reserve i,j for Nat;
reserve A,B for Ring;
reserve K, L for Field;

theorem
  for x be Element of F_Complex holds
    F_Complex is (Polynom-Ring F_Rat)-homomorphic
  proof
    let x be Element of F_Complex;
    hom_Ext_eval(x,F_Rat) is RingHomomorphism;
    hence thesis;
  end;
