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;
reserve a,b for Aleph;
reserve O for Ordinal,
        F for Subset of omega;

theorem
  card F c= order_type_of RelIncl F
proof
  card F = card order_type_of RelIncl F by Th7;
  hence thesis by CARD_1:8;
end;
