--- Example D (A_D, w = diag(2e-1, 2f-1, 1, 1))
  p magic: True ; A p = p A: True ; noncommutative model: max||[p_ab,p_cd]|| = 0.851
  entries of w partial isometries: True ; P', Q' magic: True ; A P' = Q' A: True
  PF vector [0.2808 0.2808 0.2192 0.2192] preserved by P' and Q': True
  max partial-isometry defect of w_(alpha,beta), ALL words of length <= 7: 9.87e-15
  Delta(s) = s(x)s: True ; Delta(t) = t(x)t: True ; ||[s,t]|| = 3.402
  A_D^2 > 0: True ; out-degrees of J - A_D: [1, 1, 2, 2]
--- Example E (A_E = C_4 + I, u of H_2^+ on {1,3}, 1 on {2,4})
  p magic: True ; A p = p A: True ; noncommutative model: max||[p_ab,p_cd]|| = 0.621
  entries of w partial isometries: True ; P', Q' magic: True ; A P' = Q' A: True
  PF vector [0.25 0.25 0.25 0.25] preserved by P' and Q': True
  max partial-isometry defect of w_(alpha,beta), ALL words of length <= 7: 9.60e-15
  a,b,c,d recovered from p: True
  Delta(a)=a(x)a+b(x)c: True  Delta(b)=a(x)b+b(x)d: True  Delta(c)=c(x)a+d(x)c: True  Delta(d)=c(x)b+d(x)d: True
  g = 2a^2 - 1 group-like (Delta(g) = g(x)g): True ; g != 1: True
  canonical u -> p at level 2: max defect = 0.378 (>0: fails, Theorem C)
DONE v3
