Functional dependencies and the semilattice of closed classes

  • János Demetrovics
  • Leonid O. Libkin
  • Ilya B. Muchnik
Conference paper
Part of the Lecture Notes in Computer Science book series (LNCS, volume 364)


In this paper we present the semilattice-theoretical approach to the investigation of the relational datamodels. It is known that the poset of closures is a model of changing databases. We show that it is in fact a lattice isomorphic to the subsemilattice-lattice of free semilattice, and the arbitrary subsemilattice-lattices can be considered as a model of restrictedly changing databases. The properties of these lattices in the context of database problems are studied. We also discuss the separation and dimension problems and establish some estimates.

Key words

database semilattice lattice closure operator rank function distributive standard and neutral elements direct product ordinal sum 


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Copyright information

© Springer-Verlag Berlin Heidelberg 1989

Authors and Affiliations

  • János Demetrovics
    • 1
  • Leonid O. Libkin
    • 2
  • Ilya B. Muchnik
    • 3
  1. 1.Computer and Automation Institute Hungarian Academy of SciencesBudapestHungary
  2. 2.MoscowUSSR
  3. 3.Institute of Control SciencesMoscowUSSR

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