The concepts of row and
column bases for an element of ℬX, the semigroup of binary relations on a set X, are
introduced by interpreting a binary relation as a boolean matrix; these ideas are then
used to characterize the Green’s equivalences on ℬX. It is shown that the class of
idempotent relations whose rows and columns form independent sets coincides with
the class of partial order relations on subsets of X. Regularity in ℬX is investigated
using these results.