
theorem
  for L being non empty TopSpace, N being net of L for c being Point of
  L st c in Lim N holds c is_a_cluster_point_of N
proof
  let L be non empty TopSpace, N be net of L, c be Point of L such that
A1: c in Lim N;
  let O be a_neighborhood of c;
  N is_eventually_in O by A1,YELLOW_6:def 15;
  hence thesis by YELLOW_6:19;
end;
