Complementary Strategies for Low Resourced Morphological Modeling

Alexander Erdmann, Nizar Habash


Abstract
Morphologically rich languages are challenging for natural language processing tasks due to data sparsity. This can be addressed either by introducing out-of-context morphological knowledge, or by developing machine learning architectures that specifically target data sparsity and/or morphological information. We find these approaches to complement each other in a morphological paradigm modeling task in Modern Standard Arabic, which, in addition to being morphologically complex, features ubiquitous ambiguity, exacerbating sparsity with noise. Given a small number of out-of-context rules describing closed class morphology, we combine them with word embeddings leveraging subword strings and noise reduction techniques. The combination outperforms both approaches individually by about 20% absolute. While morphological resources already exist for Modern Standard Arabic, our results inform how comparable resources might be constructed for non-standard dialects or any morphologically rich, low resourced language, given scarcity of time and funding.
Anthology ID:
W18-5806
Volume:
Proceedings of the Fifteenth Workshop on Computational Research in Phonetics, Phonology, and Morphology
Month:
October
Year:
2018
Address:
Brussels, Belgium
Venues:
EMNLP | WS
SIG:
SIGMORPHON
Publisher:
Association for Computational Linguistics
Note:
Pages:
54–65
Language:
URL:
https://www.aclweb.org/anthology/W18-5806
DOI:
10.18653/v1/W18-5806
Bib Export formats:
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PDF:
http://aclanthology.lst.uni-saarland.de/W18-5806.pdf