Literature/1975/Chen


 * http://dl.acm.org/citation.cfm?id=1095277.1095279

Authors

 * Peter Chen
 * (1973) Ph.D. in computer science/applied mathematics, Harvard University.
 * (1974-1978) Assistant Professor, MIT Sloan School of Management.
 * (1978-1984) Professor, University of California, Los Angeles, Management School.
 * (1983- ) M. J. Foster Distinguished Chair Professor of Computer Science, Louisiana State University.

Contents

 * DEPARTMENT: ACM Transactions on Database Systems abstracts


 * The entity-relationship model&#58; toward a unified view of data
 * Peter Pin-Shan Chen
 * Pages: 9-9

A data model, called the entity-relationship model, is proposed. This model incorporates some of the important semantic information in the real world. A special diagramatic technique is introduced as a tool for data base design. An example of data base design and description using the model and the diagramatic technique is given. Some implications on data integrity, information retrieval, and data manipulation are discussed.The entity-relationship model can be used as a basis for unification of different views of data: the network model, the relational model, and the entity set model. Semantic ambiguities in these models are analyzed. Possible ways to derive their views of data from the entity-relationship model are presented.


 * On the encipherment of search trees and random access files
 * R. Bayer, J. K. Metzger, München W. Germany
 * Pages: 10-10

The securing of information in indexed, random access files by means of privacy transformations must be considered as a problem distinct from that for sequential files. Not only must processing overhead due to encrypting be considered, but also must threats to encipherment arising from updating and the file structure itself be countered. A general encipherment scheme is proposed for files maintained in a paged structure on secondary storage. This is then applied to the encipherment of indexes organized as B-trees, a particular type of multiway search tree. Threats to the encipherment of B-trees, especially relating to updating, are examined, and counter-measures proposed for each. In addition, the effect of encipherment on file access and update, on paging mechanisms, and on files related to the enciphered index are discussed. Many of the concepts presented here may be readily transferred to other forms of multiway index trees and to binary search trees.


 * Optimal allocation of resources in distributed information networks
 * Samy Mahmoud, J. S. Riordon
 * Pages: 11-11

The problems of file allocation and capacity assignment in a fixed topology distributed computer network are examined. These two aspects of the design are tightly coupled through an average message delay constraint. The objective is to allocate copies of information files to network nodes and capacities to network links so that a minimum cost is achieved subject to network delay and file availability constraints. A model for solving the problem is formulated and the resulting optimization problem is shown to fall into a class of non-linear integer programming problems. Deterministic techniques for solving this class of problems are computationally cumbersome even for small sized problems. A new heuristic algorithm is developed, based on a decomposition technique which greatly reduces the computational complexity of the problem. Numerical results for a variety of network configurations indicate that the heuristic algorithm, while not theoretically convergent, yields practicable low cost solutions with substantial savings in computer processing time and storage requirements. Moreover, it is shown that this algorithm is capable of solving realistic network problems whose solution using deterministic techniques is computationally intractable.


 * The design of a rotating associative array memory for a relational data base management application
 * C. S. Lin, Diane C. P. Smith
 * Pages: 12-12

There are significant advantages to tailoring hardware storage devices to support high level data models in very large data bases. A storage device that can assume some of the data selection functions traditionally performed by the CPU can substantially reduce the amount of data to be transferred to the CPU. This reduction together with increased concurrency of CPU and device operation result in increased data rates and lower response times. By designing the device to support one specific data model, greater efficiency can be achieved than in devices designed to be a compromise in their support of several different models. The number and complexity of the functions performed by the device can be drastically reduced, along with its development and production costs. In this paper we describe the design and usage of an associative array memory using a rotating storage device which is tailored to support the relational model of E.F. Codd.


 * Restructuring for large data bases&#58; three levels of abstraction
 * Shamkant B. Navathe, James P. Fry
 * Pages: 13-13

The development of a powerful restructuring function involves two important components - the unambiguous specification of the restructuring operations and the realization of these operations in a software system. We direct our efforts to the first component in the belief that a precise specification will provide a firm foundation for restructuring algorithms and implementations. This paper defines completely the semantics of the restructuring of tree structured data bases.The delineation of the restructuring function is accomplished by formulating three different levels of abstraction, with each level of abstraction representing successively more detailed semantics of the function.At the first level of abstraction, the schema modification, three types are identified: naming, combining and relating, and are further divided into eight schema operations. The second level of abstraction, the instance operations, constitutes the transformations on the data instances. They are divided into group operations such as replication, factoring, union and group relation operations such as collapsing, refinement, fusion etc. The final level, the item values operations, includes the actual item operations such as copy value, delete value, or create a null value.


 * A data base management facility for automatic generation of data base managers
 * David W. Stemple
 * Pages: 14-14

This paper presents a facility for the implementation of data base management systems having high degrees of horizontal data independence, i.e. independence from chosen logical properties of a data base as opposed to vertical independence from storage structures. The facility consists of a high level language for the specification of virtual data base managers, a compiler from this language to a pseudo-machine language, and an interpreter for the pseudo-machine language.It is shown how this facility can be used to produce efficient data base management systems with any degree of both horizontal and vertical data independence. Two key features of this tool are the compilation of tailored data base managers from individual schemas and multiple levels of optional binding.

Wikimedia

 * Peter Chen
 * The hypertext concept, which makes the World Wide Web extremely popular, is very similar to the main concept in the ER model. Dr. Chen is currently investigating this linkage as an invited expert of several XML working groups of the World Wide Web Consortium (W3C).
 * The ER model also serves as the foundation of some of the recent work on Object-oriented analysis and design methodologies and Semantic Web. The UML modeling language has its roots in the ER model.

Chronology

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