Unsupervised Part-of-Speech Induction

Evaluating Unsupervised Part-of-Speech Tagging for Grammar Induction

This paper explores the relationship between various measures of unsupervised part-of-speech tag induction and the performance of both supervised and unsupervised parsing models trained on induced tags. We find that no standard tagging metrics correlate well with unsupervised parsing performance, and several metrics grounded in information theory have no strong relationship with even supervised...

A Universal Part-of-Speech Tagset

To facilitate future research in unsupervised induction of syntactic structure and to standardize best-practices, we propose a tagset that consists of twelve universal part-ofspeech categories. In addition to the tagset, we develop a mapping from 25 different treebank tagsets to this universal set. As a result, when combined with the original treebank data, this universal tagset and mapping pro...

Unsupervised Morphology Induction for Part-of-speech-tagging

Online EM for Unsupervised Models

The (batch) EM algorithm plays an important role in unsupervised induction, but it sometimes suffers from slow convergence. In this paper, we show that online variants (1) provide significant speedups and (2) can even find better solutions than those found by batch EM. We support these findings on four unsupervised tasks: part-of-speech tagging, document classification, word segmentation, and w...

Addressing Ambiguity in Unsupervised Part-of-Speech Induction with Substitute Vectors

We study substitute vectors to solve the part-of-speech ambiguity problem in an unsupervised setting. Part-of-speech tagging is a crucial preliminary process in many natural language processing applications. Because many words in natural languages have more than one part-of-speech tag, resolving part-of-speech ambiguity is an important task. We claim that partof-speech ambiguity can be solved u...

Part of Speech Induction using Non-negative Matrix Factorization

Unsupervised part-of-speech induction involves the discovery of syntactic categories in a text, given no additional information other than the text itself. One requirement of an induction system is the ability to handle multiple categories for each word, in order to deal with word sense ambiguity. We construct an algorithm for unsupervised part-of-speech induction, treating the problem as one o...