Cohomology for partial actions of Hopf algebras

In this work, the cohomology theory for partial actions of co-commutative Hopf algebras on commutative algebras is formulated. This theory generalizes the cohomology theory for Hopf algebras introduced by Sweedler and the cohomology theory for partial group actions, introduced by Dokuchaev and Khrypchenko. Some nontrivial examples, not coming from groups are constructed. Given a partial action of a cocommutative Hopf algebra H over a commutative algebra A, we prove that there exists a new Hopf algebra (A) over tilde, over a commutative ring E(A), upon which H still acts partially and which gives rise to the same cohomologies as the original algebra A. We also study the partially cleft extensions of commutative algebras by partial actions of cocommutative Hopf algebras and prove that these partially cleft extensions can be viewed as a cleft extensions by Hopf algebroids. (C) 2019 Elsevier Inc. All rights reserved.