theorem Th61:
  (for v,w holds v|still_not-bound_in p = w|still_not-bound_in p
  implies (J,v |= p iff J,w |= p)) implies for v,w holds v|still_not-bound_in
'not' p = w|still_not-bound_in 'not' p implies (J,v |= 'not' p iff J,w |= 'not'
  p)
proof
  assume
A1: for v,w holds v|still_not-bound_in p = w|still_not-bound_in p
  implies (J,v |= p iff J,w |= p);
  let v,w;
A2: still_not-bound_in 'not' p = still_not-bound_in p by QC_LANG3:7;
  assume v|still_not-bound_in 'not' p = w|still_not-bound_in 'not' p;
  then not J,v |= p iff not J,w |= p by A1,A2;
  hence thesis by VALUAT_1:17;
end;
