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,y being Element of TOP-REAL 1 for a,b being Real st
  x = <* a *> & y = <* b *> holds x - y = <* a - b *> by RVSUM_1:29;
