设M是超有限Ⅱ1型因子,D是M的Cartan子代数,T是对角为D的M的σ-弱闭的子代数(简称Cartan双模代数)并且生成M.设Ф是T到T上的σ-弱连续满线性等距,则Ф可扩张成从M到M上的等距.设Ф是T到T上的映射(没假设线性),满足任给a,b∈T,T上存在σ-弱连续满线性等距Фa,b(与a,b有关),使得Фa.b(a)=Ф(a),Фa,b(b)=Ф(b),则Ф是线性等距.
Let M be a hyperfinite factor of type Ⅱ1, D is a Cartan masa of M, T be a Cartan subalgebas of M with diagonal D which generates M. If Ф : T → T be an σ-weakly continuous (Banach) isometry, then Ф can be extended a isometry on M.If a map Ф : T → T satisfies that for every pair a, b ∈ T, there is a a-weakly continuous isometry Фa,b on T such that Фa,b(a) =Фa,Фa,b(b)=Ф(b) then Ф is a linear isometry.