title: How to query for the number of distinct tuples using SPARQL 1.1?
body: <p>It seems to be possible to count a single entity using</p>
  
  <pre><code>(COUNT(DISTINCT ?x) as ?count)
  </code></pre>
  
  <p>and for the number of distinct tuples for all variables in the query using </p>
  
  <pre><code>(COUNT(DISTINCT *) as ?count)
  </code></pre>
  
  <p>However, I cannot figure out how to count specific (distinct) tuples. Something like </p>
  
  <pre><code>(COUNT(DISTINCT ?a ?b ?c) as ?count) 
  </code></pre>
  
  <p>does not seem to work. Am I doing it wrong or is this really not allowed in SPARQL 1.1? Or is it supposed to work and just not supported in Sesame 2.6.0 which I am using for testing this? </p>