Supporting Valid Time: An Historical Algebra.

Abstract

The authors define an historical algebra for historical relations. This historical algebra, a straightforward extension of the conventional relational algebra, supports valid time, the time when an object or relationship in the enterprise being modeled is valid. Historical versions of the five relational operators union, difference, cartesian product, selection, and projection are defined and a new operator, historical derivation, is introduced. The algebra includes aggregates and is shown to have the expressive power of the temporal query language TQuel. The algebra is consistent with the user-oriented model of historical relations as space-filling objects and satisfies all but one of the associative, commutative, and distributive tautologies involving union, difference, and cartesian product. Keywords: Data base management systems.

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Document Details

Document Type
Technical Report
Publication Date
Aug 01, 1987
Accession Number
ADA187740

Entities

People

  • Edwin Mckenzie
  • Richard Snodgrass

Organizations

  • University of North Carolina at Chapel Hill

Tags

Communities of Interest

  • Energy and Power Technologies

DTIC Thesaurus Topics

  • Air Force
  • Computer Science
  • Computers
  • Database Management Systems
  • Databases
  • Information Science
  • Information Systems
  • Language
  • New York
  • North Carolina
  • Relational Database Management Systems
  • Relational Databases
  • Set Theory
  • Three Dimensional
  • United States
  • Universities
  • Virginia

Readers

  • Database Systems and Applications
  • Graph Algorithms and Convex Optimization.
  • Military History / Militaries and War Studies

Technology Areas

  • Space