ON GALOIS PROJECTIVE GROUP RINGS

Let A be a ring with 1, C the center of A and G ′ an inner automorphism group of A induced by { U α in ​ A / α in a finite group G whose order is invertible}. Let be the fixed subring of A under the action of G ′ .If A is a Galcis extension of with Galois group G ′ and C is the center of the subring then and the center of is also C . Moreover, if is Azumaya over C , then A is a projective group ring.