Showing papers in "ACM Computing Surveys in 1985"

On understanding types, data abstraction, and polymorphism

Abstract: Our objective is to understand the notion of type in programming languages, present a model of typed, polymorphic programming languages that reflects recent research in type theory, and examine the relevance of recent research to the design of practical programming languages.Object-oriented languages provide both a framework and a motivation for exploring the interaction among the concepts of type, data abstraction, and polymorphism, since they extend the notion of type to data abstraction and since type inheritance is an important form of polymorphism. We develop a l-calculus-based model for type systems that allows us to explore these interactions in a simple setting, unencumbered by complexities of production programming languages.The evolution of languages from untyped universes to monomorphic and then polymorphic type systems is reviewed. Mechanisms for polymorphism such as overloading, coercion, subtyping, and parameterization are examined. A unifying framework for polymorphic type systems is developed in terms of the typed l-calculus augmented to include binding of types by quantification as well as binding of values by abstraction.The typed l-calculus is augmented by universal quantification to model generic functions with type parameters, existential quantification and packaging (information hiding) to model abstract data types, and bounded quantification to model subtypes and type inheritance. In this way we obtain a simple and precise characterization of a powerful type system that includes abstract data types, parametric polymorphism, and multiple inheritance in a single consistent framework. The mechanisms for type checking for the augmented l-calculus are discussed.The augmented typed l-calculus is used as a programming language for a variety of illustrative examples. We christen this language Fun because fun instead of l is the functional abstraction keyword and because it is pleasant to deal with.Fun is mathematically simple and can serve as a basis for the design and implementation of real programming languages with type facilities that are more powerful and expressive than those of existing programming languages. In particular, it provides a basis for the design of strongly typed object-oriented languages.

Three-dimensional object recognition

Abstract: A general-purpose computer vision system must be capable of recognizing three-dimensional (3-D) objects. This paper proposes a precise definition of the 3-D object recognition problem, discusses basic concepts associated with this problem, and reviews the relevant literature. Because range images (or depth maps) are often used as sensor input instead of intensity images, techniques for obtaining, processing, and characterizing range data are also surveyed.

Consistency in a partitioned network: a survey

Abstract: Recently, several strategies have been proposed for transaction processing in partitioned distributed database systems with replicated data. These strategies are surveyed in light of the competing goals of maintaining correctness and achieving high availability. Extensions and combinations are then discussed, and guidelines are presented for selecting strategies for particular applications.

Access methods for text

Abstract: This paper compares text retrieval methods intended for office systems. The operational requirements of the office environment are discussed, and retrieval methods from database systems and from information retrieval systems are examined. We classify these methods and examine the most interesting representatives of each class. Attempts to speed up retrieval with special purpose hardware are also presented, and issues such as approximate string matching and compression are discussed. A qualitative comparison of the examined methods is presented. The signature file method is discussed in more detail.

Self-organizing linear search

Abstract: Algorithms that modify the order of linear search lists are surveyed. First the problem, including assumptions and restrictions, is defined. Next a summary of analysis techniques and measurements that apply to these algorithms is given. The main portion of the survey presents algorithms in the literature with absolute analyses when available. The following section gives relative measures that are applied between two or more algorithms. The final section presents open questions.

A framework for choosing a database query language

Abstract: This paper presents a systematic approach to matching categories of query language interfaces with the requirements of certain user types. The method is based on a trend model of query language development on the dimensions of functional capabilities and usability. From the trend model the following are derived: a classification scheme for query languages, a criterion hierarchy for query language evaluation, a comprehensive classification scheme of query language users and their requirements, and preliminary recommendations for allocating language classes to user types.The method integrates the results of existing human factors studies and provides a structured framework for future research in this area. Current and expected developments are exemplified by the description of "new generation" database query languages. In a practical query language selection problem, the results of this paper can be used for preselecting suitable query language types; the final selection decision will also depend on organization-specific factors, such as the available database management system, hardware and software strategies, and financial system costs.

Research in music and artificial intelligence

Abstract: Although the boundaries of artificial intelligence (AI) remain elusive, computers can now perform musical tasks that were formerly associated exclusively with naturally intelligent musicians. After a historical note, this paper sermonizes on the need for AI techniques in four areas of musical research: composition, performance, music theory, and digital sound processing. The next part surveys recent work involving AI and music. The discussion concentrates on applications in the four areas of research just mentioned. The final part examines how AI techniques of planning and learning could be used to expand the knowledge base and enrich the behavior of musically intelligent systems.

4.2BSD and 4.3BSD as examples of the UNIX system

Abstract: This paper presents an in-depth examination of the 4.2 Berkeley Software Distribution, Virtual VAX-11 Version (4.2BSD), which is a version of the UNIX Time-Sharing System. There are notes throughout on 4.3BSD, the forthcoming system from the University of California at Berkeley. We trace the historical development of the UNIX system from its conception in 1969 until today, and describe the design principles that have guided this development. We then present the internal data structures and algorithms used by the kernel to support the user interface. In particular, we describe process management, memory management, the file system, the I/O system, and communications. These are treated in as much detail as the UNIX licenses will allow. We conclude with a brief description of the user interface and a set of bibliographic notes.

A review of recent developments in solving ODEs

Abstract: Mathematical models when simulating the behavior of physical, chemical, and biological systems often include one or more ordinary differential equations (ODEs). To study the system behavior predicted by a model, these equations are usually solved numerically.Although many of the current methods for solving ODEs were developed around the turn of the century, the past 15 years or so has been a period of intensive research. The emphasis of this survey is on the methods and techniques used in software for solving ODEs.ODEs can be classified as stiff or nonstiff, and may be stiff for some parts of an interval and nonstiff for others. We discuss stiff equations, why they are difficult to solve, and methods and software for solving both nonstiff and stiff equations. We conclude this review by looking at techniques for dealing with special problems that may arise in some ODEs, for example, discontinuities.Although important theoretical developments have also taken place, we report only those developments which have directly affected the software and provide a review of this research. We present the basic concepts involved but assume that the reader has some background in numerical computing, such as a first course in numerical methods.

Programming languages for computer music synthesis, performance, and composition

Abstract: The development of formal, descriptive, and procedural notations has become a practical concern within the field of music now that computers are being applied to musical tasks. Music combines the real-time demands of performance with the intellectual demands of highly developed symbolic systems that are quite different from natural language. The richness and variety of these demands makes the programming language paradigm a natural one in the musical application of computers. This paradigm provides musicians with a fresh perspective on their work. At the same time, music is a very advanced form of human endeavor, making computer music applications a worthy challenge for computer scientists. In this paper we outline the traditional tasks and forms of representation in music, then proceed with a survey of languages that deal with music programming.

Computer-music interfaces: a survey

Abstract: This paper is a study of the unique problems posed by the use of computers by composers and performers of music. The paper begins with a presentation of the basic concepts involved in the musical interaction with computer devices, followed by a detailed discussion of three musical tasks: music manuscript preparation, music language interfaces for composition, and real-time performance interaction. Fundamental design principles are exposed through an examination of several early computer music systems, especially the Structured Sound Synthesis Project. A survey of numerous systems, based on the following categories, is presented: compositions and synthesis languages, graphics score editing, performance instruments, digital audio processing tools, and computer-aided instruction in music systems. An extensive reference list is provided for further study in the field.

System architectures for computer music

Abstract: Computer music is a relatively new field While a large proportion of the public is aware of computer music in one form or another, there seems to be a need for a better understanding of its capabilities and limitations in terms of synthesis, performance, and recording hardware This article addresses that need by surveying and discussing the architecture of existing computer music systemsSystem requirements vary according to what the system will be used for Common uses for computer music systems include composition, performance, research, home entertainment, and studio recording/mixing This paper outlines system components with this wide diversity of possible uses in mindCurrent synthesis and analysis techniques, and the different way in which these techniques can be implemented in special-purpose hardware, are comprehensively reviewed Design specifications are given for certain digital-to-analog (and analog-to-digital) converters, disk interfaces, system organization, control hardware and software, and numerical precisionSeveral synthesis systems are described in detail, with an emphasis on theoretical developments and innovative design Commercial synthesizers and other architectures are also briefly mentioned