reserve a,b,r for non unit non zero Real;
reserve X for non empty set,
        x for Tuple of 4,X;
reserve V             for RealLinearSpace,
        A,B,C,P,Q,R,S for Element of V;

theorem
  for x being Element of TOP-REAL 1
  for p being Tuple of 1,REAL st
  p = x holds - x = - p;
