reserve r for Real;
reserve a, b for Real;
reserve T for non empty TopSpace;
reserve A for non empty SubSpace of T;
reserve P,Q for Subset of T,
  p for Point of T;
reserve M for non empty MetrSpace,
  p for Point of M;
reserve A for non empty SubSpace of M;
reserve F,G for Subset-Family of M;

theorem Th14:
  for r being Real for M being triangle MetrStruct, p being
  Point of M for P being Subset of TopSpaceMetr(M) st P = Ball(p,r) holds P is
  open
by PCOMPS_1:29;
