态数据模型是时态数据库系统的核心与基础。针对时态数据模型的研究现状,初步探讨了时态数据模型的基本要素,建立了一种形式化时态数据模型;基于形式语言理论和形式语义学的指称语义方法,进一步建立了该时态数据模型的形式语言模型。应用时态数据形式语言模型定义了各类时态完整性约束的形式语义规则,深入分析了时态数据模型内在的时态语义联系,为时态数据模型的研究提供了一个便利、高效的形式化理论框架。     

基于Fibrations理论的共享系统数据模型

传统共享系统数据模型的建模方法在语义性质分析和语义行为描述方面存在不足,针对以上问题提出了一种基于Fibrations理论的共享系统数据模型。主要工作体现在两个方面:首先,应用真值函子、保持真值的提升与内涵函子并结合代数方法精确分析了语义性质,应用等式函子、保持等式的提升及商函子并结合共代数方法形式化描述了语义行为;其次,在Fibrations理论框架内构造复杂归纳与共归纳数据结构上参数化的递归与共递归操作,抽象描述具有普适意义的归纳与共归纳规则,结合实例简要介绍了Fibrations理论的应用。相对于范畴论等传统方法,简洁描述与灵活扩展的Fibrations理论对共享系统数据模型的语义性质和语义行为进行了精确分析与形式化描述,抽象描述了复杂数据结构具有普适性的归纳与共归纳规则。     

构件式体系结构模型映射的形式化语义

语义一致性是模型驱动开发中模型转换正确性的一个重要标准,但目前模型转换中语义特性保持的定义、描述和验证仍是一个尚未解决的难题.基于软件体系结构,利用范畴理论和代数规范形式化描述体系结构模型及其间的映射关系,使之具有精确的语义.体系结构模型的形式化语义用类型范畴图表来表示,态射合成被用来追踪构件模型之间的关联和映射,不同层次模型间的映射关系用态射和函子来形式化描述.以此为基础,进一步分析了模型转换应保持的语义特性.范畴理论支持图形化建模,可以使模型中的构件关系以及结构特征可视化,有利于对模型转换的理解和追踪.应用研究表明,该描述框架很好地把握了模型驱动开发的实质、过程和要求,为模型转换和模型驱动开发提供了新的认知、设计和语义计算的指导架构.     

支持模型驱动开发的软构件形式化描述方法

针对模型驱动的软件开发(MDSD)中语义特性保持的描述和验证等问题,基于类型范畴理论的形式化框架和进程代数理论,提出了一种软件结构模型的形式化描述方法。在此基础上对模型转换前后构件规范之间应满足的语义约束进行了深入的分析和探讨,从图表结构、端口与配置约束、外部行为以及可替换性等四个方面对特性约束保持的问题进行了描述,并建立了相应的判定标准。该方法能为模型之间转换规则的定义提供指导,并为模型转换的效果分析和正确性验证提供依据。应用研究表明,该方法使得构件模型的语义描述能力显著增强,可作为已有软件建模方法的一个有效补充。     

以体系结构为中心的模型转换的语义描述框架

在对类型范畴理论进行扩展的基础上,将其与进程代数相结合,为软件体系结构模型及其间的转换关系提供了一种统一的语义描述框架.模型的结构语义由类型范畴图表来指代,其行为语义则由范畴附带的进程行为迹来表示,模型间的映射关系用范畴理论中的态射和函子来形式化描述.该描述框架可用于模型转换中特性保持问题的描述、分析和判定,从而为模型驱动的软件开发提供有力的支持.     

一种异构数据源模型转换和模式集成框架

异构数据源集成系统的主要任务是屏蔽数据源数据模型的异构性,提供对数据的统一访问。公共数据模型、模型变换和中间数据模型被广泛用来解决该问题。由于数据集成工作的工作量和任务对象日益复杂、规模日趋庞大,仅采用公共数据模型不能满足现有集成要求。异构数据源数据模型内在的关联性虽然使得面向语义集成变得更加复杂,但更利于模型转换方法在数据集成中的应用。模型转换是模式集成的基础,本文给出了异构数据源模型的形式化描述方法和基础模型转换操作形式化框架。该框架能够保证模型、实例和约束三者的相互独立,适用于大多数基础数据模型及其之间的转换和集成应用。通过该框架可简化和规范异构数据源数据模型转换和模式集成过程。     

时态数据库的可视化方法与技术

1 引言时态数据库是将时间的概念结合到传统的数据库中。近十年来,人们对此所作的许多研究主要集中在把关系数据模型扩展为时态模型以及(或)把关系查询语言SQL和Quel扩展为时态的模式。除了强调关系模型之外,也有一些研究是将ER和其他的语义数据模型扩展到时态方面。时态数据模型的形式化和时态数据库的物理数据组织结构也受到了人们的关注。     

Enriching the ER model based on discovered association rules

The entity-relationship (ER) model, a powerful means for business and data modeling, needs to be enriched with new semantics as the real world changes and its understanding improves. This paper attempts at enriching the ER model based on association rules (AR) discovered from large databases by introducing specializations and sub-types into the ER model. The proposed framework is extended to deal with more general, flexible and linguistic knowledge in fuzzy association rules. Moreover, transforming an AR-enriched-ER (AR-EER) schema to a relational database (RDB) schema is also investigated.     

UML动态模型在关系数据库操作中的应用

UML作为一种面向对象的标准建模语言,在关系数据库系统的建模领域也得到了广泛的应用.用UML为关系数据库模式建立的模型比ER模型表达力更强,但目前的UML数据库建模技术主要强调静态模型.概述了如何使用UML动态建模方法为关系数据库操作建模.在建立的框架的基础上可为原子数据库操作建模,进而为更复杂的数据库操作建模.这种方法将为用户和开发者提供对整个系统的一个统一视角,将UML的强大功能扩展到数据库领域.     

Sketch-based 3D model retrieval by incorporating 2D-3D alignment

Sketch-based 3D model retrieval is very important for applications such as 3D modeling and recognition. In this paper, a sketch-based retrieval algorithm is proposed based on a 3D model feature named View Context and 2D relative shape context matching. To enhance the accuracy of 2D sketch-3D model correspondence as well as the retrieval performance, we propose to align a 3D model with a query 2D sketch before measuring their distance. First, we efficiently select some candidate views from a set of densely sampled views of the 3D model to align the sketch and the model based on their View Context similarities. Then, we compute the more accurate relative shape context distance between the sketch and every candidate view, and regard the minimum one as the sketch-model distance. To speed up retrieval, we precompute the View Context and relative shape context features of the sample views of all the 3D models in the database. Comparative and evaluative experiments based on hand-drawn and standard line drawing sketches demonstrate the effectiveness and robustness of our approach and it significantly outperforms several latest sketch-based retrieval algorithms.     

CGOOD, a categorical graph-oriented object data model

While the relational data model and many of its extensions have proven to be of considerable importance to many database applications, it has become clear that some advanced systems require more flexible structures and query languages. The expression of queries based on the occurrence of substructures on instance level (i.e., pattern matchings) requires constructs which cannot be expressed easily in the traditional models.

In this article, we introduce an object-oriented data model which solves these shortcomings. The instances of this data model will be represented by typed graphs. Both scheme and data will be defined entirely in terms of categorical constructs; pattern matching of graphs will be realized by morphisms in a suitable graph category. These morphisms will be used to define a powerful query and update language, which is capable of querying and restructuring the database in a natural and elegant way. Finally, we show that this query language is able to express the relational database operators, functional abstraction and transitive closure.

It will become clear that the categorical approach provides a solid basis for data modeling because it offers a unifying, theoretical framework. The abstractive power of the categorical framework creates an environment which sheds new light upon existing concepts and is the source of many interesting generalizations. The capability to make abstraction of low-level details, moreover, will often simplify the proofs of many theorems which would be rather involved and confusing in the traditional frameworks.     

基于Agent的分布式模型形式化语义描述

为解决分布式系统构建过程中系统组合和语义验证等方面的问题,基于范畴理论和进程代数,为基于Agent的分布式系统模型提出了一种形式化的语义描述框架。范畴图表用于描述整个系统的结构模型,态射用来表示系统各组成部分之间的交互和协作机制。在此基础上,对Agent规范的描述、组合、精化以及迁移过程中的语义保持问题进行了探讨。应用研究表明,该框架适用于分布式系统模型的描述和构建,有助于分析系统分解和组合的正确性。     

A formal approach to object-oriented databases

Object-oriented database systems are the focus of current research and development efforts. Yet, there is no commonly accepted object model, nor is it clear whether such a model can be developed. This paper reports on efforts to develop a formal framework that contains most features found in current object oriented database systems. The framework contains two parts. The first is a structural object model, including concepts such as structured objects, identity, and some form of inheritance. For this model, we explain the distinction between values and (abstract) objects, describe a system as a directed graph, and discuss declarative languages. The second part deals with higher-order concepts, such as classes and functions as data, methods, and inheritance. This part is a sketch, and leaves many issues unresolved. Throughout the paper, the emphasis is on logic-oriented modeling.     

The category concept: An extension to the entity-relationship model

An enhanced version of the Entity-Relationship (ER) data model called the Entity-Category-Relationship (ECR) data model is presented. The principal extension is the introduction of the concept of a category. Categories permit the grouping of entities from different entity types according to the roles they play in a relationship, as well as the representation of ISA and generalization hierarchies. The structures of the ECR data model are defined, and a graphic representation technique for their display is presented. Language operations to define and use an ECR database are defined. Two realistic examples of the use of the ECR model for database design are demonstrated. The examples show how ECR structures can be directly mapped into relational and network structures. The definition of derived relationships on an ECR database gives the power to phrase higher order recursive queries in a first order query language.     

一个拟PETRI网建模模型

本文利用ＰＥＴＲＩ网和自动机理论，为ＥＡＲ数据模型的数据库设计，建立一个拟ＰＥＴＲＩ网的设计方法，并构造一个建模模型，为数据库辅助设计提供基础框架结构。