
theorem Th20:
  for F being Field holds for x being Element of NonZero F holds
  ovf(F).(x,x) = 1.F
proof
  let F be Field;
  let x be Element of NonZero F;
  thus ovf(F).(x,x) = omf(F).(x,revf(F).x) by Def2
    .=1.F by REALSET2:def 6;
end;
