Question: What is the highest mountain?
SPARQL:
PREFIX rdfs: <http://www.w3.org/2000/01/rdf-schema#>
PREFIX onto: <http://dbpedia.org/ontology/>
PREFIX rdf: <http://www.w3.org/1999/02/22-rdf-syntax-ns#>
SELECT ?uri ?string
WHERE
{ 
	?uri  rdf:type onto:Mountain  .
        ?uri onto:elevation ?elevation .
        OPTIONAL {?uri rdfs:label ?string . FILTER (lang(?string) = 'en') }
} ORDER BY DESC(?elevation) LIMIT 1