What is the {material} with the {MAX(hardness)} whose {use} is {fastener}  ?
What is the hardest material that is used as a fastener?
What is the material with Max hardness which is used as Fastener?
SELECT ?b WHERE { ?b rdf:type ontology:material . ?b property:use resource:fastener . ?b property:hardness ?c }
select ?ent where {
?ent <http://www.wikidata.org/entity/P31> <http://wikidata.dbpedia.org/resource/Q214609>.

?statement1 <http://www.w3.org/1999/02/22-rdf-syntax-ns#subject> ?ent .
?statement1 <http://www.w3.org/1999/02/22-rdf-syntax-ns#predicate> <http://www.wikidata.org/entity/P5483>.
?statement1 <http://www.w3.org/1999/02/22-rdf-syntax-ns#object> ?obj1.

?statement2 <http://www.w3.org/1999/02/22-rdf-syntax-ns#subject> ?ent .
?statement2 <http://www.w3.org/1999/02/22-rdf-syntax-ns#predicate> <http://www.wikidata.org/entity/P366> .
?statement2 <http://www.w3.org/1999/02/22-rdf-syntax-ns#object> <http://wikidata.dbpedia.org/resource/Q2002016> .

}
ORDER BY DESC(?obj1)
LIMIT 5
select ?ent where { ?ent wdt:P31 wd:Q214609 . ?ent wdt:P5483 ?obj . ?ent wdt:P366 wd:Q2002016 } ORDER BY DESC(?obj)LIMIT 5 