A normal orthodox semigroup is an orthodox semigroup whose idempotent elements form a normal band.We deal with congruces on a normal orthodox semigroup with an
In this paper we discuss the basic properties of hyper relation Ri, which is upgraded from the base relation R. The relationship between Ri and R is considered.
A graph is equitably k-colorable if its vertices can be partitioned into k independent sets of as near equal sizes as possible. In this paper, we determine a su