  In this note we give defining relations of an $\mathfrak{sl}_{n+1}[t]$-module
defined by the fusion product of simple $\mathfrak{sl}_{n+1}$-modules whose
highest weights are multiples of a given fundamental weight. From this result
we obtain a surjective homomorphism between two fusion products, which can be
considered as a current algebra analog of Schur positivity.
