Transitive closure
In mathematics, the transitive closure of a binary relation
on a set X is the smallest transitive relation on X that contains .In more concrete terms the transitive closure of R is the relation R* such that xR*y if xRy, or if xRz for some z with zRy, or if xRz and zRw and wRy for some z and w in X, and so on for any number of intermediates. If X is the set of humans (alive or dead) and R is the relation 'parent of', then xR*y means y is a direct descendant of x.
