query: #title: Strange P31 link between parents in P279
  # Complex constraint from [[Property talk:P31]]
  #
  SELECT ?item (count(*) as ?count) WHERE {
      ?classC wdt:P279 ?item;
              wdt:P279 ?classB .
      ?classB wdt:P31 ?item.
  } 
  GROUP BY ?item
  ORDER BY DESC(?count)