title: Regex: Determine if two regular expressions could match for the same input?
body: <p>I want to find out if there could ever be <em>conflicts</em> between two known regular expressions, in order to allow the user to construct a list of mutually exclusive regular expressions.</p>
  
  <p>For example, we know that the regular expressions below are quite different but they both match <code>xy50</code>:</p>
  
  <pre><code>'^xy1\d'
  '[^\d]\d2$'
  </code></pre>
  
  <p>Is it possible to determine, using a computer algorithm, if two regular expressions can have such a <em>conflict</em>? How?</p>