
 PlanetMath: topological space 
  Crossreferences: metric topology, product topology, subspace topology, indiscrete topology, power set, discrete topology, coarser, finer, complement, subsets 
  it might be interesting to note that you can equivalently define a topology in terms of it's closed sets, by demorgan's set laws. 
  i can't seem to find a definition for the topology induced by a metric space either, which is something you probably want to add. 
 planetmath.org /encyclopedia/Topology.html (168 words) 
