Learning to Lemmatize in the Word Representation Space

Jarkko Lagus, Arto Klami


Abstract
Lemmatization is often used with morphologically rich languages to address issues caused by morphological complexity, performed by grammar-based lemmatizers. We propose an alternative for this, in form of a tool that performs lemmatization in the space of word embeddings. Word embeddings as distributed representations natively encode some information about the relationship between base and inflected forms, and we show that it is possible to learn a transformation that approximately maps the embeddings of inflected forms to the embeddings of the corresponding lemmas. This facilitates an alternative processing pipeline that replaces traditional lemmatization with the lemmatizing transformation in downstream processing for any application. We demonstrate the method in the Finnish language, outperforming traditional lemmatizers in example task of document similarity comparison, but the approach is language independent and can be trained for new languages with mild requirements.
Anthology ID:
2021.nodalida-main.25
Volume:
Proceedings of the 23rd Nordic Conference on Computational Linguistics (NoDaLiDa)
Month:
May 31--2 June
Year:
2021
Address:
Reykjavik, Iceland (Online)
Editors:
Simon Dobnik, Lilja Øvrelid
Venue:
NoDaLiDa
SIG:
Publisher:
Linköping University Electronic Press, Sweden
Note:
Pages:
249–258
Language:
URL:
https://aclanthology.org/2021.nodalida-main.25
DOI:
Bibkey:
Cite (ACL):
Jarkko Lagus and Arto Klami. 2021. Learning to Lemmatize in the Word Representation Space. In Proceedings of the 23rd Nordic Conference on Computational Linguistics (NoDaLiDa), pages 249–258, Reykjavik, Iceland (Online). Linköping University Electronic Press, Sweden.
Cite (Informal):
Learning to Lemmatize in the Word Representation Space (Lagus & Klami, NoDaLiDa 2021)
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PDF:
https://aclanthology.org/2021.nodalida-main.25.pdf