Armstrong’s Axioms

Posted By on October 7, 2014


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Functional Dependancy
Trivial Functional Dependency

Armstrong’s Axioms

If F is set of functional dependencies then the closure of F, denoted as F+, is the set of all functional dependencies logically implied by F. Armstrong’s Axioms are set of rules, when applied repeatedly generates closure of functional dependencies.

  • Reflexive rule: If alpha is a set of attributes and beta is_subset_of alpha, then alpha holds beta.
  • Augmentation rule: if a → b holds and y is attribute set, then ay → by also holds. That is adding attributes in dependencies, does not change the basic dependencies.
  • Transitivity rule: Same as transitive rule in algebra, if a → b holds and b → c holds then a → c also hold. a → b is called as a functionally determines b
Functional Dependancy
Trivial Functional Dependency

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Posted by Akash Kurup

Founder and C.E.O, World4Engineers Educationist and Entrepreneur by passion. Orator and blogger by hobby

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