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Contrastive estimation: Training loglinear models on unlabeled data
 In Proc. of ACL
, 2005
"... Conditional random fields (Lafferty et al., 2001) are quite effective at sequence labeling tasks like shallow parsing (Sha and Pereira, 2003) and namedentity extraction (McCallum and Li, 2003). CRFs are loglinear, allowing the incorporation of arbitrary features into the model. To train on unlabele ..."
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Cited by 115 (14 self)
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Conditional random fields (Lafferty et al., 2001) are quite effective at sequence labeling tasks like shallow parsing (Sha and Pereira, 2003) and namedentity extraction (McCallum and Li, 2003). CRFs are loglinear, allowing the incorporation of arbitrary features into the model. To train on unlabeled data, we require unsupervised estimation methods for loglinear models; few exist. We describe a novel approach, contrastive estimation. We show that the new technique can be intuitively understood as exploiting implicit negative evidence and is computationally efficient. Applied to a sequence labeling problem—POS tagging given a tagging dictionary and unlabeled text—contrastive estimation outperforms EM (with the same feature set), is more robust to degradations of the dictionary, and can largely recover by modeling additional features. 1
Discriminative loglinear grammars with latent variables
 In Proceedings of NIPS 20
, 2008
"... We demonstrate that loglinear grammars with latent variables can be practically trained using discriminative methods. Central to efficient discriminative training is a hierarchical pruning procedure which allows feature expectations to be efficiently approximated in a gradientbased procedure. We c ..."
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Cited by 38 (6 self)
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We demonstrate that loglinear grammars with latent variables can be practically trained using discriminative methods. Central to efficient discriminative training is a hierarchical pruning procedure which allows feature expectations to be efficiently approximated in a gradientbased procedure. We compare L1 and L2 regularization and show that L1 regularization is superior, requiring fewer iterations to converge, and yielding sparser solutions. On fullscale treebank parsing experiments, the discriminative latent models outperform both the comparable generative latent models as well as the discriminative nonlatent baselines. 1
Novel Estimation Methods for Unsupervised Discovery of Latent Structure in Natural Language Text
, 2006
"... This thesis is about estimating probabilistic models to uncover useful hidden structure in data; specifically, we address the problem of discovering syntactic structure in natural language text. We present three new parameter estimation techniques that generalize the standard approach, maximum likel ..."
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Cited by 27 (8 self)
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This thesis is about estimating probabilistic models to uncover useful hidden structure in data; specifically, we address the problem of discovering syntactic structure in natural language text. We present three new parameter estimation techniques that generalize the standard approach, maximum likelihood estimation, in different ways. Contrastive estimation maximizes the conditional probability of the observed data given a “neighborhood” of implicit negative examples. Skewed deterministic annealing locally maximizes likelihood using a cautious parameter search strategy that starts with an easier optimization problem than likelihood, and iteratively moves to harder problems, culminating in likelihood. Structural annealing is similar, but starts with a heavy bias toward simple syntactic structures and gradually relaxes the bias. Our estimation methods do not make use of annotated examples. We consider their performance in both an unsupervised model selection setting, where models trained under different initialization and regularization settings are compared by evaluating the training objective on a small set of unseen, unannotated development data, and supervised model selection, where the most accurate model on the development set (now with annotations)
Guiding unsupervised grammar induction using contrastive estimation
 In Proc. of IJCAI Workshop on Grammatical Inference Applications
, 2005
"... We describe a novel training criterion for probabilistic grammar induction models, contrastive estimation [Smith and Eisner, 2005], which can be interpreted as exploiting implicit negative evidence and includes a wide class of likelihoodbased objective functions. This criterion is a generalization ..."
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Cited by 25 (7 self)
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We describe a novel training criterion for probabilistic grammar induction models, contrastive estimation [Smith and Eisner, 2005], which can be interpreted as exploiting implicit negative evidence and includes a wide class of likelihoodbased objective functions. This criterion is a generalization of the function maximized by the ExpectationMaximization algorithm [Dempster et al., 1977]. CE is a natural fit for loglinear models, which can include arbitrary features but for which EM is computationally difficult. We show that, using the same features, loglinear dependency grammar models trained using CE can drastically outperform EMtrained generative models on the task of matching human linguistic annotations (the MATCHLINGUIST task). The selection of an implicit negative evidence class—a “neighborhood”—appropriate to a given task has strong implications, but a good neighborhood one can target the objective of grammar induction to a specific application. 1
Computationally Efficient MEstimation of LogLinear Structure Models
, 2007
"... We describe a new loss function, due to Jeon and Lin (2006), for estimating structured loglinear models on arbitrary features. The loss function can be seen as a (generative) alternative to maximum likelihood estimation with an interesting informationtheoretic interpretation, and it is statistical ..."
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Cited by 6 (2 self)
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We describe a new loss function, due to Jeon and Lin (2006), for estimating structured loglinear models on arbitrary features. The loss function can be seen as a (generative) alternative to maximum likelihood estimation with an interesting informationtheoretic interpretation, and it is statistically consistent. It is substantially faster than maximum (conditional) likelihood estimation of conditional random fields (Lafferty et al., 2001; an order of magnitude or more). We compare its performance and training time to an HMM, a CRF, an MEMM, and pseudolikelihood on a shallow parsing task. These experiments help tease apart the contributions of rich features and discriminative training, which are shown to be more than additive.
Discriminative Online Algorithms for Sequence Labeling A Comparative Study
"... We describe a natural alternative for training sequence labeling models, based on MIRA (Margin Infused Relaxed Algorithm). In addition, we describe a novel method for performing Viterbilike decoding. We test MIRA and contrast it with other training algorithms and contrast our decoding algorithm ..."
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Cited by 1 (0 self)
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We describe a natural alternative for training sequence labeling models, based on MIRA (Margin Infused Relaxed Algorithm). In addition, we describe a novel method for performing Viterbilike decoding. We test MIRA and contrast it with other training algorithms and contrast our decoding algorithm with the vanilla Viterbi algorithm. 1.