Towards Understanding Linear Word Analogies

Kawin Ethayarajh, David Duvenaud, Graeme Hirst


Abstract
A surprising property of word vectors is that word analogies can often be solved with vector arithmetic. However, it is unclear why arithmetic operators correspond to non-linear embedding models such as skip-gram with negative sampling (SGNS). We provide a formal explanation of this phenomenon without making the strong assumptions that past theories have made about the vector space and word distribution. Our theory has several implications. Past work has conjectured that linear substructures exist in vector spaces because relations can be represented as ratios; we prove that this holds for SGNS. We provide novel justification for the addition of SGNS word vectors by showing that it automatically down-weights the more frequent word, as weighting schemes do ad hoc. Lastly, we offer an information theoretic interpretation of Euclidean distance in vector spaces, justifying its use in capturing word dissimilarity.
Anthology ID:
P19-1315
Volume:
Proceedings of the 57th Annual Meeting of the Association for Computational Linguistics
Month:
July
Year:
2019
Address:
Florence, Italy
Editors:
Anna Korhonen, David Traum, Lluís Màrquez
Venue:
ACL
SIG:
Publisher:
Association for Computational Linguistics
Note:
Pages:
3253–3262
Language:
URL:
https://aclanthology.org/P19-1315
DOI:
10.18653/v1/P19-1315
Bibkey:
Cite (ACL):
Kawin Ethayarajh, David Duvenaud, and Graeme Hirst. 2019. Towards Understanding Linear Word Analogies. In Proceedings of the 57th Annual Meeting of the Association for Computational Linguistics, pages 3253–3262, Florence, Italy. Association for Computational Linguistics.
Cite (Informal):
Towards Understanding Linear Word Analogies (Ethayarajh et al., ACL 2019)
Copy Citation:
PDF:
https://aclanthology.org/P19-1315.pdf