In regular and in intra-regular ordered semigroups the
ideals and the interior ideals coincide. In regular and in intra-regular
poe-semigroups the ideal elements and the interior ideal elements coincide.
In an attempt to show the similarity between the theory of ordered
semigroups and the theory of fuzzy ordered semigroups, we prove here
that in regular and in intra-regular ordered semigroups the fuzzy ideals
and the fuzzy interior ideals coincide. We also prove that A is an interior
ideal of an ordered semigroup S if and only if the characteristic function
fA is a fuzzy interior ideal of S. We nally introduce the concept of a
fuzzy simple ordered semigroup, we prove that an ordered semigroup is
simple if and only if it is fuzzy simple, and we characterize the simple
ordered semigroups in terms of fuzzy interior ideals.