Package cc.mallet.fst.semi_supervised

Class GELattice

java.lang.Object

cc.mallet.fst.semi_supervised.GELattice

public class GELattice
extends java.lang.Object

Runs the dynamic programming algorithm of [Mann and McCallum 08] for computing the gradient of a Generalized Expectation constraint that considers a single label of a linear chain CRF. See: "Generalized Expectation Criteria for Semi-Supervised Learning of Conditional Random Fields" Gideon Mann and Andrew McCallum ACL 2008 gdruck NOTE: This new version of GE Lattice that computes the gradient for all constraints simultaneously!

Author:

Gregory Druck, Gaurav Chandalia, Gideon Mann

Nested Class Summary

Nested Classes

Modifier and Type	Class	Description
protected class	GELattice.LatticeNode	Contains forward-backward vectors correspoding to an input position and a state index.

Field Summary

Fields

Modifier and Type	Field	Description
protected LogNumber[][][]	dotCache
protected GELattice.LatticeNode[][]	lattice
protected int	latticeLength
protected int	numStates
protected Transducer	transducer

Constructor Summary

Constructors

Constructor	Description
GELattice(FeatureVectorSequence fvs, double[][] gammas, double[][][] xis, Transducer transducer, int[][] reverseTrans, int[][] reverseTransIndices, CRF.Factors gradient, java.util.ArrayList<GEConstraint> constraints, boolean check)

Method Summary

Modifier and Type	Method	Description
void	check(java.util.ArrayList<GEConstraint> constraints, double[][] gammas, double[][][] xis, FeatureVectorSequence fvs)	Verifies the correctness of the lattice computations.
LogNumber	getAlpha(int ip, int s1, int s2)
LogNumber	getBeta(int ip, int s1, int s2)

Methods inherited from class java.lang.Object

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

Field Detail

latticeLength

protected int latticeLength

transducer

protected Transducer transducer

numStates

protected int numStates

lattice

protected GELattice.LatticeNode[][] lattice

dotCache

protected LogNumber[][][] dotCache

Constructor Detail

GELattice

public GELattice(FeatureVectorSequence fvs,
                 double[][] gammas,
                 double[][][] xis,
                 Transducer transducer,
                 int[][] reverseTrans,
                 int[][] reverseTransIndices,
                 CRF.Factors gradient,
                 java.util.ArrayList<GEConstraint> constraints,
                 boolean check)

Parameters:

fvs - Input FeatureVectorSequence

gammas - Marginals over single states

xis - Marginals over pairs of states

transducer - Transducer

reverseTrans - Source state indices for each destination state

reverseTransIndices - Transition indices for each destination state

gradient - Gradient to increment

constraints - List of constraints

check - Whether to run the debugging test to verify correctness (will be much slower if true)

Method Detail

check

public void check(java.util.ArrayList<GEConstraint> constraints,
                  double[][] gammas,
                  double[][][] xis,
                  FeatureVectorSequence fvs)

Verifies the correctness of the lattice computations.

getAlpha

public LogNumber getAlpha(int ip,
                          int s1,
                          int s2)

getBeta

public LogNumber getBeta(int ip,
                         int s1,
                         int s2)