query: #title: Error in start or end date
  # Complex constraint from [[Property talk:P2632]]
  # Negative interval between end date and start date
  SELECT DISTINCT ?item
  WHERE { 
    ?item p:P2632 ?statement.
    ?statement pq:P580 ?start.
    ?statement pq:P582 ?end.
    BIND( year(?end)-year(?start) as ?diff ).
    FILTER (?diff < 0)
  }