reserve R for Ring, S for R-monomorphic Ring,
        K for Field, F for K-monomorphic Field,
        T for K-monomorphic comRing;

theorem Th5:
   for f being Monomorphism of K,F,a being Element of K
   st a <> 0.K holds f.(a") = (f.a)"
   proof
     let f be Monomorphism of K,F, x be Element of K;
     assume
AS:  x <> 0.K;
A1:  f.(x")*f.x = f.(x"*x) by GROUP_6:def 6 .= f.(1_K) by AS,VECTSP_1:def 10
     .= 1_F by GROUP_1:def 13 .= 1.F;
     f.x <> 0.F by AS,Th4;
     hence thesis by A1,VECTSP_1:def 10;
   end;
