reserve n for non zero Nat,
  j,k,l,m for Nat,
  g,h,i for Integer;

theorem
  for h,i be Integer st ( h >= 0 & i >= 0 or h < 0 & i < 0 ) & h mod 2
to_power n = i mod 2 to_power n holds 2sComplement(n,h) = 2sComplement(n,i) by
