reserve n for Nat,
  i,j for Nat,
  r,s,r1,s1,r2,s2,r9,s9 for Real,
  p,q for Point of TOP-REAL 2,
  G for Go-board,
  x,y for set,
  v for Point of Euclid 2;

theorem Th91:
  for M being non empty MetrSpace, p being Point of M, q being
Point of TopSpaceMetr M, r being Real st p = q & r > 0 holds Ball (p, r)
  is a_neighborhood of q
proof
  let M be non empty MetrSpace, p be Point of M, q be Point of TopSpaceMetr M,
  r be Real;
  reconsider A = Ball (p, r) as Subset of TopSpaceMetr M by TOPMETR:12;
  assume p = q & r > 0;
  then q in A by Th1;
  hence thesis by CONNSP_2:3,TOPMETR:14;
end;
