reserve p1,p2,p3,p4,p5,p6,p,pc for Point of TOP-REAL 2;
reserve a,b,c,r,s for Real;
reserve c1,c2,c3 for Element of COMPLEX;

theorem
  (p1-p2)`1 = p1`1 - p2`1 & (p1-p2)`2 = p1`2 - p2`2 by Lm15;
