import "/std/ns.rql";
import "/std/rdfs.rql";

session.namespaces["ex"] =
"http://www.aifb.uni-karlsruhe.de/WBS/pha/rdf-query/sample.rdf#";
session.namespaces["top"] =
"http://daml.umbc.edu/ontologies/topic-ont#";

var url =
"http://www.aifb.uni-karlsruhe.de/WBS/pha/rdf-query/queries/sample.rdf";

var ds = new datasource();
ds.insert(new datasource("inet?parsetype=rdf&url=" + server.urlencode(url), session.namespaces["ex"]));


//6.Count the number of authors of a publication.
select ?cnt using #ds rulebase rdfs where {[rdf:type] ?s [ex:Publication]} 
		and {[ex:author] ?s ?l} 
		and {?li ?l ?i} 
		and {[ex:name] ?i ?n}
		and groupby(?s) (?cnt=count(?n));