query: #title: Distinct best value constraint
  # Complex constraint from [[Property talk:P297]]
  # A given value should be used by just one value with best rank (normal rank without another statement in preferred rank or preferred rank)
  SELECT DISTINCT ?item ?item2 ?value 
  {
  	?item wdt:P297 ?value .
  	?item2 wdt:P297 ?value .
  	FILTER( ?item != ?item2 && STR( ?item ) < STR( ?item2 ) ) .
  }