... xzy )12 Ta l~p cong thlic tinh aI2b21(-a)12, a, bE A ( a 1 = I I a12b21 (-a)12 I I b (1 -a In + 0) l ) I (CQt cua a12) (ab = In + I I I l b -aba -ba (D()ng 0 01 0\ \ Ap dl,lng cong thlic tren ... Truong hQp t6ng quat: H *-Cen(GLn(A)) ~:3 h = (hjj)E H: h ~ Cen(GLn(A)) A/Rad(A) la vanh chlnh qui von Neumann Den : :3 X E A/Rad(A): hn2 = hn2' ~ hn2 Suy fa : z:= hn 2.x.hn - hn E Rad(A) ~ Bi;}t ... GII(A,B): 54 c.l Tntoc hSt, ta co A 1a vanh chlnh qui Vall Neumann nen AIB Ia vanh chfIlh qui von Neumann Do (AIB)/ Rad(A/B) cling Ia vanh chinh qui van Neumann c.2 GQi H'= q>(H), q>(En(A) )...