  In this paper we classify the multiplicity-free skew characters of the
symmetric group. Furthermore we show that the Schubert calculus is equivalent
to that of skew characters in the following sense: If we decompose the product
of two Schubert classes we get the same as if we decompose a skew character and
replace the irreducible characters by Schubert classes of the `inverse'
partitions (Theorem 4.2).
