Proceedings

This paper presents a constructive model for data which suggests some precise definitions of notions like type, name, constants, declarations etc. The model is based on an old idea of looking at data as a mapping from a set of names to a set of values. ...

If a program is structured using abstract data types as the basic unit of modularity, then that program is much easier to extend or modify. This thesis is illustrated by the staged development of a program to compute prime numbers based on the sieve of ...

The System for Business Automation (SBA) is a system within which application experts—non-programmers—can describe and execute their applications on a computer. This paper describes the programming language part of the system. This language is a ...

This paper describes EQUEL, a programming language which embeds the relational data sublanguage QUEL into the general purpose programming language “C”. Both QUEL and EQUEL are operational parts of the INGRES relational data base management system at ...

The concept of an abstract data type is available in the Model programming language as a proposed improvement to current ideas of programming methodology. In structured programming the principal technique is refinement of procedures. In Model, the ...

A relational data base is herein defined as a collection of normalized relations (relations in first normal form) and a collection of domains. A normalized relation may be viewed as a table, wherein each row of the table corresponds to a tuple of the ...

The concept of abstract data types has emerged from programming language research as a device to encourage and facilitate structured and modular programming [1]. It separates the abstraction of a data object from its implementation. The user of an ...

It is currently popular to say that programming languages need “data abstraction facilities,” and to assert that the provision of such facilities would provide conceptual and practical advantages in the domain of data structures akin to the advantages ...

I have now written, have available from SofTech, and have submitted for publication elsewhere, the first two of a series of deep philosophical papers [1, 2] about Plex [3]. Among other things, I believe these papers begin to provide a proper foundation ...

A number of interesting research problems arise from current attempts to incorporate abstraction mechanisms in programming languages. Some of them are central issues in current research projects and others are direct extensions of current work. Several ...

An abstraction provides a statement of the properties of a data type without any commitment to a specific implementation. Programs which use abstractions can be developed and verified without regard to how the abstraction will be realized. Any type ...

Real-world systems modelled by data bases are often quite complex. It is essential that the data base be structured in a way which supports a users abstractions about the real-world system. The “relation” data type is introduced as a structuring ...

Abstract data types can play a significant role in the development of software that is reliable, efficient, and flexible. This paper presents and discusses the application of an algebraic technique for the specification of abstract data types. Among the ...

The problem of determining, analysis and description of a particular application's information structure (and relations) and the process of mapping the information structure to a “good” data structure (in this case a DBTG-type structure) is considered. ...

Extended set theory is an effective method for describing the complex data structures needed to support large-scale data base applications. This paper describes the incorporation of the salient concepts of extended set theory into a general tool for the ...

The presence of pointer variables in high level programming languages constitutes an artifact originally introduced to support the representation of recursive data structures. Programming practice has come to rely on pointer variables for their ...

The traditional file structures used to support fast response to complex user queries have been based on the inverted list organization, using either the pointer or bit string representation. In this paper, the use of bit maps for executing multiple key ...

At present, there is considerable debate whether, in light of what is being learned about construction of reliable software, pointers are desirable in high level programming languages. One side [Hoa73, Hoa75] maintains that

1) Pointers are like the goto ...

We explore some new and old ideas concerning data types; what a data type is, overloading operators, when and how implicit conversions between programmer data types should be allowed and so forth. The current notion that a data type is a set of values ...

The notion of dividing complex problems into hierarchic levels of abstraction has a long history. Recently this approach under the name, structured programming, has been used in a pragmatic way to simplify the structure of procedural programs. The ...

Data types are an important design tool because they allow freedom of abstraction. Thus, they are useful for constructing large software systems, including operating systems. It is shown that when dealing with problems of concurrency, the use of path ...

The concept of “type” has been used without a precise definition in discussions about programming languages for 20 years. Before the concept of user defined data types was introduced, a definition was not necessary for discussions of specific ...

In this paper we assert that the hierarchical view of data will continue to be popular for a broad class of applications and users. In particular, some of these applications require complex data manipulation which, heretofore, has been dealt with ...

A data type encapsulation scheme in which the “space” operations are expressed naturally in terms of the base language operators is described. The scheme results from a conceptual separation of operators and procedure calls in the base language and ...

In this paper it is argued that there is a strong connection between the issue of abstract types and the more general issue of information hiding in large program systems, since abstraction has to be enforced by the careful and controlled hiding of ...