org.egothor.stemmer
Class Lift

java.lang.Object
  org.egothor.stemmer.Reduce
      org.egothor.stemmer.Lift

public class Lift

extends Reduce

The Lift class is adata structure that is a variation of a Patricia trie. Lift's raison d'etre is to implement reduction of the trie via the Lift-Up method., which makes the data structure less liable to overstemming.

Author:

Leo Galambos

Constructor Summary

Lift(boolean changeSkip)
Constructor for the Lift object.

Method Summary

void	liftUp(Row in, java.util.Vector nodes) Reduce the trie using Lift-Up reduction.
Trie	optimize(Trie orig) Optimize (eliminate rows with no content) the given Trie and return the reduced Trie.

Methods inherited from class java.lang.Object

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

Constructor Detail

Lift

public Lift(boolean changeSkip)

Constructor for the Lift object.

Parameters:

changeSkip - when set to true , comparison of two Cells takes a skip command into account

Method Detail

optimize

public Trie optimize(Trie orig)

Optimize (eliminate rows with no content) the given Trie and return the reduced Trie.

Overrides:

optimize in class Reduce

Parameters:

orig - the Trie to optimized

Returns:

the reduced Trie

liftUp

public void liftUp(Row in,
                   java.util.Vector nodes)

Reduce the trie using Lift-Up reduction. The Lift-Up reduction propagates all leaf-values (patch commands), where possible, to higher levels which are closer to the root of the trie.

Parameters:

in - the Row to consider when optimizing

nodes - contains the patch commands