Giansalvatore Mecca Paolo Papotti Salvatore Raunich Marcello Buoncristiano Concise and Expressive Mappings with +Spicy. 1582-1585 2009 2 PVLDB 2 http://www.vldb.org/pvldb/2/vldb09-1000.pdf db/journals/pvldb/pvldb2.html#MeccaPRB09