Base> Given a relation R (in a relational dataBase), attriBute Y of R is functionally dependent on attriBute X of R and X of R functionally determines Y of R (in symBols R.X -> R.Y) if and only if each X in R has associated with it precisely one Y in R (at any one time). AttriButes X and Y may Be composite. This is very close to a function in the mathematical sense. (1997-09-01)