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!

Constructor Summary

Constructors

Constructor and 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 and 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

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

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)