title: How to order graph's nodes such that the distance between two adjacent nodes is minimal
body: <p>I was wondering if this problem is known in graph theory:
  I have an undirected graph with no weights G=(V,A) and I want to place the nodes of this graph in a string so that directed nodes are placed as much close as possible. So for example:</p>
  
  <p>Given  this graph:</p>
  
  <pre><code>a,b;a,d;b,e;c,f;c,h;f,h;e,g;e,h.
  </code></pre>
  
  <p>where arcs are separated by ';' </p>
  
  <p>I need to get to this solution:
  a,b,d,e,g,h,c,f=2
  where 2 is the maximum distance in the string a,b,d,e,g,h,c,f between two directed nodes.</p>
  
  <p><strong>Formally:</strong></p>
  
  <ul>
  <li>let d(v,u) be the distance between two nodes according to the graph.</li>
  <li>Find an order v<sub>1,</sub>,v<sub>2,</sub>,v<sub>n,</sub>, such that max{d(v<sub>i,</sub>,v<sub>i+1,</sub>) } is minimal</li>
  </ul>