一种基于Z和精化演算的形式化开发方法

通过分析Z和精化演算各自的特点,本文提出了一种使两者无缝集成的形式化开发方法。该方法利用Z良好的描述特性和扩充的类机制,将系统规约直妆定义成精化演算中的抽象程序,然后用精化规则对抽象程序逐步精化,直到可执行程序。最后给出了一个简单例子。     

一种从面向对象Z规约到代码的精化演算方法

COOZ(complete object-oriented Z)的优势在于精确描述大型程序的规约.COOZ本身的结构 不支持精化演算,这限制了COOZ的应用能力,使COOZ难以作为完整的方法应用于软件的开发. 将精化演算引入COOZ,弥补了COOZ在设计和实现阶段的不足,同时也消除了规约与实现之间在 结构和表示方法上的完全分离,使程序开发在一个完整的框架下平滑进行.该文提出了基于CO OZ和精化演算的软件开发模型,通过实例讨论了数据精化和操作精化问题.在精化演算实现技 术方面构造了一种数据精化算子,提出一     

基于程序窗口推理的精化演算

由于数据精化需要针对更大的程序块, 所以,它比一般的算法精化更加复杂.在精化演算中过程如何有效地进行数据精化是形式化 方法研究中的一个重要内容.该文介绍了相关的基本概念.在精化演算的基础上,构造了一种 数据精化算子,并提出一种基于数据精化演算和程序窗口推理的数据精化的方法.     

一种严格的软件开发方法框架

本文系统地提出一种严格的软件开发方法,它基于逐步精化和重用组合的程序设计思想,将基于图形的半形式化方法和基于逻辑和转换系统的形式化方法镶嵌为一体,使软件开发中的“创造”和“演算”得到合理的折衷．本文已初步实现了面向该方法的实现工具．     

精化演算支撑工具的分析

利用精化演算的方法开发软件,其过程由巨大数量的小步骤构成,由手工完成极其烦琐,也极容易出错。因此,利用机器辅助工具的支持是必要的。在分析现有的精化工具的基础上,我们提出了一个用于软件形式化开发的精化工具RT(RefinementTool),对精化工具进行了需求分析和功能分析。在精化工具的设计中,分析了精化工具的设计目标、总体结构、精化与证明的表示方法、用户界面和工具的扩充性等问题,通过对精化和证明的表示方法的分析,提出了一种精化与证明的表示相结合的方法。     

两次数据精化的形式化软件开发方法

提出了一种从数据精化、过程精化、再数据精化的两次数据精化的形式化软件开发方法。传统Z规约数据精化很复杂。该文先采用过程写出初始规范,对模式进行第一次数据精化,然后把它转换为Z模式,再进行过程精化。最后再数据精化到且标代码。以常见动态Web网页脚本语言PHP为例,阐述了该方法。并为此写了一套从过程到Z模式的转化规则,以及精化到PHP的精化规则。     

一种将设计模式用于程序精化演算的并行程序设计方法研究

并行程序设计是并行计算的难点之一。提出了一种将设计模式用于程序精化演算的并行程序设计方法。它通过在Z语言的Schema演算体系中扩充并行的概念和表示,使用设计模式,将问题求解和并行开发的知识进行形式化的定义与描述,通过扩充的Schema演算将其与模型规范进行复合,逐步精化得到抽象并行程序。通过实例对这一方法进行了详细的描述。     

一种从Z规约到并行程序的精化方法

提出了一种通过对设计模式进行精化,从Z规约开发并行程序的方法.该方法对Z语言进行了并行扩充,从Z功能规约出发,通过使用扩展的设计模式逐步精化得到并行的设计规约,再通过保持语义的转换,得到可最后转换为并行代码的抽象并行程序.通过实例对这一方法进行了详细的描述.     

B语言和方法与Z、VDM的比较

1 引言形式化方法是建立在严格数学基础上的软件开发方法。软件开发的全过程中,从需求分析、规格说明、设计、编程、系统集成、测试、文档生成直至维护各阶段,凡是采用严格的数学语言、具有精确的数学语义的方法都称为形式化方法。形式化方法的一个重要研究内容是形式规格说明,即用具有精确语义的形式化语言书写的程序功能描述,它是论证程序是否正确的依据。形式化方法需要形式规格说明语言的支持,也可以说形式化方法的关键在于形式规格说明语言。形式规格说明语言提供了一个称为语法域的记号系统和一个称为语义域的目标集合,以及一组精确地定义哪些目标系统满足哪个规格说明的规则。根据对目标软件系统进行说明的方式分三种规格说明语言:     

精化演算支撑工具PRT的研究

1 引言精化演算是一种数学表示法和若干规则的集合,用于从程序规约推导出命令式程序。精化是从抽象程序向具体程序转换的过程,其中包含程序的正确性证明。精化的程序开发方法比对已有程序进行验证以保证程序正确性的方法更有效。通过精化演算中的转换规则可以演算出精化的程序。利用精化演算从规约导出程序的过程由大量步骤构成,非常适合利用机器工具进行辅助。本文对精化工具进行了需求分析和功能分析,研究了一个新的精化工具PRT(Program Refinement Tool)并与现有的一些工具进行了比较。     

The Least Conjunctive Refinement and Promotion in the Refinement Calculus

A syntactic calculation of Morgan's least conjunctive refinement operator for predicate transformers is developed. The operator is used to develop a general approach to lifting relational operators to predicate transformer operators. Predicate transformer versions of the relational conjunction and disjunction operators are considered in detail. The Z-based technique of program promotion is considered in a refinement calculus setting. A standard Z promotion example is recast in the refinement calculus. Received August 1997 / Accepted in revised form January 1999     

A Program Refinement Tool

The refinement calculus for the development of programs from specifications is well suited to mechanised support. We review the requirements for tool support of refinement as gleaned from our experience with existing refinement tools, and report on the design and implementation of a new tool to support refinement based on these requirements. The main features of the new tool are close integration of refinement and proof in a single tool (the same mechanism is used for both), good management of the refinement context, an extensible theory base that allows the tool to be adapted to new application domains, and a flexible user interface. Received June 1997 / Accepted in revised form June 1998     

Real-time refinement in Manna and Pnueli's temporal logic

A refinement calculus for the development of real-time systems is presented. The calculus is based upon a wide-spectrum language called TAM (the Temporal Agent Model), within which both functional and timing properties can be expressed in either abstract or concrete terms. A specification oriented semantics is given for the language. Program development is considered as a refinement process i.e. thecalculation of a structured program from an unstructured specification. An example program is developed.     

规格说明语言Z的类型检查

软件规格说明的正确性是软件目标代码正确性的前提。正确性要求这一就是类型正确。本文介绍Ｚ规格说明类型的检查器的实现方法,并对类型检查的环境、一致化方法、替换策略和类型变量的应用等问题进行讨论。     

A Logic for Schema-Based Program Development

We show how a theory of specification refinement and program development can be constructed as a conservative extension of our existing logic for Z. The resulting system can be set up as a development method for a Z-like specification language, or as a generalisation of a refinement calculus (with a novel semantics). In addition to the technical development we illustrate how the theory can be used in practice.     

Unifying proof methodologies of duration calculus and timed linear temporal logic

Linear temporal logic (LTL) has been widely used for specification and verification of reactive systems. Its standard model is sequences of states (or state transitions), and formulas describe sequencing of state transitions. When LTL is used to model real-time systems, a state is extended with a time stamp to record when a state transition takes place. Duration calculus (DC) is another well studied approach for real-time systems development. DC models behaviours of a system by functions from the domain of reals representing time to the system states. This paper extends this time domain to the Cartesian product of the real and the natural numbers. With the extended time domain, we provide the chop modality with a non-overlapping interpretation. This allows some linear temporal operators explicitly dealing with the discrete dimension of time to be derivable from the chop modality in essentially the same way that their continuous-time counterparts are in the classical DC. This provides a nice embedding of some timed LTL (TLTL) modalities into DC to unify the methods from DC and LTL for real-time systems development: Requirements and high level design decisions are interval properties and are therefore specified and reasoned about in DC, while properties of an implementation, as well as the refinement relation between two implementations, are specified and verified compositionally and inductively in LTL. Implementation properties are related to requirement and design properties by rules for lifting LTL formulas to DC formulas.On leave from the Department of Mathematics Computer Science the University of Leicester England.Received June 1999Accepted in revised form September 2003 by M. R. Hansen and C. B. Jones     

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.