Morfessor EM+Prune: Improved subword segmentation with expectation maximization and pruning

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openAccess

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Journal ISSN

Volume Title

A4 Artikkeli konferenssijulkaisussa

Date

2020

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Mcode

Degree programme

Language

en

Pages

10
3944-3953

Series

Proceedings of The 12th Language Resources and Evaluation Conference

Abstract

Data-driven segmentation of words into subword units has been used in various natural language processing applications such as automatic speech recognition and statistical machine translation for almost 20 years. Recently it has became more widely adopted, as models based on deep neural networks often benefit from subword units even for morphologically simpler languages. In this paper, we discuss and compare training algorithms for a unigram subword model, based on the Expectation Maximization algorithm and lexicon pruning. Using English, Finnish, North Sami, and Turkish data sets, we show that this approach is able to find better solutions to the optimization problem defined by the Morfessor Baseline model than its original recursive training algorithm. The improved optimization also leads to higher morphological segmentation accuracy when compared to a linguistic gold standard. We publish implementations of the new algorithms in the widely-used Morfessor software package.

Description

| openaire: EC/H2020/780069/EU//MeMAD

Keywords

Language Modelling, Less-Resourced/Endangered Languages, Morphology, Statistical and Machine Learning Methods, Tools, Unsupervised learning

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Citation

Grönroos, S A, Virpioja, S & Kurimo, M 2020, Morfessor EM+Prune: Improved subword segmentation with expectation maximization and pruning . in N Calzolari, F Bechet, P Blache, K Choukri, C Cieri, T Declerck, S Goggi, H Isahara, B Maegaard, J Mariani, H Mazo, A Moreno, J Odijk & S Piperidis (eds), Proceedings of The 12th Language Resources and Evaluation Conference . European language resources distribution agency, pp. 3944-3953, International Conference on Language Resources and Evaluation, Marseille, France, 11/05/2020 . < https://www.aclweb.org/anthology/2020.lrec-1.486/ >