Proof. Suppose S is the union of the left strongly simple subsemigroups Sα,
α ∈ Y . Then we have a ∈ (Sa2Sa] for every a ∈ S. In fact: Let a ∈ S, and let
a ∈ Sα for some α ∈ Y . Since Sα is a left strongly simple ordered semigroup
and a, a2 ∈ Sα, by Lemma 6, we have a ∈ (Sαa2Sαa]Sα
⊆ (Sa2Sa].
Intra-regular semigroups (resp. ordered semigroups) play an essential role in
studying the structure of semigroups (resp. ordered semigroups). Decomposition
of an intra-regular semigroup into simple components can be found in
[1] and [12]. Decomposition of an intra-regular ordered semigroup into simple
components can be found in [4]. The present paper deals with the decomposition
of ordered semigroups into left strongly simple components, that is, into
components which are both simple and left quasi-regular. We prove that an
ordered semigroup S is a semilattice of left strongly simple semigroups if and
only if every left ideal of S is an intra-regular subsemigroup of S. An ordered
semigroup S is a semilattice of left strongly simple semigroups if and only if
every left ideal of S is a semisimple subsemigroup of S.