Project(Extend(Extend(AggregationJoin(Aggregation(??agg1: ?entity, SAMPLE,
                                                  {},
                                                  G1=Group((?entity),
                                                     BGP( ?entity <http://myschema/name> 'J' .
                                                      ?entity <http://myschema/age> ?age))),
                                      Aggregation(??agg2: ?age, MAX, {}, G1)),
                      ?entity,
                      ??agg1),
               ?value,
               ??agg2),
        {?entity, ?value})