摘要
First, some properties of H separable rings are discussed, and it is shown that the H separable ring A can be represented as the tensor product of its subrings under certain conditions. Secondly, a necessary and sufficient condition is obtained for a Hopf Galois extension A/B to be H separable. Finally, some equivalent conditions are got for an H separable ring A to be a Hopf Galois extension over a certain subring B .
