What are the metrics used by paper "Using NMF-based text summarization to improve supervised and unsupervised classification?
SELECT ?metrics, ?metrics_labels
WHERE {
  ?papers rdfs:label ?title.
  FILTER(REGEX(?title, "NMF-based text summarization"))
  ?papers orkgp:P31 ?cont.
  ?cont orkgp:P34 ?eval.
  ?eval orkgp:P2006 ?metrics.
  ?metrics rdfs:label ?metrics_labels.
}