Pointers and data abstractions in high level languages—II: Correctness proofs

Recognizing the problems that the use of pointers pose to the construction of reliable software, this two-part paper proposes a scheme by which pointers may be used in a controlled manner to build data abstractions without being used as abstractions in their own right. Part I, published in Computer Languages 2, 135–148, presents the language constructs facilitating the proposal. Part II, in this Issue, attempts to show, by use of a fairly complex example, that proving the correctness of an implementation of an abstraction built in this manner from pointers need not be more difficult than other implementation correctness proofs.     

The application of statistical process control in U.K. automotive manufacture: Some research findings

This paper reports on the findings of a questionnaire survey into the use of statistical process control (SPC) in a sample of United Kingdom automotive suppliers. All the 76 respondents had attended the Ford-approved three-day course on SPC held at the University of Manchester Institute of Science and Technology (UMIST). The survey investigated the following broad issues of SPC: motivation, implementation, application, suppliers and customers, and benefits. A number of findings surprised the authors; these included the number of organizations who had not appointed a SPC facilitator, organizations experiencing difficulties in deciding what type of control charts to use, control charts being ‘filled-in’ by people not directly responsible for control of a process, charts being displayed away from work areas and the frankness of some suppliers in declaring that the vast majority of their manufacturing processes are not in a state of statistical control. If there is an overall message arising from the findings it is that the introduction and application of SPC should not be overcomplicated.     

TMS: A free-form text-management system

TMS (Text Management System) is a database management system that supports an access method based on both select and search queries. TMS provides support for variable-length records with pointer fields within the relation. Pointers can be used to support not only text but data from any media, such as graphics and images. An inverted index based on the variable-length record structure is used for speedy retrieval of records based on keywords. In this paper, the variable length record management of TMS and the keyword-based retrieval mechanism are described.     

UNIX内存管理的研究和分析

该文对UNIX系统V内存管理进行了较为深入的探讨,阐明了虚存、实存、系统空间、进程空间、页表等的概念及它们之间的内在关系;研究分析了内存管理中的分页系统的优缺点,并提出了一个改进的双表针时钟算法。     

Frame rule for mutually recursive procedures manipulating pointers

Using a predicate transformer semantics of programs, we introduce statements for heap operations and separation logic operators for specifying programs that manipulate pointers. We prove a powerful Hoare total correctness rule for mutually recursive procedures manipulating pointers. The rule combines earlier proof rules for (mutually) recursive procedures with the frame rule for pointer programs. The theory, including the proofs, is implemented in the theorem prover PVS. In this implementation program variables and addresses can store values of almost any type of the theorem prover.     

Pointers and data abstractions in high level languages—I: Language proposals

Recognizing the problems that the use of pointers pose to the construction of reliable software, this two-part paper proposes a scheme by which pointers may be used in a controlled manner to build data abstractions without being used as abstractions in their own right. Part I presents the language constructs facilitating the proposal. Part II (to be published in a forth-coming issue) attempts to show, by use of a fairly complex example, that proving the correctness of an implementation of an abstraction built in this manner from pointers need not be more difficult than other implementation correctness proofs.