Radford's S^4 formula for co-Frobenius Hopf algebras
arXiv:math/0511535
Abstract
This note extends Radford's formula for the fourth power of the antipode of a finite dimensional Hopf algebra to co-Frobenius Hopf algebras and studies equivalent conditions to a Hopf algebra being involutory for finite dimensional and co-Frobenius Hopf algebras.
To appear in Journal of Algebra