equivalence relation

from The Free On-line Dictionary of Computing (8 July 2008)

equivalence relation

   <mathematics> A relation R on a set including elements a, b,
   c, which is reflexive (a R a), symmetric (a R b => b R a) and
   transitive (a R b R c => a R c).  An equivalence relation
   defines an {equivalence} class.

   See also {partial equivalence relation}.

   (1996-05-13)