I am unable to find any reference on the meaning of $\pi^\psi$, where $\pi$ and $\psi$ are two permutations of the set $\{1,2,3, \ldots ,n\}$. E.g, $(1,2,3,5,4)^{(2,3,5)}$
Incidentally the package GAP provides this operation, but the manual says nothing about this. Thanks