一个Hopf代数的余代数自同构

Let k be an algebraically closed field, q a nonzero element in k with q not being roots of unity. Let C be a Hopf algebra, which is generated, as an algebra, by a group-like element x and a semi-primitive element y. In this paper, the coalgebra automorphisms of C are investigated. The graded coalgebra automorphisms of C are described. Moreover, The group of greded coalgebra automorphisms of C is described.