152 research outputs found
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-of-speech 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 produce a dataset consisting of common parts-of-speech for 22
different languages. We highlight the use of this resource via two experiments,
including one that reports competitive accuracies for unsupervised grammar
induction without gold standard part-of-speech tags
Token and Type Constraints for Cross-Lingual Part-of-Speech Tagging
We consider the construction of part-of-speech taggers for resource-poor languages. Recently, manually constructed tag dictionaries from Wiktionary and dictionaries projected via bitext have been used as type constraints to overcome the scarcity of annotated data in this setting. In this paper, we show that additional token constraints can be projected from a resource-rich source language to a resource-poor target language via word-aligned bitext. We present several models to this end; in particular a partially observed conditional random ïŹeld model, where coupled token and type constraints provide a partial signal for training. Averaged across eight previously studied Indo-European languages, our model achieves a 25% relative error reduction over the prior state of the art. We further present successful results on seven additional languages from different families, empirically demonstrating the applicability of coupled token and type constraints across a diverse set of languages
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