A form of Kadison's theorem used in §6: if A\mathfrak A acts irreducibly on H\mathcal H and x,yHx,y\in\mathcal H, then there exists AAA\in\mathfrak A with Ax=yAx=y.

Remarks

Key property (paper use):

  • Lets Shale characterize "relative normalizability" of states via F(X)=E(AXA)F(X)=E(A^*XA).
Examples
  • In B(H)B(\mathcal H), take AA to be a rank-one operator sending xx to yy.