Showing papers in "Communications of The ACM in 1983"
TL;DR: In this paper, an interval-based temporal logic is introduced, together with a computationally effective reasoning algorithm based on constraint propagation, which is notable in offering a delicate balance between time and space.
Abstract: An interval-based temporal logic is introduced, together with a computationally effective reasoning algorithm based on constraint propagation. This system is notable in offering a delicate balance between
7,362 citations
TL;DR: Because of the extraordinary clarity and importance of the Commission's Report, the editors of the Communica t ions decided to reprint the Report's main section in its entirety and present it to you here.
Abstract: released a remarkab le report, A Nation at Risk. This Report has s t imulated in the media considerable discussion about the problems in our schools, speculation about the causes, and ass ignment of blame. Astonishingly, f e w of the media reports have focused on the specific f indings and recommendat ions of the Commission. A lmos t none of the med ia reports tells that the Commission i tsel f re frained f rom speculation on causes and f rom assignment of blame. Because of the extraordinary clarity and importance of the Commission's Report, the editors of the Communica t ions decided to reprint the Report's main section in its entirety. We are p leased to present it to you here.
5,832 citations
TL;DR: In this paper, a survey of production managers is used to provide additional support for the instrument, eliminate scales that are psychometrically unsound, and develop a standard short form for use when only an overall assessment of information satisfaction is required and survey time is limited.
Abstract: This paper critically reviews measures of user information satisfaction and selects one for replication and extension. A survey of production managers is used to provide additional support for the instrument, eliminate scales that are psychometrically unsound, and develop a standard short form for use when only an overall assessment of information satisfaction is required and survey time is limited.
1,607 citations
TL;DR: A new, extended Boolean information retrieval system is introduced which is intermediate between the Boolean system of query processing and the vector processing model, and Laboratory tests indicate that the extended system produces better retrieval output than either the Boolean or thevector processing systems.
Abstract: In conventional information retrieval Boolean combinations of index terms are used to formulate the users'' information requests. While any document is in principle retrievable by a Boolean query, the amount of output obtainable by Boolean processing is difficult to control, and the retrieved items are not ranked in any presumed order of importance to the user population. In the vector processing model of retrieval, the retrieved items are easily ranked in decreasing order of the query-record similarity, but the queries themselves are unstructured and expressed as simple sets of weighted index terms. A new, extended Boolean information retrieval system is introduced which is intermediate between the Boolean system of query processing and the vector processing model. The query structure inherent in the Boolean system is preserved, while at the same time weighted terms may be incorporated into both queries and stored documents; the retrieved output can also be ranked in strict similarity order with the user queries. A conventional retrieval system can be modified to make use of the extended system. Laboratory tests indicate that the extended system produces better retrieval output than either the Boolean or the vector processing systems.
909 citations
TL;DR: In this paper, the authors present a real-time garbage collection algorithm that makes storage for short-lived objects cheaper than storage for longlived objects, and operates in real time.
Abstract: In previous heap storage systems, the cost of creating objects and garbage collection is independent of the lifetime of the object. Since objects with short lifetimes account for a large portion of storage use, it is worth optimizing a garbage collector to reclaim storage for these objects more quickly. The garbage collector should spend proportionately less effort reclaiming objects with longer lifetimes. We present a garbage collection algorithm that (1) makes storage for short-lived objects cheaper than storage for long-lived objects, (2) that operates in real time—object creation and access times are bounded, (3) increases locality of reference, for better virtual memory performance, (4) works well with multiple processors and a large address space.
651 citations
TL;DR: In this article, the authors classified end users into six distinct types, each of which needs differentiated education, support, and control from the Information Systems (I/S) function, and paid close attention to the need to involve functional support personnel in the I/S end user management process.
Abstract: End users can be classified into six distinct types. Each of them needs differentiated education, support, and control from the Information Systems function. To support a large number of their applications a new computing environment, “the third environment” must be developed by Information Systems (I/S) management. Close attention must also be paid by I/S management to the need to involve “functional support personnel” (end users in each functional area who spend most of their time programming and aiding other end users) in the I/S end user management process.
540 citations
TL;DR: This paper demonstrates some of principles of system design principles through the analysis of one class of errors: slips of action, defined to be situations in which the user's intention was proper, but the results did not conform to that intention.
Abstract: By analyzing the classes of errors that people make with systems, it is possible to develop principles of system design that minimize both the occurrence of error and the effects. This paper demonstrates some of these principles through the analysis of one class of errors: slips of action. Slips are defined to be situations in which the user's intention was proper, but the results did not conform to that intention. Many properties of existing systems are conducive to slips; from the classification of these errors, some procedures to minimize the occurrence of slips are developed.
427 citations
TL;DR: The KWIC index would be Abstract Data Types and Software Validation on the Criteria to be Used in Decomposing Systems into Modules Abstract Data types and software Validation.
Abstract: Data Types and Software Validation On the Criteria to be Used in Decomposing Systems into Modules On the Design and Development of Program Families A Design Methodology for Reliable Software Systems the KWIC index would be Abstract Data Types and Software Validation On the Criteria to be Used in Decomposing Systems into Modules Abstract Data Types and Software Validation On the Criteria to be Used in Decomposing Systems into Modules On the Design and Development of Program Families On the Design and Development of Program Families On the Design and Development of Program Families A Design Methodology for Reliable Software Systems A Design Methodology for Reliable Software Systems On the Criteria to be Used in Decomposing Systems into Modules On the Design and Development of Program Families A Design Methodology for Reliable Software Systems A Design Methodology for Reliable Software Systems Abstract Data Types and Software Validation A Design Methodology for Reliable Software Systems On the Criteria to be Used in Decomposing Systems into Modules Abstract Data Types and Software ValidationData Types and Software Validation On the Criteria to be Used in Decomposing Systems into Modules Abstract Data Types and Software Validation On the Criteria to be Used in Decomposing Systems into Modules On the Design and Development of Program Families On the Design and Development of Program Families On the Design and Development of Program Families A Design Methodology for Reliable Software Systems A Design Methodology for Reliable Software Systems On the Criteria to be Used in Decomposing Systems into Modules On the Design and Development of Program Families A Design Methodology for Reliable Software Systems A Design Methodology for Reliable Software Systems Abstract Data Types and Software Validation A Design Methodology for Reliable Software Systems On the Criteria to be Used in Decomposing Systems into Modules Abstract Data Types and Software Validation Assume a program that takes a list of titles and produces a KWlC index. An informal solution is: 1. Consider each title in the title list in turn. 2. For each title, consider each word in that title. 3. If the word is not a common word, enter the title into the KWIC index at the position identified by that and perhaps subsequent words. lO.1. The Data Types The common nouns are: TITLE, TITLE_LIST, WORD, COMMON_WORD, KWIC_INDEX, POSITION, THAT_AND_SUBSEQUENT_WORDS Notice that we have listed THAT_AND_SUBSEQUENT_ WORDS as a data type. This is certainly not one of the more obvious types and it was discovered only after a fair amount of analysis. This is an \"ugly\" data type, but it does characterize, on the level of the problem, the information required to determine where a title fits in a KWIC Index with respect to a given word in the title• We can define the initial data types as: type TrrLE is type TITLE_LIST is type WORD is type COMMON_WORD is type KWIC_INDEX is type POSITION is type THAT_AND_SUBSEQUENT_WORDS is ° ° ~ 10.2. The Objects The objects are: THE_TITLE_LIST; EACH_TITLE, THAT_TITLE, THE_TITLE; (These are used synonymously.) EACH_WORD, THE_WORD, THE_CURRENT_WORD; (These are used synonymously.) THE_KWIC_INDEX; THE_POSITION. So we can make our initial object declarations: THE_TITLE_LIST TITLE_LIST; THE_TITLE TITLE; THE_WORD WORD; THE_KWIC_INDEX KWIC_INDEX; THE_POSITION P o s m o N ; 10.3. The Operators The operators (in the form of Ada subprogram signatures) are: procedure CONSIDER_NEXT_TITLE (NEXT_TITLE : out TITLE; A TrI'LE_LIST : in out TITLE_LIST; MORE_TITLES : out BOOLEAN); Given a TITLE_LIST, sets NEXT_TITLE to the next unscanned TITLE and increments the TITLE_LIST's internal \"scan pointer.\" Sets MORE_TITLES depending on whether or not an unscanned title has been found in the LIST. procedure CONSIDER_FIRST_TITLE (FIRST_TITLE : out TITLE; A_TITLE_LIST : in out TITLE_LIST; ANY_TITLES : out BOOLEAN); Good practice suggests an initialization \"first\" operator to complement the \"next\" operator. The meanings of the parameters are similar• procedure CONSIDER_NEXT_WORD (NEXT_WORD : out WORD; A_TITLE : in out TITLE; MORE_WORDS : out BOOLEAN); Similar to the CONSIDER_NEXT_TITLE operator except that the object scanned is a single TITLE and the object scanned for is a WORD. In addition, titles have a \"current word\" indicator that is set to the NEXT_ WORD. . . 892 Communications of the ACM November 1983 Volume26 Number 11 procedure CONSIDER_FIRST_WORD (FIRST_WORD : o u t WORD; A_TITLE : in o u t TRIFLE; ANY_WORDS : o u t BOOLEAN); A \"first\" WORD operator to complement the \"next\" WORD operator. function IS_A_COMMON_WORD (A_WORD : WORD) return BOOLEAN; Determines whether the given WORD is a COMMON_WORD. procedure ENTER(A_TITLE : TITLE; A_KWIC_INDEX : KWlC_INDEX; A_POSITION : POSITION); Enters the TITLE into the KWIC_INDEX at the indicated position. function REMAINING_WORDS(A_TITLE : TITLE) return THAT_AND_SUBSEQUENT_WORDS; Returns the sequence of words remaining in the title from the \"current word\" (see CONSIDER_NEXT_ WORD) to the end of the title. In Ada, the name of a subprogram may not be the same as the name of a data type. function WHICH_POSITION (WORDS : THAT_AND_ SUBSEQUENT_WORDS; A_KWIC_INDEX : KWIC_INDEX) relurn POSITION; Finds the POSITION in the KWIC_INDEX where rifles are indexed under the \"current and perhaps subsequent word(s)\" in the given TITLE. 10.4 The Control Structure and the Final Solution The control structure is a simple pair of nested loops. They are shown clearly in the final program. The final program consists of two packages and a procedure that uses those packages. One package defines the data types and the operators for WORDs and TITLEs and the other defines the data types and operators for KWIC objects. package TITLES_AND_WORDS is Requirements Data types for dealing with rifles that consist of sequences of words. Conceptual Model The cleanest way to give the conceptual model is to make use of a previously defined, generic package for general sequences. Since generics are not discussed here, we do not give the complete specification. We do assume, though, that title sequences have pointers that may be set and moved. type THAT_AND_SUBSEQUENT_WORDS is private; type TITLE is private; type TITLE_LIST is private; type WORD is private; O p e r a t o r s We do not repeat the descriptions of the operators. They are the same as given earlier. procedure CONSIDER_FIRST_TITLE (FIRST_TITLE : o u t TRIFLE; A_TITLE_LIST : in o u t TITLE_LIST; ANY_TITLES : o u t BOOLEAN); procedure CONSIDER_NEXT_TITLE (NEXT_TITLE : o u t TITLE; A_TITLE_LIST : in o u t TITLE_LIST; MORE_TITLES : o u t BOOLEAN); procedure CONSIDER_FIRST_WORD (FIRST_WORD : o u t WORD; A_TITLE : in out TITLE; ANY_WORDS : o u t BOOLEAN); procedure CONSIDER_NEXT_WORD (NEXT_WORD : o u t WORD; A_TITLE : in out TITLE; MORE_WORDS : o u t BOOLEAN); function REMAINING_WORDS(A_TITLE : TITLE) r e t u r n THAT_AND_SUBSEQUENT_WORDS; e n d TITLES_AND_WORDS; with TITLES_AND_WORDS; use TITLES_AND_WORDS; package KWIC_STUFF is R e q u i r e m e n t s Data types for KWIC indices. C o n c e p t u a l M o d e l Again, no complete conceptual model is given since it too is best described in terms of a generic sequence package. type COMMON_WORD is private; type KWIC_INDEX is private; type POSITION is private; O p e r a t o r s Again, we do not repeat the operator descriptions. function IS_A_COMMON_WORD(A_WORD : WORD) r e t u r n BOOLEAN; procedure ENTER (A_T1TLE : TITLE: A_KWIC_INDEX : KWIC_INDEX; A_POSITION : POSITION); function WHICH_POSITION (WORDS : THAT_WORD_AND_ : SUBSEQUENT_WORDS; A_KWIC_INDEX : KWIC_INDEX) return POSITION;
347 citations
TL;DR: This research was partially supported by National Science Foundation Grant ECS-8023177 and may be adapted for use in teaching and research.
Abstract: This research was partially supported by National Science Foundation Grant ECS-8023177. Permission to copy without fee all or part of this material is granted provided that the copies are not made or distributed for direct commercial advantage, the ACM copyright notice and the title of the publication and its date appear, and notice is given that copying is by permission of the Association for Computing Machinery. To copy otherwise, or to republish, requires a fee and/or specific permission. © 1983 ACM 0001-0782/83/1100-0957 75¢
340 citations
TL;DR: This work was supported by the Army Research Institute for the Behavioral and Social Sciences and the National Science Foundation under NSF Grant SED-81-12403.
Abstract: Authors' Present Addresses: Elliot Soloway and Kate Ehrlich, Department of Computer Science, Yale University, P.O. Box 2158, New Haven, CT 06520; Jeffrey Bonar, Learning Research and Development Center, Univ. of Pittsburgh, Pittsburgh, PA 15260. This work was supported by the Army Research Institute for the Behavioral and Social Sciences. under ARI Grant No. MDA903-80-C-0508. This work was also supported by the National Science Foundation under NSF Grant SED-81-12403. Any opinions, findings, conclusions or recommendations expressed in this report are those of the authors, and do not necessarily reflect the views of the U.S. Government. Permission to copy without fee all or part of this material is granted provided that the copies are not made or distributed for direct commercial advantage, the ACM copyright notice and the title of the publication and its date appear, and notice is given that copying is by permission of the Association for Computing Machinery. To copy otherwise, or to republish, requires a fee and/or specific permission. © 1983 ACM 0001-0782/83/1100-0853 75¢ ELLIOT SOLOWA Y Yale University JEFFREY BONAR University of Massachusetts
330 citations
TL;DR: A static analysis algorithm is presented here that addresses the following problems: how processes are synchronized, what determines when programs are run in parallel, and how errors are detected in the synchronization structure.
Abstract: Developing and verifying concurrent programs presents several problems. A static analysis algorithm is presented here that addresses the following problems: how processes are synchronized, what determines when programs are run in parallel, and how errors are detected in the synchronization structure. Though the research focuses on Ada, the results can be applied to other concurrent programming languages such as CSP.
IBM1
TL;DR: The concepts behind the five principal normal forms in relational database theory are presented in simple terms as mentioned in this paper, and the concepts behind relational database normal forms can be found in Table 1...
Abstract: The concepts behind the five principal normal forms in relational database theory are presented in simple terms
TL;DR: A single formulation encompassing both stochastic and multidimensional optimal path problems is considered, in which a utility function defines preference among candidate paths, and the ability to state explicit conditions for exact solutions using standard methods and the applicability of well-understood approximation techniques is explored.
Abstract: This paper explores computationally tractable formulations of stochastic and multidimensional optimal path problems, each as an extension of the shortest path problem. A single formulation encompassing both problems is considered, in which a utility function defines preference among candidate paths. The result is the ability to state explicit conditions for exact solutions using standard methods, and the applicability of well-understood approximation techniques.
TL;DR: Examination of some behavioral, organizational, and social issues surrounding remote work, particularly work at home finds individuals who worked at home successfully were found to be highly self-motivated and self-disciplined and to have skills which provided them with bargaining power.
Abstract: Remote work refers to organizational work that is performed outside of the normal organizational confines of space and time. The term telecommuting refers to the substitution of communications capabilities for travel to a central work location. Office automation technology permits many office workers to be potential telecommuters in that their work can be performed remotely with computer and communications support. This paper examines some behavioral, organizational, and social issues surrounding remote work, particularly work at home.An exploratory study was conducted of 32 organizational employees who were working at home. Important characteristics of jobs that can be performed at home were: minimum physical requirements, individual control over work pace, defined deliverables, a need for concentration, and a relatively low need for communication. The individuals who worked at home successfully were found to be highly self-motivated and self-disciplined and to have skills which provided them with bargaining power. They also made the arrangement either because of family requirements or because they preferred few social contacts beyond family.
IBM1
TL;DR: Experiments suggest that some versions of a listening typewriter, even upon first using them, could be at least as good as traditional methods of handwriting and dictating.
Abstract: With a listening typewriter, what an author says would be automatically recognized and displayed in front of him or her. However, speech recognition is not yet advanced enough to provide people with a reliable listening typewriter. An aim of our experiments was to determine if an imperfect listening typewriter would be useful for composing letters. Participants dictated letters, either in isolated words or in consecutive word speech. They did this with simulations of listening typewriters that recognized either a limited vocabulary (1000 or 5000 words)or an unlimited vocabulary. Results suggest that some versions, even upon first using them, could be at least as good as traditional methods of handwriting and dictating. Isolated word speech with large vocabularies may provide the basis for a useful listening typewriter.
TL;DR: Path analysis supports the proposed causal model of turnover among computer specialists and suggest turnover indirectly through its influence on the other model variables.
Abstract: Four variables suggested by previous research were included in a proposed causal model of turnover among computer specialists. When tested using correlational analysis, three of the variables were significant inverse predictors of turnover. A fourth variable was also inversely related to turnover, but not significantly so. Path analysis supports the proposed causal model and suggest turnover indirectly through its influence on the other model variables.
TL;DR: This paper illustrates the specification of the user interface module for the family of message systems and surveys specification techniques that can be applied to human-computer interfaces and divides the techniques into two categories: those based on state transition diagrams and thosebased on BNF.
Abstract: Formal specification techniques are valuable in software development because they permit a designer to describe the external behavior of a system precisely without specifying its internal implementation. Although formal specifications have been applied to many areas of software systems, they have not been widely used for specifying user interfaces. In the Military Message System project at the Naval Research Laboratory, the user interfaces as well as the other components of a family of message systems are specified formally, and prototypes are then implemented from the specifications. This paper illustrates the specification of the user interface module for the family of message systems. It then surveys specification techniques that can be applied to human-computer interfaces and divides the techniques into two categories: those based on state transition diagrams and those based on BNF. Examples of both types of specifications are given. Specification notations based on state transition diagrams are preferable to those based on BNF because the former capture the surface structure of the user interface more perspicuously. In either notation, a high-level abstraction for describing the semantics of the user interface is needed, and an application-specific one is used here.
PARC1
TL;DR: The methodology has thus far been used to evaluate nine diverse text editors, producing an initial database of performance results that tells us not only about the editors but also about the users—the magnitude of individual differences and the factors affecting novice learning.
Abstract: This paper presents a methodology for evaluating text editors on several dimensions: the time it takes experts to perform basic editing tasks, the time experts spend making and correcting errors, the rate at which novices learn to perform basic editing tasks, and the functionality of editors over more complex tasks. Time, errors, and learning are measured experimentally; functionality is measured analytically; time is also calculated analytically. The methodology has thus far been used to evaluate nine diverse text editors, producing an initial database of performance results. The database is used to tell us not only about the editors but also about the users—the magnitude of individual differences and the factors affecting novice learning.
TL;DR: A multiprogramming system is described in which all activities are divided over a number of sequential processes, in each of which one or more independent abstractions have been implemented.
Abstract: A multiprogramming system is described in which all activities are divided over a number of sequential processes. These sequential processes are placed at various hierarchical levels, in each of which one or more independent abstractions have been implemented. The hierarchical structure proved to be vital for the verification of the logical soundness of the design and the correctness of its implementation.
TL;DR: This paper provides a set of guidelines for the design of software interfaces for video terminals that describes how to optimize screen layouts, interactive data entry, and error handling, as well as many practical techniques for improving man-machine interaction.
Abstract: This paper provides a set of guidelines for the design of software interfaces for video terminals. It describes how to optimize screen layouts, interactive data entry, and error handling, as well as many practical techniques for improving man-machine interaction. Emphasis is placed on factors relating to perceptual and cognitive psychology rather than on gross physiological concerns. Ways in which interfaces can be evaluated to improve their user friendliness are also suggested. The author summarizes many ideas that can be found in other, more comprehensive texts on the subject. These guidelines will provide practicing software designers with useful insights into some of today's principal terminal interface design considerations.
TL;DR: It is recommended that a moderate level of indentation be used to increase program comprehension and user satisfaction.
Abstract: The consensus in the programming community is that indentation aids program comprehension, although many studies do not back this up. We tested program comprehension on a Pascal program. Two styles of indentation were used--blocked and nonblocked--in addition to four passible levels of indentation (0, 2, 4, 6 spaces). Both experienced and novice subjects were used. Although the blocking style made no difference, the level of identation had a significant effect on program comprehension. (2--4 spaces had the highest mean score for program comprehension.) We recommend that a moderate level of indentation be used to increase program comprehension and user satisfaction.
TL;DR: The results show that beginning programmers—although able to perform adequately on mastery tests in program generation—possessed a wide range of misconceptions concerning the statements they had learned.
Abstract: In the process of learning a computer language, beginning programmers may develop mental models for the language. A mental model refers to the user's conception of the “invisible” information processing that occurs inside the computer between input and output. In this study, 30 undergraduate students learned BASIC through a self-paced, mastery manual and simultaneously had hands-on access to an Apple II computer. After instruction, the students were tested on their mental models for the execution of each of nine BASIC statements. The results show that beginning programmers—although able to perform adequately on mastery tests in program generation—possessed a wide range of misconceptions concerning the statements they had learned. This paper catalogs beginning programmers' conceptions of “what goes on inside the computer” for each of nine BASIC statements.
TL;DR: An historical overview of computational complexity is presented and emphasis is on the fundamental issues of defining the intrinsic computational complexity of a problem and proving upper and lower bounds on the complexity of problems.
Abstract: An historical overview of computational complexity is presented. Emphasis is on the fundamental issues of defining the intrinsic computational complexity of a problem and proving upper and lower bounds on the complexity of problems. Probabilistic and parallel computation are discussed.
TL;DR: Nicholas P. Vitalari and Gary W. Dickson's current research interests involve the relationship between human problem solving and the development of decisionsupporting systems.
Abstract: Nicholas P. Vitalarrs current research interests are in the role of cognitive models in systems analysis, training requirements for systems analysis, structured analysis methods, and the sociology of computing at work and in the home. He may be reached through CSNET at VITALARI@UCI-2OB. Gary W. Dickson's current research interests involve the relationship between human problem solving and the development of decisionsupporting systems. Authors' Present Addresses: Nicholas P. Vitalari, Graduate School of Management, University of Californialrvine, Irvine, CA 92717; Gary W. Dickson, School of Management, University of Minnesota, 217 19th Ave. South, Minneapolis, MN 55455 Permission to copy without fee all or part of this material is granted provided that the copies are not made or distributed for direct commercial advantage, the ACM copyright notice and the title of the publication and its date appear, and notice is given that copying is by permission of the Association for Computing Machinery. To copy otherwise, or to republish, requires a fee and/or specific permission. © 1983 ACM 0001-0782/83/1100-0948 75¢
TL;DR: It is shown that an analytical approach can yield insights into competing filter design and give expected values for the goodness-of-hash transformations not available with simulation.
Abstract: This note deals with a paper by Gremillion demonstrating the simulation approach to the design of a Bloom filter. It is shown that an analytical approach can yield insights into competing filter design and give expected values for the goodness-of-hash transformations not available with simulation. On the other hand, simulation gives insight into what can be expected with available hash transformation not available from an analytic approach.
TL;DR: This report discusses the documentation requirements of the development process and describes a prototype system for constructing and maintaining this documentation information and indicates the many remaining open issues and the direction to be taken in the pursuit of solutions.
Abstract: : Automated program transformation systems are emerging as the basis for a new programming methodology in which high-level, understandable specifications are transformed into efficient programs. Subsequent modification of the original specification will be dealt with by reimplementation of the specification. For such a system to be practical, these reimplementations must occur relatively quickly and reliably, in comparison with the original implementation. We believe the reimplementation requirement necessitates that a formal document--the program development--be constructed during the development process to explain the resulting implementation to future maintainters of the specification. The overall goal of our work has been to develop a language for capturing and explaining these developments and the resulting implementations. This language must be capable of expressing: the implementor's goal structure, all program manipulations necessary for implementation and optimization, and plans of such optimizations. In this report, we discuss the documentation requirements of the development process and then describe a prototype system for constructing and maintaining this documentation information. Finally, we indicate the many remaining open issues and the direction to be taken in the pursuit of solutions. (Author)
TL;DR: A tree data structure for representing multidimensional digital binary images and an algorithm for constructing the tree of a d-dimensional binary image from the trees of its (d - 1 )-dimensional cross sections are given.
Abstract: A tree data structure for representing multidimensional digital binary images is described. The method is based on recursive subdivision of the d-dimensional space into 2d hyperoctants. An algorithm for constructing the tree of a d-dimensional binary image from the trees of its (d - 1 )-dimensional cross sections is given. The computational advantages of the data structure and the algorithm are demonstrated both theoretically and in application to a three-dimensional reconstruction of a human brain.
TL;DR: The Amsterdam Compiler Kit is an integrated collection of programs designed to simplify the task of producing portable (cross) compilers and interpreters.
Abstract: The Amsterdam Compiler Kit is an integrated collection of programs designed to simplify the task of producing portable (cross) compilers and interpreters. For each language to be compiled, a program (called a front end) must be written to translate the source program into a common intermediate code. This intermediate code can be optimized and then either directly interpreted or translated to the assembly language of the desired target machine. The paper describes the various pieces of the tool kit in some detail, as well as discussing the overall strategy.
TL;DR: The data indicate that various job factors are perceived as stressful by respondents, but the stress levels reported by respondents are not as excessive as have been found in studies of other occupational groups.
Abstract: This study examines occupational stress among information systems personnel A self-report stress and health behavior instrument was completed by 580 respondents in 18 large corporations in the midwestern and southwestern sections of the United States The data indicate that various job factors are perceived as stressful by respondents However, the stress levels reported by respondents are not as excessive as have been found in studies of other occupational groups
TL;DR: You-Dong Liang and Brian Barsky's research interest include computeraided geometric design and modeling, and interactive three-dimensional computer graphics.
Abstract: You-Dong Liang's primary research interest is computeraided geometric design. Brian Barsky's research interest include computeraided geometric design and modeling, and interactive three-dimensional computer graphics. Authors' Present Addresses: You-Dong Hang. Department of Mathematics, Zhejiang University, Hangzhou, Zhejiang, People's Republic of China; Brian A. Barsky, Berkeley Computer Graphics Laboratory, Computer Science Division, University of California, Berkeley. California 94720.