title: semantic web request result difference
body: <pre><code>PREFIX dbo: &lt;http://dbpedia.org/ontology/&gt;
  
      SELECT * WHERE {
       ?x foaf:primaryTopic ?n .
       ?x rdf:type ?z .
  
      FILTER (regex(?x, '^http://en.wikipedia.org/wiki/Barack_Obama$')).
  }
  LIMIT 10    
  </code></pre>
  
  <p>when i call this request from <a href="http://dbpedia.org/snorql" rel="nofollow">http://dbpedia.org/snorql</a>, it works. but when i try below </p>
  
  <pre><code>SELECT * WHERE {
   ?x foaf:primaryTopic ?n .
   ?x rdf:type ?z .
   ?x owl:activeYearsStartDate ?v .
   FILTER (regex(?x, '^http://en.wikipedia.org/wiki/Barack_Obama$')).
  }    
  </code></pre>
  
  <p>it doesn't work. but why? </p>