title: What does it mean by "Path Matrix" and "Transitive Closure" of a graph (Directed and Undirected)?
body: <p>I the discussion of various graph algorithms, I see the terms "Path Matrix" and "Transitive Closure" which are not well-defined anywhere.</p>
  
  <p>What does it mean by "Path Matrix" and "Transitive Closure" in case of both Directed and Undirected graphs?</p>