Question: List the common prime minister of the Robert Ray and graham richardson ?
SPARQL query: SELECT DISTINCT ?uri WHERE { <http://dbpedia.org/resource/Robert_Ray_(Australian_politician)> <http://dbpedia.org/ontology/primeMinister> ?uri. <http://dbpedia.org/resource/Graham_Richardson> <http://dbpedia.org/ontology/primeMinister> ?uri . }
Answer: The prime ministers of both Robert Ray and Graham Richardson are [Bob Hawke, Paul Keating].