• EM algorithm
• Density estimation, direct maximization of p(x)
• Smith & Eisner 2006 - Contrastive Estimation: Training Log-Linear Models on Unlabeled Data

See also unsupervised constituency parsing and unsupervised dependency parsing.

• Good overview: related work of Nishida 2020 (Gives a good history of unsupervised parsing in the related work)
• Slides from a candidacy exam
• 2020 - An Empirical Comparison of Unsupervised Constituency Parsing Methods

• Klein & Manning 2001 - Corpus-Based Induction of Syntactic Structure: Models of Dependency and Constituency Dependency Model with Valence (DMV). What made Dan Klein famous
• Noah Smith 2006 - Novel Estimation Methods for Unsupervised Discovery of Latent Structure in Natural Language Text What made Noah Smith famous
• Cohen & Smith 2009 - Shared Logistic Normal Distributions for Soft Parameter Tying in Unsupervised Grammar Induction What made Shay Cohen famous
• Drozdov et al 2019 - Unsupervised Latent Tree Induction with Deep Inside-Outside Recursive Autoencoders
• Gupta et al 2020 - Clustering Contextualized Representations of Text for Unsupervised Syntax Induction

• Chaudhary et al 2020 - Automatic Extraction of Rules Governing Morphological Agreement

• Zhang et al 2021 - Video-aided Unsupervised Grammar Induction (Best paper at NAACL 2021)

See also unsupervised morphological analysers.

• Johnson 2007 - Why doesn’t EM find good HMM POS-taggers?
• Ravi & Knight 2009 - Minimized Models for Unsupervised Part-of-Speech Tagging
• Christodoulopoulos et al 2010 - Two Decades of Unsupervised POS induction: How far have we come?
• Gupta et al 2020 - Clustering Contextualized Representations of Text for Unsupervised Syntax Induction

• Poon & Domingos 2009 - Unsupervised Semantic Parsing

See also unsupervised discourse parsing.

• Unsupervised Question Answering
• Unsupervised Machine Translation

• Chambers & Jurafsky 2008 - Unsupervised Learning of Narrative Event Chains

• EM Algorithm
• Unsupervised Constituency Parsing
• Unsupervised Dependency Parsing
• Unsupervised Discourse Parsing