Let H be a finite dimensional Hopf algebra over a field k and A/B be a right H-Galois extension. In this note the relationship of cotorsion dimensions between A and B will be studied. We prove that r.cot.D(A) <= r.cot.D(B) +1.D(H). Moreover, we give some sufficient conditions for which r.cot.D(A) = r.cot.D(B). As applications, we obtain some results about cotorsion dimension of the smash product.
机构:
School of Mathematics, Southeast University, Nanjing
School of Science, Jinling Institute of Technology, NanjingSchool of Mathematics, Southeast University, Nanjing