Question: Which locations have more than two caves?
SPARQL:
PREFIX onto: <http://dbpedia.org/ontology/>
PREFIX rdf: <http://www.w3.org/1999/02/22-rdf-syntax-ns#>
PREFIX rdfs: <http://www.w3.org/2000/01/rdf-schema#>
SELECT DISTINCT ?uri ?string
WHERE 
{       
        ?cave rdf:type onto:Cave . 
        ?cave onto:location ?uri .
        OPTIONAL {?uri rdfs:label ?string. FILTER (lang(?string) = 'en') }
} HAVING (count(?cave) > 2)