title: How to make an edge with both direction in GraphViz?
body: <p>How to make an edge with both direction in GraphViz?</p>
  
  <p>I am trying to make an curved edge with both direction.</p>
  
  <p>But the only plot I can make is:</p>
  
  <p><a href="https://i.stack.imgur.com/By576.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/By576.png" alt="enter image description here"></a></p>
  
  <p>I want to make the edge between x1 and x2 curved with both direction.</p>
  
  <p>The code I used:</p>
  
  <pre><code>digraph {
  
  rankdir=LR
  
  node [shape=box ]
  x1;x2
  node [shape=oval ]
  y
  
  x1-&gt;y[dir=back label=0.77]
  x2-&gt;y[dir=back label=0.42]
  
  x1:w -&gt; x2:w[dir=both constraint=false]
  
  }
  </code></pre>
  
  <p>I would appreciate any help.</p>