# AGPrologFunctorQminus.java

`package com.franz.agbase.examples;
import com.franz.agbase.*;
public class AGPrologFunctorQminus {
/**
* Demonstrates some basics of using functor q- in PrologSelect queries.
*
* @param unused
* @throws AllegroGraphException
*/
public static void main(String[] args) throws AllegroGraphException {
// Connect to server, which must already be running.
AllegroGraphConnection ags = new AllegroGraphConnection();
try {
ags.enable();
} catch (Exception e) {
throw new AllegroGraphException("Server connection problem", e);
}
// Create a fresh triple-store for this example.
AllegroGraph ts = ags.renew("functorqminus", AGPaths.TRIPLE_STORES);
// Register your namespaces
ts.registerNamespace("ex","http://example.org/");
// Add some triples to the store
ts.addStatement("!ex:a","!ex:owned-by","!ex:b");
ts.addStatement("!ex:c","!ex:owns","!ex:d");
ts.addStatement("!ex:jans","!ex:owns","!ex:birra");
ts.addStatement("!ex:owned-by","!owl:inverseOf","!ex:owns");
// index the store
ts.indexAllTriples();
// Set up a Prolog query object that does RDFS++ reasoning
// over the store
PrologSelectQuery q = new PrologSelectQuery();
q.setTripleStore(ts);
q.setIncludeInferred(true);
// First a query with the q functor. This will include inferred
// results because the includeInferred setting is true.
String[] vars = new String[]{"x","y"};
String pquery = "(q ?x !ex:owns ?y)";
q.setVariables(vars);
q.setQuery(pquery);
ValueSetIterator it = q.run();
System.out.println("Results for " + pquery);
AGUtils.showResults(it);
// Now a query with the q- functor. This returns results that don't
// involve reasoner, overriding any "includeInferred" setting on the
// the query (but just for this clause). It allows disabling of
// reasoning on a clause-by-clause basis for queries involving
// multiple clauses.
pquery = "(q- ?x !ex:owns ?y)";
q.setVariables(vars);
q.setQuery(pquery);
it = q.run();
System.out.println("Results for " + pquery);
AGUtils.showResults(it);
// Add some more triples to the store
ts.addStatement("!ex:A","!rdfs:subClassOf", "!ex:B");
ts.addStatement("!ex:B","!rdfs:subClassOf", "!ex:C");
ts.addStatement("!ex:a","!rdf:type", "!ex:A");
// index again
ts.indexAllTriples();
// Another query without reasoning using functor q-
pquery = "(q- ?x !rdf:type ?y)";
q.setVariables(vars);
q.setQuery(pquery);
it = q.run();
System.out.println("Results for " + pquery);
AGUtils.showResults(it);
// Now demonstrate reasoning with functor q
pquery = "(q ?x !rdf:type ?y)";
q.setVariables(vars);
q.setQuery(pquery);
it = q.run();
System.out.println("Results for " + pquery);
AGUtils.showResults(it);
// Close the triple store and disconnect from the server.
ts.closeTripleStore();
ags.disable();
}
}
`

Up | Next