 reserve n for Nat;

theorem
   for R being Ring, S being R-homomorphic Ring
   for h being Homomorphism of R,S holds (PolyHom h).(1_.R) = 1_.S
   proof
     let R be Ring, S be R-homomorphic Ring; let h be Homomorphism of R,S;
     thus
     (PolyHom h).(1_.R) = (PolyHom h).(1_(Polynom-Ring R)) by POLYNOM3:def 10
     .= 1_(Polynom-Ring S) by GROUP_1:def 13 .= 1_.S by POLYNOM3:def 10;
   end;
