A generalization of Roberts-Tannaka duality theorem

A Galois type theorem in von Neumann algebras

“…The author would like to express his thanks to Prof. Y. Katayama and the referee of this paper for informations on Ikeshoji's paper [5].…”

“…Ikeshoji [5] shows a theorem of the above type for locally compact group actions on von Neumann algebras. Also, as a theory of this type for discrete groups, in [2], we decided an automorphism fixing the fixed point algebra of a discrete automorphism group.…”