
theorem Th1:
  for F being Field holds revf(F).1.F = 1.F
proof
  let F be Field;
A1: 1.F is Element of NonZero F by STRUCT_0:2;
  then 1.F*1.F = 1.F by REALSET2:6;
  hence thesis by A1,REALSET2:22;
end;
