To Lemmatize or Not to Lemmatize: How Word Normalisation Affects ELMo Performance in Word Sense Disambiguation

Andrey Kutuzov, Elizaveta Kuzmenko


Abstract
In this paper, we critically evaluate the widespread assumption that deep learning NLP models do not require lemmatized input. To test this, we trained versions of contextualised word embedding ELMo models on raw tokenized corpora and on the corpora with word tokens replaced by their lemmas. Then, these models were evaluated on the word sense disambiguation task. This was done for the English and Russian languages. The experiments showed that while lemmatization is indeed not necessary for English, the situation is different for Russian. It seems that for rich-morphology languages, using lemmatized training and testing data yields small but consistent improvements: at least for word sense disambiguation. This means that the decisions about text pre-processing before training ELMo should consider the linguistic nature of the language in question.
Anthology ID:
W19-6203
Volume:
Proceedings of the First NLPL Workshop on Deep Learning for Natural Language Processing
Month:
September
Year:
2019
Address:
Turku, Finland
Editors:
Joakim Nivre, Leon Derczynski, Filip Ginter, Bjørn Lindi, Stephan Oepen, Anders Søgaard, Jörg Tidemann
Venue:
NoDaLiDa
SIG:
Publisher:
Linköping University Electronic Press
Note:
Pages:
22–28
Language:
URL:
https://aclanthology.org/W19-6203
DOI:
Bibkey:
Cite (ACL):
Andrey Kutuzov and Elizaveta Kuzmenko. 2019. To Lemmatize or Not to Lemmatize: How Word Normalisation Affects ELMo Performance in Word Sense Disambiguation. In Proceedings of the First NLPL Workshop on Deep Learning for Natural Language Processing, pages 22–28, Turku, Finland. Linköping University Electronic Press.
Cite (Informal):
To Lemmatize or Not to Lemmatize: How Word Normalisation Affects ELMo Performance in Word Sense Disambiguation (Kutuzov & Kuzmenko, NoDaLiDa 2019)
Copy Citation:
PDF:
https://preview.aclanthology.org/emnlp22-frontmatter/W19-6203.pdf
Data
RUSSE