edu.stanford.nlp.trees
Class SemanticHeadFinder

java.lang.Object
  edu.stanford.nlp.trees.AbstractCollinsHeadFinder
      edu.stanford.nlp.trees.CollinsHeadFinder
          edu.stanford.nlp.trees.ModCollinsHeadFinder
              edu.stanford.nlp.trees.SemanticHeadFinder

All Implemented Interfaces:

HeadFinder, Serializable

public class SemanticHeadFinder
extends ModCollinsHeadFinder

Implements a 'semantic head' variant of the the HeadFinder found in Michael Collins' 1999 thesis. This version chooses the semantic head verb rather than the verb form for cases with verbs. Should remember auxiliaries to differentiate past and passive, though. Except: we've added a head rule for NX (returns rightmost), whereas no rule for the head of NX is found in any of the versions of Collins' head table that we have (did he perhaps use the NP rules for NX?

Author:

John Rappaport

See Also:

Serialized Form

Field Summary

Fields inherited from class edu.stanford.nlp.trees.AbstractCollinsHeadFinder

defaultRule, nonTerminalInfo, tlp

Constructor Summary

SemanticHeadFinder()

SemanticHeadFinder(TreebankLanguagePack tlp)

Method Summary

protected Tree

determineNonTrivialHead(Tree t) Determine which daughter of the current parse tree is the head.

Methods inherited from class edu.stanford.nlp.trees.CollinsHeadFinder

main, postOperationFix

Methods inherited from class edu.stanford.nlp.trees.AbstractCollinsHeadFinder

determineHead, findMarkedHead, traverseLocate

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

SemanticHeadFinder

public SemanticHeadFinder()

SemanticHeadFinder

public SemanticHeadFinder(TreebankLanguagePack tlp)

Method Detail

determineNonTrivialHead

protected Tree determineNonTrivialHead(Tree t)

Determine which daughter of the current parse tree is the head. It assumes that the daughters alread have had their heads determined. Uses special rule for VPheads

Overrides:

determineNonTrivialHead in class AbstractCollinsHeadFinder

Parameters:

t - The parse tree to examine the daughters of. This is assumed to never be a leaf

Returns:

The parse tree that is the head