Project(Extend(Extend(AggregationJoin(Aggregation(??agg1: ?p, SAMPLE,
                                                  {},
                                                  G1=Group((?p),
                                                     BGP( ?s <http://www.w3.org/1999/02/22-rdf-syntax-ns#type> <http://www.w3.org/2004/02/skos/core#Concept> .
                                                      ?s ?p ?o .
                                                      ?o <http://www.w3.org/1999/02/22-rdf-syntax-ns#type> <http://www.w3.org/2004/02/skos/core#Concept>))),
                                      Aggregation(??agg2: ?p, COUNT, {}, G1)),
                      ?p,
                      ??agg1),
               ?count,
               ??agg2),
        {?p, ?count})