Alexander Clark


2021

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Strong Learning of Probabilistic Tree Adjoining Grammars
Alexander Clark
Proceedings of the Society for Computation in Linguistics 2021

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Consistent unsupervised estimators for anchored PCFGs
Alexander Clark | Nathanaël Fijalkow
Proceedings of the Society for Computation in Linguistics 2021

2020

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Consistent Unsupervised Estimators for Anchored PCFGs
Alexander Clark | Nathanaël Fijalkow
Transactions of the Association for Computational Linguistics, Volume 8

Learning probabilistic context-free grammars (PCFGs) from strings is a classic problem in computational linguistics since Horning (1969). Here we present an algorithm based on distributional learning that is a consistent estimator for a large class of PCFGs that satisfy certain natural conditions including being anchored (Stratos et al., 2016). We proceed via a reparameterization of (top--down) PCFGs that we call a bottom–up weighted context-free grammar. We show that if the grammar is anchored and satisfies additional restrictions on its ambiguity, then the parameters can be directly related to distributional properties of the anchoring strings; we show the asymptotic correctness of a naive estimator and present some simulations using synthetic data that show that algorithms based on this approach have good finite sample behavior.

2015

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Canonical Context-Free Grammars and Strong Learning: Two Approaches
Alexander Clark
Proceedings of the 14th Meeting on the Mathematics of Language (MoL 2015)

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Unsupervised Prediction of Acceptability Judgements
Jey Han Lau | Alexander Clark | Shalom Lappin
Proceedings of the 53rd Annual Meeting of the Association for Computational Linguistics and the 7th International Joint Conference on Natural Language Processing (Volume 1: Long Papers)

2014

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Distributional Learning as a Theory of Language Acquisition
Alexander Clark
Proceedings of the 5th Workshop on Cognitive Aspects of Computational Language Learning (CogACLL)

2013

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Statistical Representation of Grammaticality Judgements: the Limits of N-Gram Models
Alexander Clark | Gianluca Giorgolo | Shalom Lappin
Proceedings of the Fourth Annual Workshop on Cognitive Modeling and Computational Linguistics (CMCL)

2010

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Efficient, Correct, Unsupervised Learning for Context-Sensitive Languages
Alexander Clark
Proceedings of the Fourteenth Conference on Computational Natural Language Learning

2009

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Another Look at Indirect Negative Evidence
Alexander Clark | Shalom Lappin
Proceedings of the EACL 2009 Workshop on Cognitive Aspects of Computational Language Acquisition

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A Note on Contextual Binary Feature Grammars
Alexander Clark | Rémi Eyraud | Amaury Habrard
Proceedings of the EACL 2009 Workshop on Computational Linguistic Aspects of Grammatical Inference

2008

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CoNLL 2008: Proceedings of the Twelfth Conference on Computational Natural Language Learning
Alexander Clark | Kristina Toutanova
CoNLL 2008: Proceedings of the Twelfth Conference on Computational Natural Language Learning

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A Comparative Study of Mixture Models for Automatic Topic Segmentation of Multiparty Dialogues
Maria Georgescul | Alexander Clark | Susan Armstrong
Proceedings of the Third International Joint Conference on Natural Language Processing: Volume-II

2006

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An Analysis of Quantitative Aspects in the Evaluation of Thematic Segmentation Algorithms
Maria Georgescul | Alexander Clark | Susan Armstrong
Proceedings of the 7th SIGdial Workshop on Discourse and Dialogue

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Word Distributions for Thematic Segmentation in a Support Vector Machine Approach
Maria Georgescul | Alexander Clark | Susan Armstrong
Proceedings of the Tenth Conference on Computational Natural Language Learning (CoNLL-X)

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Learning Auxiliary Fronting with Grammatical Inference
Alexander Clark | Rémi Eyraud
Proceedings of the Tenth Conference on Computational Natural Language Learning (CoNLL-X)

2005

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Proceedings of the Workshop on Psychocomputational Models of Human Language Acquisition
William Gregory Sakas | Alexander Clark | Royal Holloway | James Cussens | Aris Xanthos
Proceedings of the Workshop on Psychocomputational Models of Human Language Acquisition

2004

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Partially Distribution-Free Learning of Regular Languages from Positive Samples
Alexander Clark | Franck Thollard
COLING 2004: Proceedings of the 20th International Conference on Computational Linguistics

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Grammatical Inference and First Language Acquisition
Alexander Clark
Proceedings of the Workshop on Psycho-Computational Models of Human Language Acquisition

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Multi-level Dialogue Act Tags
Alexander Clark | Andrei Popescu-Belis
Proceedings of the 5th SIGdial Workshop on Discourse and Dialogue at HLT-NAACL 2004

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Building and Using a Corpus of Shallow Dialogue Annotated Meetings
Andrei Popescu-Belis | Maria Georgescul | Alexander Clark | Susan Armstrong
Proceedings of the Fourth International Conference on Language Resources and Evaluation (LREC’04)

2003

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Combining Distributional and Morphological Information for Part of Speech Induction
Alexander Clark
10th Conference of the European Chapter of the Association for Computational Linguistics

2002

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Memory-Based Learning of Morphology with Stochastic Transducers
Alexander Clark
Proceedings of the 40th Annual Meeting of the Association for Computational Linguistics

2001

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Unsupervised induction of stochastic context-free grammars using distributional clustering
Alexander Clark
Proceedings of the ACL 2001 Workshop on Computational Natural Language Learning (ConLL)

2000

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Inducing Syntactic Categories by Context Distribution Clustering
Alexander Clark
Fourth Conference on Computational Natural Language Learning and the Second Learning Language in Logic Workshop