reserve k,n,m for Nat,
  A,B,C for Ordinal,
  X for set,
  x,y,z for object;
reserve f,g,h,fx for Function,
  K,M,N for Cardinal,
  phi,psi for
  Ordinal-Sequence;
reserve a,b for Aleph;

theorem Th19:
  M c= exp(M,a)
proof
  1 in a by Lm1,Th15;
  then M = 0 & {} c= exp(M,a) or exp(M,1) c= exp(M,a) & exp(M,1) = M by
CARD_2:27,93;
  hence thesis;
end;
