relation
1. A subset of the {product} of two sets, R : A
x B. If (a, b) is an element of R then we write a R b,
meaning a is related to b by R. A relation may be:
{reflexive} (a R a), {symmetric} (a R b ◦> b R a),
{transitive} (a R b & b R c ◦> a R c), {antisymmetric} (a R b
& b R a ◦> a ◦ b) or {total} (a R b or b R a).
See {equivalence relation}, {partial ordering}, {pre-order},
{total ordering}.
2. A {table} in a {relational database}.
(1995-02-28)