类型系统与程序正确性问题

类型系统能检出合法程序的语义错误，可以缩短调试时间，在执行程序之前捕获代码中的错误。类型系统的理论基础是类型化的λ演算。带子类型的高阶类型系统腿已成为类型化语言的演算核心。类型系统和直觉主义极小逻辑是同构的。证明系统的能力取决于类型系统，因而类型系统可以表迭程序的性质，并自动进行验证。     

基于类型理论的面向对象多步证明系统

介绍基于扩展构造型演算的交互式多步证明系统。该系统中以函数式语言ML为开发环境，建立了ECC的项、规则证明策略和证明管哩机制的描述，并引入规约类型、类类型、类和对象的表示，为面向对象的程序规约和定理证明系统的结合进行了一些探索。     

类型系统的λω×≤等式理论及其语义的合理性

类型系统在研究程序设计语言的理论基础方面起着十分重要的作用,特别地,带子类型的多态类型系统可刻画面向对象程序设计语言核心概念,如子类型、多态性等.为研究面向对象程序设计语言的形式理论基础,探讨了一个命名为类型系统λω×≤的带高阶子类型的多态类型系统,并利用插入子和fibration理论,引入λω×≤fibration作为该类型系统的语义模型.进一步,讨论了类型系统λω×≤的等式理论,特别是与受限全称量词有关的等式,并利用插入子的性质,证明了对于该等式理论,λω×≤fibration是合理的语义模型.     

面向对象语言中子类型的代数模型

本文提出的类型和子类型的代数概念适合于建立严格的面向对象的继承性模型。按保特性强制映射定义的“子类型”是代数间的一种二元关系,该映射具有有关函数类型、记录类型和继承的良好的组合特性。代数模型与二阶(多态)λ演算中的子类型多态性的模型相关。本文还介绍了有界量化的表示,并考察了它在模型化继承中的应用。     

基于类型理论的面向对象多步证明系统

介绍基于扩展构造型演算的交互式多步证明系统。该系统中以函数式语言ＭＬ为开发环境，建立了ＥＣＣ的项、规则证明策略和证明管理机制的描述，并引入规约类型、类类型、类和对象的表示，为面向对象的程序规约和定理证明系统的结合进行了一些探索。     

面向对象系统的分类

我们用分类机制来表征面向对象系统,因为它们在分类模式上是规定的,而对通讯和信息传送机制却是未作规定的。它们把传统类型系统的平展分类机制扩充到具有公用操作和属性的树状类型集。我们把分类模式与通讯及状态变换模式联系起来评述生物分类和面向对象分类两者之间的关系,并研究其演算及代数的实现方法。面向对象类型系统确定的类演算弱于以代数模型[BW]或用二阶多态,λ演算作模型[CW]的值的演算。有关技术性细节较为全面的讨论可在[We]中找到。     

一种带有delegation的对象演算

随着研究与应用的深入，传统的基于类的面向对象语言对动态变化要求的支持不足越来越明显。而且，由于软件系统复杂性的不断提高，这个问题变得更加突出。近年来，人们一直在进行着各种研究和尝试，寻求解决办法。delegation是一种在基于原型的面向对象语言中实现的对象动态继承，由于它支持对象行为在运行期动态改变，能提供对象动态扩展功能的能力，因此探讨如何在基于类的面向对象语言中引入delegation成分，以提供软件运行时刻的结构与行为变更能力，是十分有意义的。本文提出了一种命令式、带有delegation的西对象演算，以该演算系统刻划程序设计语言的基本特征；通过给出西演算的语法和操作语义；详细描述程序中各种操作的实现方法；着重说明在程序语言中引入delegation成分后，对象之间共享方法和对象扩展功能所具有的灵活性和简单性。从而说明在程序语言中引入delegation，以支持软件动态变更是一种有效且可行的途径。     

从SmalltaIk语言的结构特征看“软插件”的形成

<正> 一、引言软件的可重用性是软件工程领域中的一个重要课题,现已经有许多人在探索软件可重用的途径,面向对象的程序设计方法则是以解决软件可重用性问题作为自己的重要目标之一。另外,Smalltalk语言经过十几年的实践,走向了成熟,开始为广大程序人员所欣然接受,国内已有相当数量的软件工作者开始研究该语言。我们在VAX-11/780机上用C语言实现了Smalltalk-80系统的核心环境,深受Smalltalk语言其独特构造的启发。本文从Smalltalk语言的结构分析出发,提出了“软插件”的概念,并探讨了此概念形成和实用的可能性,以及它在软件可重用领域中的实践意义,最后,讨论了面向对象方法与“软插件”概念的必然联系。     

类型化面向对象程序设计风格体现于ML语言

本文探讨在运用ML语言中体现面向对象的程序设计风格。更有意义的是,利用ML语言的“隐式类型化及同式多型自动类型检验系统”,赋予面向对象程序设计风格以同式多型的类型化,从而,达到类型化的面向对象程序设计风格。     

一种基于ADT的函数语言及其操作语义模型

本文介绍一以ＡＤＴ为主要构件的函数语言，它是作者设计的函数式及面向对象式合成语言的函数部分，进而描述了其操作语义模型：多态λ演算十代数重写系统＝多态λ重写系统，并讨论该模型的Ｃｈｕｒｃｈ－Ｒｏｓｓｅｒ性质和强范式性质。     

考虑类型信息的异构数据源信息交换方法研究

异构信息源模式集成中,除解决模式结构冲突外,还需要考虑模式结构对应的数据类型差异,以保证模式集成和信息交换过程的准确性.本文在考虑不同模型语言类型约束和复合对象类型的基础上形式化描述了类型体系,在公共类型体系内容定义的基础上给出了考虑约束和复合对象类型的中间模型类型体系的构建方法,建立了异构数据模式类型体系与中间模型类型体系的类型映射关系.相比其他类型匹配方法,具有搜索空间小、处理范围广的特点.     

CLS到IDL的语言类型系统映射研究

NET框架和CORBA系统在集成互操作中，必然要求语言的映射。语言映射中首要和基础的工作是双方的类型系统的映射。在文中，对．NET框架中的CLS语言到OMGIDL语言的映射必要性、类型系统映射的分类以及与实例转换的区分进行了分析，研究了具体的CTS类型映射到IDL类型，对于映射中遇到的问题给出了处理方法，从而定义了可以被映射的CLS的子集，并指出了在语言映射需要进一步研究的问题。     

一类递归函数的多态类型

以上下文无关语言上的递归函数为基础的语言LFC(1anguage for context free recursive function)是一种形式规约语言,适于处理短语结构.LFC也是函数式语言,具有函数式语言的许多特点.LFC已经在形式规约获取系统SAQ(specification acquisition system)中实现,为其最初设计的类型系统不支持多态类型.引入类型变量和相应的类型检查方法,就可以将其类型系统扩充为多态类型系统.对多态类型系统实现中的一些问题也进行了讨论.在实现多态之后,LFC     

Kinded type inference for parameteric overloading

Parameteric overloading refers to the combination of parameteric polymorphism and overloading of polymorphic operators. The formal basis for parametric overloading, proposed by Kaes and extended by Wadler and Blott, is based on type predicates. In this paper another approach to type-checking for parameteric overloading is proposed. The resulting type system loosens some of the restrictions required of overload instance types for type-checking, while also providing fresh insight into type-checking for parameteric overloading. In this system, the kind for a type variable characterizes the set of closed type expressions which may be substituted for that variable. A theory of equality and subkinding for this system is presented, and algorithms for emptiness-checking, subkinding and intersection are provided. This kind system is used as the basis for an extension of Milner's W algorithm for ML-style type inference to kinded type inference. Finally the kinded type system is verified to be sound and complete with respect to the system of type predicates proposed by Wadler and Blott. Received: 11 May 1993 / 28 November 1994     

Discrete Interval Type 2 Fuzzy System Models Using Uncertainty in Learning Parameters

Fuzzy system modeling (FSM) is one of the most prominent tools that can be used to identify the behavior of highly nonlinear systems with uncertainty. Conventional FSM techniques utilize type 1 fuzzy sets in order to capture the uncertainty in the system. However, since type 1 fuzzy sets express the belongingness of a crisp value x' of a base variable x in a fuzzy set A by a crisp membership value mu_A(x'), they cannot fully capture the uncertainties due to imprecision in identifying membership functions. Higher types of fuzzy sets can be a remedy to address this issue. Since, the computational complexity of operations on fuzzy sets are increasing with the increasing type of the fuzzy set, the use of type 2 fuzzy sets and linguistic logical connectives drew a considerable amount of attention in the realm of fuzzy system modeling in the last two decades. In this paper, we propose a black-box methodology that can identify robust type 2 Takagi-Sugeno, Mizumoto and Linguistic fuzzy system models with high predictive power. One of the essential problems of type 2 fuzzy system models is computational complexity. In order to remedy this problem, discrete interval valued type 2 fuzzy system models are proposed with type reduction. In the proposed fuzzy system modeling methods, fuzzy C-means (FCM) clustering algorithm is used in order to identify the system structure. The proposed discrete interval valued type 2 fuzzy system models are generated by a learning parameter of FCM, known as the level of membership, and its variation over a specific set of values which generate the uncertainty associated with the system structure     

一种光电式电子白板的技术解析

对比电阻式电子白板、电容式电子白板、红外式电子白板、超声波式电子白板、CCD光扫描式电子白板和电磁感应式电子白板的优缺点,详细论述了光电式电子白板的光电笔的设计、图像处理系统的设计,以及它们的软件系统,指出了改进和发展的方向.     

现场总线本安型防爆系统在煤矿自动化系统中应用的可行性分析

介绍了现场总线本安型防爆系统在石化领域及煤炭生产自动化系统中的应用现状,提出了现场总线本安型防爆系统在我国煤炭生产自动化系统应用中存在的问题,指出现场总线本安型防爆系统应用于我国煤炭生产自动化和通信系统中是可行的,但需制定适合我国煤炭生产的现场总线协议标准,认证方式应由系统认证方式转变成参量认证方式。     

A Relational Representation of an Abstract Type System

Programming languages have traditionally had more data types than database systems. The flexibility of abstract types could make a database system more useful in supporting application development. Abstract types allow users to think about and manipulate data in terms and structures that they are familiar with. This paper proposes that databases have a type system interface and describes a representation of a type system in terms of relations. The type system model supports a variety of programming language constructs, such as user-defined parameterized data types and user-defined generic operations. The efficiency of the type system is compared to the access time of the database system.     

Richer types for Z

The formal specification language Z is strongly typed, but has a rather inexpressive type system in which essentially the only type constructors are power set and Cartesian product. This paper explores the possibility of using a richer type system for extracting information about a Z specification, so that properties like being a function or a sequence become part of the type of an expression. This richer type system adds further type constructors to the sparse set contained in the language definition, and uses properties of Z's library functions to infer information about complex expressions from information about their simpler parts.     

Behavioural typing for safe ambients

We introduce a typed variant of Safe Ambients, named Secure Safe Ambients (SSA), whose type system allows behavioral invariants of ambients to be expressed and verified. The most significant aspect of the type system is its ability to capture both explicit and implicit process and ambient behavior: process types account not only for immediate behavior, but also for the behavior resulting from capabilities a process acquires during its evolution in a given context. Based on that, the type system provides for static detection of security attacks such as Trojan Horses and other combinations of malicious agents.We study the type system of SSA, define algorithms for type checking and type reconstruction, define languages for expressing security properties, and study a distributed version of SSA and its type system. For the latter, we show that distributed type checking ensures security even in ill-typed contexts, and discuss how it relates to the security architecture of the Java Virtual Machine.