title: LIKE-operator in relational algebra
body: <p>Is there a way to display a sql LIKE-operator in relational algebra?</p>
  
  <p>right now I have done it like this:</p>
  
  <blockquote>
    <p>&sigma;<sub>firstname LIKE ('B%')</sub>person</p>
  </blockquote>
  
  <p>But I'm not sure if this is the right way to go.</p>
  
  <p>Thanks in advance for the help.</p>