Are there any research problems with benchmark datasets in the realm of Natural Language Processing research?
SELECT DISTINCT ?problem ?problem_lbl
WHERE {
  ?rf       a            orkgc:ResearchField;
            rdfs:label   ?rf_label.
  FILTER (str(?rf_label) = "Natural Language Processing")
  ?paper    orkgp:P30    ?rf;
            orkgp:P31    ?cont.
  ?cont         orkgp:HAS_BENCHMARK      ?benchmark;
                orkgp:P32                ?problem.
  ?problem      rdfs:label               ?problem_lbl.
}