title: SPARQL regex filter
body: <p>I'm trying to match one word in SPARQL by using regex filter, but without success... :/
  I'm sending the query to the endpoint located at "http://dbtune.org/musicbrainz/sparql".
  Well, the following query works:</p>
  
  <pre><code>PREFIX foaf: &lt;http://xmlns.com/foaf/0.1/&gt;
  PREFIX rdf: &lt;http://www.w3.org/1999/02/22-rdf-syntax-ns#&gt;
  PREFIX mo: &lt;http://purl.org/ontology/mo/&gt;
  SELECT ?artist ?name
  WHERE {
      ?artist a mo:MusicArtist
      . ?artist foaf:name "Switchfoot"
      . ?artist foaf:name ?name
      . FILTER(regex(str(?name), "switchfoot", "i"))
  }
  </code></pre>
  
  <p>But, if I remove the line 7 (. ?artist foaf:name "Switchfoot"), the following query does not match:</p>
  
  <pre><code>PREFIX foaf: &lt;http://xmlns.com/foaf/0.1/&gt;
  PREFIX rdf: &lt;http://www.w3.org/1999/02/22-rdf-syntax-ns#&gt;
  PREFIX mo: &lt;http://purl.org/ontology/mo/&gt;
  SELECT ?artist ?name
  WHERE {
      ?artist a mo:MusicArtist
      . ?artist foaf:name ?name
      . FILTER(regex(str(?name), "switchfoot", "i"))
  }
  </code></pre>
  
  <p>I don't know if I am doing something wrongly or it's a bug of endpoint...</p>
  
  <p>Can somebody help me?</p>