What is the {royal or noble rank} for {office held by head of state} of {Roman Empire}
What was the illustrious of the respectable rank of the head of state within the Roman Empire?
What was the royal of the noble rank of the head of state in the Roman Empire?
SELECT DISTINCT ?c WHERE { resource:Roman_Empire property:office_held_by_head_of_state ?c . ?c rdf:type ontology:noble_title }
select distinct ?obj where { ?statement <http://www.w3.org/1999/02/22-rdf-syntax-ns#subject> <http://wikidata.dbpedia.org/resource/Q2277> . ?statement <http://www.w3.org/1999/02/22-rdf-syntax-ns#predicate> <http://www.wikidata.org/entity/P1906> . ?statement <http://www.w3.org/1999/02/22-rdf-syntax-ns#object> ?obj . ?obj <http://www.wikidata.org/entity/P31> <http://wikidata.dbpedia.org/resource/Q355567> } 
 select distinct ?obj where { wd:Q2277 wdt:P1906 ?obj . ?obj wdt:P31 wd:Q355567 } 
Roman emperor