What is the {palace} for {commissioned by} of {William the Conqueror}
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What palace did William the Conqueror commission?
SELECT DISTINCT ?n WHERE { ?n rdf:type ontology:palace . ?n property:commissioned_by resource:William_the_Conqueror }
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/P88> . ?statement <http://www.w3.org/1999/02/22-rdf-syntax-ns#object> <http://wikidata.dbpedia.org/resource/Q37594> . ?subj <http://www.wikidata.org/entity/P31> <http://wikidata.dbpedia.org/resource/Q16560> } 
 select distinct ?sbj where { ?sbj wdt:P88 wd:Q37594 . ?sbj wdt:P31 wd:Q16560 } 
Windsor Castle