title: How do I know when a precedence graph is representable by COBEGIN-COEND?
body: <p>I'm starting to study concurrent programming.</p>
  
  <p>I know that there are precedence graphs that can't be represented only using COBEGIN-COEND construct (introduced by Dijkstra in 1968).</p>
  
  <p>So...</p>
  
  <p>Is there any algorithm to know when a precedence graph is representable by COBEGIN-COEND ??</p>
  
  <p>Thank you very much,</p>
  
  <p>Pablo.</p>