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;

theorem Th3:
  aleph A is infinite
proof
  {} c= A;
  then omega c= aleph A by CARD_1:23,46;
  hence thesis;
end;
