package edu.stanford.nlp.parser.shiftreduce;
import edu.stanford.nlp.util.logging.Redwood;
import java.text.DecimalFormat;
import java.text.NumberFormat;
import java.util.Collection;
import java.util.Collections;
import java.util.Iterator;
import java.util.List;
import java.util.Map;
import java.util.PriorityQueue;
import java.util.Random;
import java.util.Set;
import java.util.regex.Matcher;
import java.util.regex.Pattern;
import edu.stanford.nlp.parser.common.ParserConstraint;
import edu.stanford.nlp.parser.lexparser.EvaluateTreebank;
import edu.stanford.nlp.stats.IntCounter;
import edu.stanford.nlp.tagger.common.Tagger;
import edu.stanford.nlp.trees.Tree;
import edu.stanford.nlp.trees.Treebank;
import edu.stanford.nlp.util.CollectionUtils;
import edu.stanford.nlp.util.Generics;
import edu.stanford.nlp.util.Index;
import edu.stanford.nlp.util.Pair;
import edu.stanford.nlp.util.ReflectionLoading;
import edu.stanford.nlp.util.ScoredComparator;
import edu.stanford.nlp.util.ScoredObject;
import edu.stanford.nlp.util.Timing;
import edu.stanford.nlp.util.Triple;
import edu.stanford.nlp.util.concurrent.MulticoreWrapper;
import edu.stanford.nlp.util.concurrent.ThreadsafeProcessor;
public class PerceptronModel extends BaseModel {
/** A logger for this class */
private static Redwood.RedwoodChannels log = Redwood.channels(PerceptronModel.class); // Serializable
Map<String, Weight> featureWeights;
final FeatureFactory featureFactory;
public PerceptronModel(ShiftReduceOptions op, Index<Transition> transitionIndex,
Set<String> knownStates, Set<String> rootStates, Set<String> rootOnlyStates) {
super(op, transitionIndex, knownStates, rootStates, rootOnlyStates);
this.featureWeights = Generics.newHashMap();
String[] classes = op.featureFactoryClass.split(";");
if (classes.length == 1) {
this.featureFactory = ReflectionLoading.loadByReflection(classes[0]);
} else {
FeatureFactory[] factories = new FeatureFactory[classes.length];
for (int i = 0; i < classes.length; ++i) {
int paren = classes[i].indexOf('(');
if (paren >= 0) {
String arg = classes[i].substring(paren + 1, classes[i].length() - 1);
factories[i] = ReflectionLoading.loadByReflection(classes[i].substring(0, paren), arg);
} else {
factories[i] = ReflectionLoading.loadByReflection(classes[i]);
}
}
this.featureFactory = new CombinationFeatureFactory(factories);
}
}
public PerceptronModel(PerceptronModel other) {
super(other);
this.featureFactory = other.featureFactory;
this.featureWeights = Generics.newHashMap();
for (String feature : other.featureWeights.keySet()) {
featureWeights.put(feature, new Weight(other.featureWeights.get(feature)));
}
}
private static final NumberFormat NF = new DecimalFormat("0.00");
private static final NumberFormat FILENAME = new DecimalFormat("0000");
public void averageScoredModels(Collection<ScoredObject<PerceptronModel>> scoredModels) {
if (scoredModels.isEmpty()) {
throw new IllegalArgumentException("Cannot average empty models");
}
log.info("Averaging " + scoredModels.size() + " models with scores");
for (ScoredObject<PerceptronModel> model : scoredModels) {
log.info(" " + NF.format(model.score()));
}
log.info();
List<PerceptronModel> models = CollectionUtils.transformAsList(scoredModels, ScoredObject::object);
averageModels(models);
}
public void averageModels(Collection<PerceptronModel> models) {
if (models.isEmpty()) {
throw new IllegalArgumentException("Cannot average empty models");
}
Set<String> features = Generics.newHashSet();
for (PerceptronModel model : models) {
for (String feature : model.featureWeights.keySet()) {
features.add(feature);
}
}
featureWeights = Generics.newHashMap();
for (String feature : features) {
featureWeights.put(feature, new Weight());
}
int numModels = models.size();
for (String feature : features) {
for (PerceptronModel model : models) {
if (!model.featureWeights.containsKey(feature)) {
continue;
}
featureWeights.get(feature).addScaled(model.featureWeights.get(feature), 1.0f / numModels);
}
}
}
/**
* Iterate over the feature weight map.
* For each feature, remove all transitions with score of 0.
* Any feature with no transitions left is then removed
*/
void condenseFeatures() {
Iterator<String> featureIt = featureWeights.keySet().iterator();
while (featureIt.hasNext()) {
String feature = featureIt.next();
Weight weights = featureWeights.get(feature);
weights.condense();
if (weights.size() == 0) {
featureIt.remove();
}
}
}
void filterFeatures(Set<String> keep) {
Iterator<String> featureIt = featureWeights.keySet().iterator();
while (featureIt.hasNext()) {
if (!keep.contains(featureIt.next())) {
featureIt.remove();
}
}
}
/**
* Output some random facts about the model
*/
public void outputStats() {
log.info("Number of known features: " + featureWeights.size());
int numWeights = 0;
for (Map.Entry<String, Weight> stringWeightEntry : featureWeights.entrySet()) {
numWeights += stringWeightEntry.getValue().size();
}
log.info("Number of non-zero weights: " + numWeights);
int wordLength = 0;
for (String feature : featureWeights.keySet()) {
wordLength += feature.length();
}
log.info("Total word length: " + wordLength);
log.info("Number of transitions: " + transitionIndex.size());
}
/** Reconstruct that tag set that was used to train the model by decoding some of the features.
* This is slow and brittle but should work! Only if "-" is not in the tag set....
*/
@Override
Set<String> tagSet() {
Set<String> tags = Generics.newHashSet();
Pattern p1 = Pattern.compile("Q0TQ1T-([^-]+)-.*");
Pattern p2 = Pattern.compile("S0T-(.*)");
for (String feat : featureWeights.keySet()) {
Matcher m1 = p1.matcher(feat);
if (m1.matches()) {
tags.add(m1.group(1));
}
Matcher m2 = p2.matcher(feat);
if (m2.matches()) {
tags.add(m2.group(1));
}
}
// Add the end of sentence tag!
// The SR model doesn't use it, but other models do and report it.
// todo [cdm 2014]: Maybe we should reverse the convention here?!?
tags.add(Tagger.EOS_TAG);
return tags;
}
/** Convenience method: returns one highest scoring transition, without any ParserConstraints */
private ScoredObject<Integer> findHighestScoringTransition(State state, List<String> features, boolean requireLegal) {
Collection<ScoredObject<Integer>> transitions = findHighestScoringTransitions(state, features, requireLegal, 1, null);
if (transitions.isEmpty()) {
return null;
}
return transitions.iterator().next();
}
@Override
public Collection<ScoredObject<Integer>> findHighestScoringTransitions(State state, boolean requireLegal, int numTransitions, List<ParserConstraint> constraints) {
List<String> features = featureFactory.featurize(state);
return findHighestScoringTransitions(state, features, requireLegal, numTransitions, constraints);
}
private Collection<ScoredObject<Integer>> findHighestScoringTransitions(State state, List<String> features, boolean requireLegal, int numTransitions, List<ParserConstraint> constraints) {
float[] scores = new float[transitionIndex.size()];
for (String feature : features) {
Weight weight = featureWeights.get(feature);
if (weight == null) {
// Features not in our index are ignored
continue;
}
weight.score(scores);
}
PriorityQueue<ScoredObject<Integer>> queue = new PriorityQueue<>(numTransitions + 1, ScoredComparator.ASCENDING_COMPARATOR);
for (int i = 0; i < scores.length; ++i) {
if (!requireLegal || transitionIndex.get(i).isLegal(state, constraints)) {
queue.add(new ScoredObject<>(i, scores[i]));
if (queue.size() > numTransitions) {
queue.poll();
}
}
}
return queue;
}
private static class Update {
final List<String> features;
final int goldTransition;
final int predictedTransition;
final float delta;
Update(List<String> features, int goldTransition, int predictedTransition, float delta) {
this.features = features;
this.goldTransition = goldTransition;
this.predictedTransition = predictedTransition;
this.delta = delta;
}
}
private Pair<Integer, Integer> trainTree(int index, List<Tree> binarizedTrees, List<List<Transition>> transitionLists, List<Update> updates, Oracle oracle) {
int numCorrect = 0;
int numWrong = 0;
Tree tree = binarizedTrees.get(index);
ReorderingOracle reorderer = null;
if (op.trainOptions().trainingMethod == ShiftReduceTrainOptions.TrainingMethod.REORDER_ORACLE ||
op.trainOptions().trainingMethod == ShiftReduceTrainOptions.TrainingMethod.REORDER_BEAM) {
reorderer = new ReorderingOracle(op);
}
// TODO. This training method seems to be working in that it
// trains models just like the gold and early termination methods do.
// However, it causes the feature space to go crazy. Presumably
// leaving out features with low weights or low frequencies would
// significantly help with that. Otherwise, not sure how to keep
// it under control.
if (op.trainOptions().trainingMethod == ShiftReduceTrainOptions.TrainingMethod.ORACLE) {
State state = ShiftReduceParser.initialStateFromGoldTagTree(tree);
while (!state.isFinished()) {
List<String> features = featureFactory.featurize(state);
ScoredObject<Integer> prediction = findHighestScoringTransition(state, features, true);
if (prediction == null) {
throw new AssertionError("Did not find a legal transition");
}
int predictedNum = prediction.object();
Transition predicted = transitionIndex.get(predictedNum);
OracleTransition gold = oracle.goldTransition(index, state);
if (gold.isCorrect(predicted)) {
numCorrect++;
if (gold.transition != null && !gold.transition.equals(predicted)) {
int transitionNum = transitionIndex.indexOf(gold.transition);
if (transitionNum < 0) {
// TODO: do we want to add unary transitions which are
// only possible when the parser has gone off the rails?
continue;
}
updates.add(new Update(features, transitionNum, -1, 1.0f));
}
} else {
numWrong++;
int transitionNum = -1;
if (gold.transition != null) {
transitionNum = transitionIndex.indexOf(gold.transition);
// TODO: this can theoretically result in a -1 gold
// transition if the transition exists, but is a
// CompoundUnaryTransition which only exists because the
// parser is wrong. Do we want to add those transitions?
}
updates.add(new Update(features, transitionNum, predictedNum, 1.0f));
}
state = predicted.apply(state);
}
} else if (op.trainOptions().trainingMethod == ShiftReduceTrainOptions.TrainingMethod.BEAM ||
op.trainOptions().trainingMethod == ShiftReduceTrainOptions.TrainingMethod.REORDER_BEAM) {
if (op.trainOptions().beamSize <= 0) {
throw new IllegalArgumentException("Illegal beam size " + op.trainOptions().beamSize);
}
List<Transition> transitions = Generics.newLinkedList(transitionLists.get(index));
PriorityQueue<State> agenda = new PriorityQueue<>(op.trainOptions().beamSize + 1, ScoredComparator.ASCENDING_COMPARATOR);
State goldState = ShiftReduceParser.initialStateFromGoldTagTree(tree);
agenda.add(goldState);
int transitionCount = 0;
while (transitions.size() > 0) {
Transition goldTransition = transitions.get(0);
Transition highestScoringTransitionFromGoldState = null;
double highestScoreFromGoldState = 0.0;
PriorityQueue<State> newAgenda = new PriorityQueue<>(op.trainOptions().beamSize + 1, ScoredComparator.ASCENDING_COMPARATOR);
State highestScoringState = null;
State highestCurrentState = null;
for (State currentState : agenda) {
boolean isGoldState = (op.trainOptions().trainingMethod == ShiftReduceTrainOptions.TrainingMethod.REORDER_BEAM &&
goldState.areTransitionsEqual(currentState));
List<String> features = featureFactory.featurize(currentState);
Collection<ScoredObject<Integer>> stateTransitions = findHighestScoringTransitions(currentState, features, true, op.trainOptions().beamSize, null);
for (ScoredObject<Integer> transition : stateTransitions) {
State newState = transitionIndex.get(transition.object()).apply(currentState, transition.score());
newAgenda.add(newState);
if (newAgenda.size() > op.trainOptions().beamSize) {
newAgenda.poll();
}
if (highestScoringState == null || highestScoringState.score() < newState.score()) {
highestScoringState = newState;
highestCurrentState = currentState;
}
if (isGoldState &&
(highestScoringTransitionFromGoldState == null || transition.score() > highestScoreFromGoldState)) {
highestScoringTransitionFromGoldState = transitionIndex.get(transition.object());
highestScoreFromGoldState = transition.score();
}
}
}
// This can happen if the REORDER_BEAM method backs itself
// into a corner, such as transitioning to something that
// can't have a FinalizeTransition applied. This doesn't
// happen for the BEAM method because in that case the correct
// state (eg one with ROOT) isn't on the agenda so it stops.
if (op.trainOptions().trainingMethod == ShiftReduceTrainOptions.TrainingMethod.REORDER_BEAM && highestScoringTransitionFromGoldState == null) {
break;
}
State newGoldState = goldTransition.apply(goldState, 0.0);
// if highest scoring state used the correct transition, no training
// otherwise, down the last transition, up the correct
if (!newGoldState.areTransitionsEqual(highestScoringState)) {
++numWrong;
List<String> goldFeatures = featureFactory.featurize(goldState);
int lastTransition = transitionIndex.indexOf(highestScoringState.transitions.peek());
updates.add(new Update(featureFactory.featurize(highestCurrentState), -1, lastTransition, 1.0f));
updates.add(new Update(goldFeatures, transitionIndex.indexOf(goldTransition), -1, 1.0f));
if (op.trainOptions().trainingMethod == ShiftReduceTrainOptions.TrainingMethod.BEAM) {
// If the correct state has fallen off the agenda, break
if (!ShiftReduceUtils.findStateOnAgenda(newAgenda, newGoldState)) {
break;
} else {
transitions.remove(0);
}
} else if (op.trainOptions().trainingMethod == ShiftReduceTrainOptions.TrainingMethod.REORDER_BEAM) {
if (!ShiftReduceUtils.findStateOnAgenda(newAgenda, newGoldState)) {
if (!reorderer.reorder(goldState, highestScoringTransitionFromGoldState, transitions)) {
break;
}
newGoldState = highestScoringTransitionFromGoldState.apply(goldState);
if (!ShiftReduceUtils.findStateOnAgenda(newAgenda, newGoldState)) {
break;
}
} else {
transitions.remove(0);
}
}
} else {
++numCorrect;
transitions.remove(0);
}
goldState = newGoldState;
agenda = newAgenda;
}
} else if (op.trainOptions().trainingMethod == ShiftReduceTrainOptions.TrainingMethod.REORDER_ORACLE ||
op.trainOptions().trainingMethod == ShiftReduceTrainOptions.TrainingMethod.EARLY_TERMINATION ||
op.trainOptions().trainingMethod == ShiftReduceTrainOptions.TrainingMethod.GOLD) {
State state = ShiftReduceParser.initialStateFromGoldTagTree(tree);
List<Transition> transitions = transitionLists.get(index);
transitions = Generics.newLinkedList(transitions);
boolean keepGoing = true;
while (transitions.size() > 0 && keepGoing) {
Transition transition = transitions.get(0);
int transitionNum = transitionIndex.indexOf(transition);
List<String> features = featureFactory.featurize(state);
int predictedNum = findHighestScoringTransition(state, features, false).object();
Transition predicted = transitionIndex.get(predictedNum);
if (transitionNum == predictedNum) {
transitions.remove(0);
state = transition.apply(state);
numCorrect++;
} else {
numWrong++;
// TODO: allow weighted features, weighted training, etc
updates.add(new Update(features, transitionNum, predictedNum, 1.0f));
switch (op.trainOptions().trainingMethod) {
case EARLY_TERMINATION:
keepGoing = false;
break;
case GOLD:
transitions.remove(0);
state = transition.apply(state);
break;
case REORDER_ORACLE:
keepGoing = reorderer.reorder(state, predicted, transitions);
if (keepGoing) {
state = predicted.apply(state);
}
break;
default:
throw new IllegalArgumentException("Unexpected method " + op.trainOptions().trainingMethod);
}
}
}
}
return Pair.makePair(numCorrect, numWrong);
}
private class TrainTreeProcessor implements ThreadsafeProcessor<Integer, Pair<Integer, Integer>> {
List<Tree> binarizedTrees;
List<List<Transition>> transitionLists;
List<Update> updates; // this needs to be a synchronized list
Oracle oracle;
public TrainTreeProcessor(List<Tree> binarizedTrees, List<List<Transition>> transitionLists, List<Update> updates, Oracle oracle) {
this.binarizedTrees = binarizedTrees;
this.transitionLists = transitionLists;
this.updates = updates;
this.oracle = oracle;
}
public Pair<Integer, Integer> process(Integer index) {
return trainTree(index, binarizedTrees, transitionLists, updates, oracle);
}
public TrainTreeProcessor newInstance() {
// already threadsafe
return this;
}
}
/**
* Trains a batch of trees and returns the following: a list of
* Update objects, the number of transitions correct, and the number
* of transitions wrong.
* <br>
* If the model is trained with multiple threads, it is expected
* that a valid MulticoreWrapper is passed in which does the
* processing. In that case, the processing is done on all of the
* trees without updating any weights, which allows the results for
* multithreaded training to be reproduced.
*/
private Triple<List<Update>, Integer, Integer> trainBatch(List<Integer> indices, List<Tree> binarizedTrees, List<List<Transition>> transitionLists, List<Update> updates, Oracle oracle, MulticoreWrapper<Integer, Pair<Integer, Integer>> wrapper) {
int numCorrect = 0;
int numWrong = 0;
if (op.trainOptions.trainingThreads == 1) {
for (Integer index : indices) {
Pair<Integer, Integer> count = trainTree(index, binarizedTrees, transitionLists, updates, oracle);
numCorrect += count.first;
numWrong += count.second;
}
} else {
for (Integer index : indices) {
wrapper.put(index);
}
wrapper.join(false);
while (wrapper.peek()) {
Pair<Integer, Integer> result = wrapper.poll();
numCorrect += result.first;
numWrong += result.second;
}
}
return new Triple<>(updates, numCorrect, numWrong);
}
private void trainModel(String serializedPath, Tagger tagger, Random random, List<Tree> binarizedTrees, List<List<Transition>> transitionLists, Treebank devTreebank, int nThreads, Set<String> allowedFeatures) {
double bestScore = 0.0;
int bestIteration = 0;
PriorityQueue<ScoredObject<PerceptronModel>> bestModels = null;
if (op.trainOptions().averagedModels > 0) {
bestModels = new PriorityQueue<>(op.trainOptions().averagedModels + 1, ScoredComparator.ASCENDING_COMPARATOR);
}
List<Integer> indices = Generics.newArrayList();
for (int i = 0; i < binarizedTrees.size(); ++i) {
indices.add(i);
}
Oracle oracle = null;
if (op.trainOptions().trainingMethod == ShiftReduceTrainOptions.TrainingMethod.ORACLE) {
oracle = new Oracle(binarizedTrees, op.compoundUnaries, rootStates);
}
List<Update> updates = Generics.newArrayList();
MulticoreWrapper<Integer, Pair<Integer, Integer>> wrapper = null;
if (nThreads != 1) {
updates = Collections.synchronizedList(updates);
wrapper = new MulticoreWrapper<>(op.trainOptions.trainingThreads, new TrainTreeProcessor(binarizedTrees, transitionLists, updates, oracle));
}
IntCounter<String> featureFrequencies = null;
if (op.trainOptions().featureFrequencyCutoff > 1) {
featureFrequencies = new IntCounter<>();
}
for (int iteration = 1; iteration <= op.trainOptions.trainingIterations; ++iteration) {
Timing trainingTimer = new Timing();
int numCorrect = 0;
int numWrong = 0;
Collections.shuffle(indices, random);
for (int start = 0; start < indices.size(); start += op.trainOptions.batchSize) {
int end = Math.min(start + op.trainOptions.batchSize, indices.size());
Triple<List<Update>, Integer, Integer> result = trainBatch(indices.subList(start, end), binarizedTrees, transitionLists, updates, oracle, wrapper);
numCorrect += result.second;
numWrong += result.third;
for (Update update : result.first) {
for (String feature : update.features) {
if (allowedFeatures != null && !allowedFeatures.contains(feature)) {
continue;
}
Weight weights = featureWeights.get(feature);
if (weights == null) {
weights = new Weight();
featureWeights.put(feature, weights);
}
weights.updateWeight(update.goldTransition, update.delta);
weights.updateWeight(update.predictedTransition, -update.delta);
if (featureFrequencies != null) {
featureFrequencies.incrementCount(feature, (update.goldTransition >= 0 && update.predictedTransition >= 0) ? 2 : 1);
}
}
}
updates.clear();
}
trainingTimer.done("Iteration " + iteration);
log.info("While training, got " + numCorrect + " transitions correct and " + numWrong + " transitions wrong");
outputStats();
double labelF1 = 0.0;
if (devTreebank != null) {
EvaluateTreebank evaluator = new EvaluateTreebank(op, null, new ShiftReduceParser(op, this), tagger);
evaluator.testOnTreebank(devTreebank);
labelF1 = evaluator.getLBScore();
log.info("Label F1 after " + iteration + " iterations: " + labelF1);
if (labelF1 > bestScore) {
log.info("New best dev score (previous best " + bestScore + ")");
bestScore = labelF1;
bestIteration = iteration;
} else {
log.info("Failed to improve for " + (iteration - bestIteration) + " iteration(s) on previous best score of " + bestScore);
if (op.trainOptions.stalledIterationLimit > 0 && (iteration - bestIteration >= op.trainOptions.stalledIterationLimit)) {
log.info("Failed to improve for too long, stopping training");
break;
}
}
log.info();
if (bestModels != null) {
bestModels.add(new ScoredObject<>(new PerceptronModel(this), labelF1));
if (bestModels.size() > op.trainOptions().averagedModels) {
bestModels.poll();
}
}
}
if (op.trainOptions().saveIntermediateModels && serializedPath != null && op.trainOptions.debugOutputFrequency > 0) {
String tempName = serializedPath.substring(0, serializedPath.length() - 7) + "-" + FILENAME.format(iteration) + "-" + NF.format(labelF1) + ".ser.gz";
ShiftReduceParser temp = new ShiftReduceParser(op, this);
temp.saveModel(tempName);
// TODO: we could save a cutoff version of the model,
// especially if we also get a dev set number for it, but that
// might be overkill
}
}
if (wrapper != null) {
wrapper.join();
}
if (bestModels != null) {
if (op.trainOptions().cvAveragedModels && devTreebank != null) {
List<ScoredObject<PerceptronModel>> models = Generics.newArrayList();
while (bestModels.size() > 0) {
models.add(bestModels.poll());
}
Collections.reverse(models);
double bestF1 = 0.0;
int bestSize = 0;
for (int i = 1; i <= models.size(); ++i) {
log.info("Testing with " + i + " models averaged together");
// TODO: this is kind of ugly, would prefer a separate object
averageScoredModels(models.subList(0, i));
ShiftReduceParser temp = new ShiftReduceParser(op, this);
EvaluateTreebank evaluator = new EvaluateTreebank(temp.getOp(), null, temp, tagger);
evaluator.testOnTreebank(devTreebank);
double labelF1 = evaluator.getLBScore();
log.info("Label F1 for " + i + " models: " + labelF1);
if (labelF1 > bestF1) {
bestF1 = labelF1;
bestSize = i;
}
}
averageScoredModels(models.subList(0, bestSize));
} else {
averageScoredModels(bestModels);
}
}
// TODO: perhaps we should filter the features and then get dev
// set scores. That way we can merge the models which are best
// after filtering.
if (featureFrequencies != null) {
filterFeatures(featureFrequencies.keysAbove(op.trainOptions().featureFrequencyCutoff));
}
condenseFeatures();
}
/**
* Will train the model on the given treebank, using devTreebank as
* a dev set. If op.retrainAfterCutoff is set, will rerun training
* after the first time through on a limited set of features.
*/
public void trainModel(String serializedPath, Tagger tagger, Random random, List<Tree> binarizedTrees, List<List<Transition>> transitionLists, Treebank devTreebank, int nThreads) {
if (op.trainOptions().retrainAfterCutoff && op.trainOptions().featureFrequencyCutoff > 0) {
String tempName = serializedPath.substring(0, serializedPath.length() - 7) + "-" + "temp.ser.gz";
trainModel(tempName, tagger, random, binarizedTrees, transitionLists, devTreebank, nThreads, null);
ShiftReduceParser temp = new ShiftReduceParser(op, this);
temp.saveModel(tempName);
Set<String> features = featureWeights.keySet();
featureWeights = Generics.newHashMap();
trainModel(serializedPath, tagger, random, binarizedTrees, transitionLists, devTreebank, nThreads, features);
} else {
trainModel(serializedPath, tagger, random, binarizedTrees, transitionLists, devTreebank, nThreads, null);
}
}
private static final long serialVersionUID = 1;
}