reserve X for RealUnitarySpace;
reserve x, y, z, g, g1, g2 for Point of X;
reserve a, q, r for Real;
reserve seq, seq1, seq2, seq9 for sequence of X;
reserve k, n, m, m1, m2 for Nat;

theorem
  r >= 0 implies x in cl_Ball(x,r)
proof
  assume r >= 0;
  then dist(x,x) <= r by BHSP_1:34;
  hence thesis by Th48;
end;
