语言的抽象、封装与变换型开发方法

该文提出了一种系统的软件开发方法——面向模型的变换型软件开发方法.这种方法把数据抽象的思想提高到语言抽象层次;把一类专用软件的规范抽象为语言的规范;把这类软件的实现抽象为语言的归约变换;用“规范+变换”抽象软件开发过程.为支持这种方法,提出了语言的一种抽象与封装机制Garment,以此定义语言中各成分的语法和语义,描述语言间的继承、屏蔽和扩充关系.最后,以语言知识库为核心,简要介绍了支持用Garment进行变换型开发的系统结构和工作流程.     

Information Modeling Aspects of Software Development

The distinction between the modeling of information and the modeling of data in the creation of automated systems has historically been important because the development tools available to programmers have been wedded to machine oriented data types and processes. However, advances in software engineering, particularly the move toward data abstraction in software design, allow activities reasonably described as information modeling to be performed in the software creation process. An examination of the evolution of programming languages and development of general programming paradigms, including object-oriented design and implementation, suggests that while data modeling will necessarily continue to be a programmer's concern, more and more of the programming process itself is coming to be characterized by information modeling activities.     

The Method of Levels of Abstraction

The use of “levels of abstraction” in philosophical analysis (levelism) has recently come under attack. In this paper, I argue that a refined version of epistemological levelism should be retained as a fundamental method, called the method of levels of abstraction. After a brief introduction, in section “Some Definitions and Preliminary Examples” the nature and applicability of the epistemological method of levels of abstraction is clarified. In section “A Classic Application of the Method of Abstraction”, the philosophical fruitfulness of the new method is shown by using Kant’s classic discussion of the “antinomies of pure reason” as an example. In section “The Philosophy of the Method of Abstraction”, the method is further specified and supported by distinguishing it from three other forms of “levelism”: (i) levels of organisation; (ii) levels of explanation and (iii) conceptual schemes. In that context, the problems of relativism and antirealism are also briefly addressed. The conclusion discusses some of the work that lies ahead, two potential limitations of the method and some results that have already been obtained by applying the method to some long-standing philosophical problems.

容器造型的模仿与概括之设计

大自然是艺术创作的源泉,我们模仿和概括抽象出自然中的美的形象和要素,使设计更具自然性、生动性、与趣味性,更贴近生活和更富有感染力。     

Expert-novice knowledge of computer programming at different levels of abstraction

Computer programming knowledge can be classified into five levels of abstraction: objective, conceptual, functional, logical, and physical. An experiment was carried out to determine whether the mastering of knowledge at different levels of abstraction changed with the level of skill. Ten experts and ten novices in C computer programming participated in the experiment. The subjects' knowledge at the five levels of abstraction was tested through 20 multiple-choice questions. The experimental results indicated that knowledge differences between experts and novices at an abstract level or a concrete level depended on what abstract or concrete knowledge was implied. Experts had better abstract knowledge than novices at the conceptual and functional levels but not at the objective level. Experts had better concrete knowledge than novices at the physical level but not at the logical level. The classification of computer programming knowledge in levels of abstraction and the experimental results helped in clarifying a general finding from previous studies that experts had better abstract knowledge than novices.     

多维空间角度方法提取植被覆盖区蚀变信息

基于光谱角制图法，提出运用多维空间角度方法来提取植被覆盖较好区域的遥感图像蚀变信息。采用目视解译方法得到的样本向量代替从波谱库中得到的端元组分矢量来计算多维向量间的空间角，并且加入合适的约束条件，来改进多维空间角度方法。给出了植被覆盖区蚀变信息提取的实施方法与步骤。最后运用改进的多维空间角度方法提取实际区域的蚀变信息，并将它与用比值法和主成分分析法得到的结果作比较。表明改进的多维空间角度方法提取蚀变信息的效果比较理想，与该地区的地质图件更为一致，从而证实了该方法的有效性。     

一种基于抽象解释和通用单调数据流框架的值范围分析方法

安全而又精确的值范围分析对编译器优化至关重要．系统地提出了一个基于抽象解释和通用单调数据流框架的值范围分析框架，包括精确的定叉、分析和完整的正确性证明．与一般的值范围分析方法不同，该框架不仅包括抽象解释，还包括与之对应的具体解释，以及相应的正确性证明．     

DSM系统中共享存储抽象机制的实现

虽然ＤＳＭ系统相互之间差异很大，但ＤＳＭ存在一个共同特征，即提供共享存储抽象机制。本文分析了ＤＳＭ系统共享存储抽象机制的实现，总结了各种不同的实现途径、实现细节及各自的优缺点，指出了ＤＳＭ发展的趋势及一些亟待解决的问题。     

多机并发系统中通信模型分层抽象的方法

针对多机并发系统的复杂性,为了辅助用户能从多个角度和层次全面地理解并发系统,就需要逆向产生出能够反映软件系统框架结构的高层架构。基于此本文以进程为边界,提出了一种分层抽取多机并发系统通信模型的方法。此方法基于反射和开放编译的植入机制来获取所需要的动态信息,在此基础上运用分层抽象的策略,分别从系统、节点、进程三个层次对多机并发系统的通信结构和设计结构进行逆向恢复,最后对该方法进行系统的实验研究。结果表明,分层抽象所得到并发系统的通信模型能够正确、有效地反映系统设计时的高层架构关系。     

嵌入式软件开发平台抽象层设计的一种思路

能否设计一个可屏蔽不同嵌入式RTOS差异的平台抽象层，对于软件产品能否迅速向新的RTOS平台移植、能否迅速提供多平台的支持，以较低成本快速应对技术的改进和市场的变化等方面都非常关键。平台抽象层设计的原理及设计过程中需要考虑的因素是讨论的主题。     

Signatures: A language extension for improving type abstraction and subtype polymorphism in C++

C++ uses inheritance as a substitute for subtype polymorphism. We give examples where this makes the type system too inflexible. We then describe a conservative language extension that allows a programmer to define an abstract type hierarchy independent of any implementation hierarchies, to retroactively abstract over an implementation, and to decouple subtyping from inheritance. This extension gives the user more of the flexibility of dynamic typing while retaining the efficiency and security of static typing. With default implementations and views flexible mechanisms are provided for implementing an abstract type by different concrete class types. We first show how the language extension can be implemented in a preprocessor to a C++ compiler, and then detail and analyse the efficiency of an implementation we directly incorporated in the GNU C++ compiler.     

Why zombies cannot write significant source code: The Knowledge Game and the art of computer programming

This article analyses the knowledge needed to understand a computer program within the philosophy of information. L. Floridi's method of levels of abstraction is applied to the relation between an ideal programmer and a modern computer seen together as an informational organism. The results obtained by the mental experiment known as the Knowledge Game are applied to this relation, so to explain what a programmer should know in order to program a modern computer. In particular, this analysis clearly shows why non-conscious agents have no hopes to write significant programs. Two main objections are then presented and attacked by corresponding counterobjections.     

A function-centered framework for reasoning about system failure at multiple levels of abstraction

This paper presents the knowledge organization for a simulation subsystem that is a component of a comprehensive expert system for failure modes and effects analysis. Organizing the simulation subsystem's knowledge base around a function-centered ontology produces an architecture that facilitates reasoning about an engineering design at multiple levels of abstraction and throughout the life-cycle of the design. Moreover, the resulting architecture provides the capability for incorporating computer-aided analysis and design tools early on into the conceptual design of an engineering system before a commitment is made to a specific technology to implement the system's behavior. The result is an expert system simulation knowledge source that can be used to reason about the effects of system failures based on conceptual designs, i.e. designs in which commitments to an underlying technology to achieve the system's function have not yet been made but computer-aided assistance for reasoning about the system's potential failure modes and effects is useful.     

Industry evaluation of the Requirements Abstraction Model

Software requirements are often formulated on different levels and hence they are difficult to compare to each other. To address this issue, a model that allows for placing requirements on different levels has been developed. The model supports both abstraction and refinement of requirements, and hence requirements can both be compared with each other and to product strategies. Comparison between requirements will allow for prioritization of requirements, which in many cases is impossible if the requirements are described on different abstraction levels. Comparison to product strategies will enable early and systematic acceptance or dismissal of requirements, minimizing the risk for overloading. This paper presents an industrial evaluation of the model. It has been evaluated in two different companies, and the experiences and findings are presented. It is concluded that the requirements abstraction model provides helpful improvements to the industrial requirements engineering process.

Understanding the Philosophical Underpinnings of Software Engineering Research in Information Systems

The Information Systems (IS) discipline, and related research, focuses on the development, understanding, and use of technology to meet business needs. Technology, in particular software, is the basis for IS research, making software engineering a critical component of research in the IS domain. While the importance of software development is well accepted, what constitutes high quality software engineering research is not well defined. Perhaps this is because some software development clearly is not research and it is hard to distinguish between pure application development, and systems development that pushes the boundaries of knowledge. Sir Karl Popper argued that the scientific quality of research is not based on its empirical method, but on the nature of the questions asked. Our research suggests that software engineering can meet Popper's criteria for scientific research.Drawing on well-established research philosophies, we propose a software engineering research methodology (SERM) and discuss the utility of this methodology for contributing to and expanding the IS body of knowledge. We also describe the considerations that need to be addressed by SERM to enhance acceptability of software engineering research in IS. Our suggestions are corroborated with a review of current IS software engineering research reported in leading IS journals.     

Levels of abstraction,emergentism and artificial life

I diagnose the current debate between epistemological and ontological emergentism as a Kantian antinomy, which has reasonable but irreconcilable thesis and antithesis. Kantian antinomies have recently returned to contemporary philosophy in part through the work of Luciano Floridi, and the method of levels of abstraction. I use a thought experiment concerning a computer simulation to show how to resolve the epistemological/ontological antinomy about emergence. I also use emergentism and simulations in artificial life to illuminate both levels of abstraction and theoretical challenge for building intelligent agents.     

一种重构二进制代码中类型抽象的方法

重构二进制代码中的类型信息对逆向工程、漏洞分析及恶意代码检测等方面具有重大的意义,由于类型信息在编译过程中被移除,且二进制代码中的低级抽象难以理解,因此类型重构一直被认为是恢复高级抽象遇到的困难问题之一,现有的大多工具对类型重构的准确度不够高.提出一种保守的类型重构方法,针对类型重构引入一种简单的中间语言,基于这种中间语言构造寄存器抽象语法树,并使用寄存器抽象语法树部分解决了基址指针别名问题,可有效收集基本类型和结构体类型的类型约束信息.提出一种判断二进制代码中的循环结构及识别循环变量的方法,可有效收集数组类型的约束信息,并据此生成类型约束,然后通过处理类型约束来重构最终的类型.使用CoreUtils中的15个程序作为测试用例,将该方法与IDA Pro进行对比实验.实验结果表明提出的方法不仅可以高效地重构数据类型,而且在结构体类型重构方面可恢复比IDA Pro多达5倍的数据.对这些数据的人工验证与分析表明,使用该方法重构的类型准确率高.     

Institutions of Variable Truth Values:An Approach in the Ordered Style

The concept of institution of variable truth values is introduced and some main results about institutions are generalized.In particular,some properties of institutions of variable truth values preserved by change of truth values are established.     

抽象数据类型概念多角度理解的教学探索

该文针对数据结构课程中抽象数据类型概念这一教学难点,分析抽象数据类型概念引入的原因,并从数学角度、程序设计角度以及面向对象的角度深刻理解这一概念,为学生把握数据结构课程内容的整体安排以及后续课程的铺垫奠定了坚实的基础。