theorem
  {p7 where p7 is Point of TOP-REAL 2: -p7`2<=p7`1 } is closed Subset of
  TOP-REAL 2 & {p7 where p7 is Point of TOP-REAL 2: p7`1<=-p7`2 } is closed
  Subset of TOP-REAL 2 by Lm17,Lm20;
