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 Th36:
  {x} c= O implies order_type_of RelIncl {x} = 1
proof
  card {x} = 1 by CARD_2:42;
  hence thesis by Th35;
end;
