  We investigate the poset of skew diagrams ordered by adding or forming the
union of skew diagrams. We will show that a skew diagram which has at least n
convex corners to the upper left and also to the lower right is larger than the
skew diagram consisting of n disconnected single boxes. Using this property, we
obtain lower bounds for the number of components, constituents and pairs of
components which differ by one box in a given skew character.
