What is the {library} for {country} of {Roman Empire}
Which country had the Roman Empire library?
Which country contained the library of the Roman Empire?
SELECT DISTINCT ?y WHERE { ?y property:country resource:Roman_Empire . ?y rdf:type ontology:library }
select distinct ?subj where { ?statement <http://www.w3.org/1999/02/22-rdf-syntax-ns#subject> ?subj . ?statement <http://www.w3.org/1999/02/22-rdf-syntax-ns#predicate> <http://www.wikidata.org/entity/P17> . ?statement <http://www.w3.org/1999/02/22-rdf-syntax-ns#object> <http://wikidata.dbpedia.org/resource/Q2277> . ?subj <http://www.wikidata.org/entity/P31> <http://wikidata.dbpedia.org/resource/Q7075> } 
 select distinct ?sbj where { ?sbj wdt:P17 wd:Q2277 . ?sbj wdt:P31 wd:Q7075 } 