What is the research problem addressed by paper "LIMSI participant at QADL-5@CLEF"?
SELECT ?problem ?problem_lbl
WHERE {
  ?paper orkgp:P31 ?cont;
         rdfs:label ?paper_title.
  ?cont orkgp:P32 ?problem.
  ?problem rdfs:label ?problem_lbl.
  FILTER(REGEX(STR(?paper_title), "LIMSI participation at QALD-5@CLEF", "i"))
}