By using the
Y(gl(m|n)) super Yangian symmetry of the
SU(m|n) supersymmetric Haldane
x2013;Shastry
spin chain, we show that the partition function of this model satisfies a duality relation under the exchange of bosonic and fermionic
spin degrees of freedom. As a byproduct of this study of the duality relation, we find a novel combinatorial formula for the super Schur polynomials associated with some irreducible representations of the
Y(gl(m|n)) Yangian algebra. Finally, we reveal an intimate connection between the global
SU(m|n) symmetry of a
spin chain and the boson
x2013;fermion duality relation.