For theLet $G$ be a classical groups (including $U(n)$$\operatorname U(n)$, $SO(n)$$\operatorname{SO}(n)$, and $Sp(2n)$$\operatorname{Sp}(2n)$), let Vand $V$ be the defining representation (the natural inclusion of $G$ into $GL(n,C)$$\operatorname{GL}(n,C)$), when. When are $S^kV$ and $Λ^kV$$\bigwedge\nolimits^kV$ irreducible ?