Abstract:
Let $H$ be a finite-dimensional Hopf algebra over a field $k$, and let $A$ be an $H$-module algebra. In this paper, we discuss the cotorsion dimension of the smash product $A\mathbin{\#}H$. We prove that
$$
\mathrm{l.cot.D}(A\mathbin{\#}H) \leq \mathrm{l.cot.D}(A) + \mathrm{r.D}(H),
$$
which generalizes the result of group rings. Moreover, we give some sufficient conditions for which
$$
\mathrm{l.cot.D}(A\mathbin{\#}H) =\mathrm{l.cot.D}(A).
$$
As applications, we study the invariants of IF properties and Gorenstein global dimensions.