machine_question: what is the name of the the sports team arena stadium is Three Rivers Stadium head coach
question: Who is the head coach of the sports team that plays at Three Rivers Stadium?
sparql: PREFIX ns: <http://rdf.freebase.com/ns/>
  SELECT DISTINCT ?x
  WHERE {
  FILTER (?x != ?c)
  FILTER (!isLiteral(?x) OR lang(?x) = '' OR langMatches(lang(?x), 'en'))
  ?c ns:sports.sports_team.arena_stadium ns:m.037286 . 
  ?c ns:american_football.football_team.current_head_coach ?x .
  }
  
webqsp_question: what is the name of the pittsburgh steelers head coach