title: Head-finding rules for noun phrases
body: <p>The Penn Treebank format does not annotate the internal structure of a noun phrase, e.g.</p>
  
  <pre><code>(NP (JJ crude) (NN oil) (NNS prices))
  </code></pre>
  
  <p>or </p>
  
  <pre><code>(NP
      (NP (DT the) (JJ big) (JJ blue) (NN house))
      (SBAR
        (WHNP (WDT that))
        (S
          (VP (VBD was)
            (VP (VBN built)
              (PP (IN near)
                (NP (DT the) (NN river)))))))
  </code></pre>
  
  <p>I would like to extract the heads (prices and house). Do you know of any tool that can do this?</p>