/* Compute the transitive closure of the FUNCTION on the relation R
with SIZE vertices.
If R (NODE-1, NODE-2) then on exit FUNCTION[NODE - 1] was extended
(unioned) with FUNCTION[NODE - 2]. */
/* Compute the transitive closure of the FUNCTION on the relation R
with SIZE vertices.
If R (NODE-1, NODE-2) then on exit FUNCTION[NODE - 1] was extended
(unioned) with FUNCTION[NODE - 2]. */