SPARQL queries for Pizza ontology

i have to use ROWLKit http://www.dis.uniroma1.it/quonto/?q=node/30

(1) can anybody suggest two sparql queries for the Pizza.owl ?

(2) is this qu开发者_如何学运维ery valid ?

PREFIX rdf: <http://www.w3.org/1999/02/22-rdf-syntax-ns#>
PREFIX pizza: <http://www.co-ode.org/ontologies/pizza/pizza.owl#>
SELECT * 
WHERE { ?p rdf:type pizza:Pizza;
           pizza:hasTopping ?t.
        ?t rdf:type pizza:TomatoTopping }

(3) if it is a valid query then: is the response an empty result?

SELECT DISTINCT *
WHERE { 
 ?NombrePizza ?Relacion pizza:MushroomTopping .
 ?Relacion owl:inverseOf pizza:isToppingOf .
 OPTIONAL { 
  ?NombrePizza2 ?Relacion2 pizza:HamTopping .
  ?Relacion2 owl:inverseOf pizza:isToppingOf . 
 }
 FILTER(?NombrePizza2 = ?NombrePizza)
}

(1) can anybody suggest two sparql queries for the Pizza.owl ?

Here are two examples:

SELECT * WHERE { ?s ?p ?o }

and:

SELECT ?class WHERE { ?class  a  owl:Class }

(2) is this query valid ?

Yes.

(3) if it is a valid query then: is the response an empty result?

I assume that you mean "if I query the RDF document that serialises the pizza ontology, is the response an empty result?". The answer is yes.

(2) appears to be a valid query

I don't understand part (3) of your question. (2) cannot be compared to a boolean since it returns a Result Set, if you want a boolean result then you need to use an ASK query. If an ASK query returns true then it means that there are solutions to the query in the data you are querying so it would not be an empty result.