BULLETIN OF THE MALAYSIAN MATHEMATICAL SCIENCES SOCIETY, cilt.45, sa.2, ss.663-675, 2022 (SCI-Expanded)
In this paper, we classify all isolated, completely isolated, and (left/right) convex subsemigroups of C-n, the semigroup of all order-preserving and decreasing transformations on X-n = (1, ..., n) under its natural order. Moreover, we find the rank of each convex subsemigroup of C-n.