reserve
  x, y for object,
  i, n for Nat,
  r, s for Real,
  f1, f2 for n-element real-valued FinSequence;
reserve e, e1 for Point of Euclid n;

theorem Th12:
  for e being Point of Euclid 0 holds OpenHypercube(e,r) = {{}} by CARD_3:10;
