A Database Interface for Complex Objects

Marcel Holsheimer, Rolf A. de By, R.A. de By, Hassan Ait-Kaci

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We describe a formal design for a logical query language using psi-terms as data structures to interact effectively and efficiently with a relational database. The structure of psi-terms provides an adequate representation for so-called complex objects. They generalize conventional terms used in logic programming: they are typed attributed structures, ordered thanks to a subtype ordering. Unification of psi-terms is an effective means for integrating multiple inheritance and partial information into a deduction process. We define a compact database representation for psi-terms, representing part of the subtyping relation in the database as well. We describe a retrieval algorithm based on an abstract interpretation of the psi-term unification process and prove its formal correctness. This algorithm is efficient in that it incrementally retrieves only additional facts that are actually needed by a query, and never retrieves the same fact twice.
Original languageUndefined
Place of PublicationAvenue Victor Hugo 85, 92563 Rueil Malmaison Cedex, France
PublisherDigital Equipment Corporation, Paris Research Laboratory
Number of pages34
Publication statusPublished - Mar 1993

Publication series

NamePRL Research Reports
PublisherDigital Equipment Corporation, Paris Research Laboratory


  • Relational Databases
  • Deductive Databases
  • IR-64281
  • Complex Objects
  • Abstract Interpretation
  • Psi-Terms
  • Information Retrieval
  • EWI-10861
  • Inheritance
  • Logical Query Languages

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