SPAQRL create exclusion query - sparql

Question

I have this kind of structure
<ontology:Louvre>
<rdf:type ontology:Museum/>
<ontology:preserves rdf:Gioconda/>
<ontology:locatedIn rdf:Paris/>
<ontology:name>Louvre</ontology:name>
<ontology:Gioconda>
<rdf:type ontology:Artwork/>
<ontology:preserved rdf:Louvre/>
<ontology:author rdf:Leonardo/>
<nomeOpera>Gioconda</nomeOpera>
<rdf:Leonardo_Da_Vinci>
<rdf:type ontology:Painter"/>
<ontology:paint ontology:Gioconda"/>
<ontology:paint ontology:Ultima_cena"/>
<name>Leonardo Da Vinci</name>
...(other museum, artist and artwork)
I use "ontology" to indicate my prefix
Is it possible to recover the exclusive artists of a museum?

Answer 1

I found the solution.
This is the query that i'm looking for
SELECT DISTINCT * WHERE {
?museum ontology:preserves ?artwork .
?museum ontology:name "Louvre" .
?artwork ontology:author ?author.
FILTER NOT EXISTS{
?museum2 ontology:preserves ?artwork2 .
?artwork2 ontology:author ?author .
FILTER (?museum2 != ?museum)
}
}