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();
    }

}

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