edu.stanford.nlp.trees
Interface HeadFinder

All Superinterfaces:

java.io.Serializable

All Known Implementing Classes:

AbstractCollinsHeadFinder, BikelChineseHeadFinder, ChineseHeadFinder, ChineseSemanticHeadFinder, CollinsHeadFinder, LeftHeadFinder, ModCollinsHeadFinder, SemanticHeadFinder, SunJurafskyChineseHeadFinder

public interface HeadFinder
extends java.io.Serializable

An interface for finding the "head" daughter of a phrase structure tree. This could potentially be any sense of "head", but has mainly been used to find the lexical head for lexicalized PCFG parsing.

Author:

Christopher Manning

Method Summary

Tree	determineHead(Tree t) Determine which daughter of the current parse tree is the head.
Tree	determineHead(Tree t, Tree parent) Determine which daughter of the current parse tree is the head given the parent of the tree.

Method Detail

determineHead

Tree determineHead(Tree t)

Determine which daughter of the current parse tree is the head.

Parameters:

t - The parse tree to examine the daughters of

Returns:

The daughter tree that is the head. This will always be non-null. An Exception will be thrown if no head can be determined.

Throws:

java.lang.IllegalStateException - If a subclass has missing or badly formatted head rule data

java.lang.IllegalArgumentException - If the argument Tree has unexpected phrasal categories in it (and the implementation doesn't just use some heuristic to always determine some head).

determineHead

Tree determineHead(Tree t,
                   Tree parent)

Determine which daughter of the current parse tree is the head given the parent of the tree.

Parameters:

t - The parse tree to examine the daughters of

parent - The parent of tree t

Returns:

The daughter tree that is the head. This will always be non-null. An Exception will be thrown if no head can be determined.