
theorem
  for F being Field holds for x being Element of F holds osf(F).(x,x) = 0.F
proof
  let F be Field;
  let x be Element of F;
  thus osf(F).(x,x) = (the addF of F).(x,(comp F).x) by Def1
    .= x-x by VECTSP_1:def 13
    .= 0.F by RLVECT_1:5;
end;
