A linear time approximation of Wasserstein distance with word embedding selection

Sho Otao, Makoto Yamada


Abstract
Wasserstein distance, which can be computed by solving the optimal transport problem, is a powerful method for measuring the dissimilarity between documents. In the NLP community, it is referred to as word mover’s distance (WMD). One of the key challenges of Wasserstein distance is its computational cost since it needs cubic time. Although the Sinkhorn algorithm is a powerful tool to speed up to compute the Wasserstein distance, it still requires square time. Recently, a linear time approximation of the Wasserstein distance including the sliced Wasserstein and the tree-Wasserstein distance (TWD) has been proposed. However, a linear time approximation method suffers when the dimensionality of word vectors is high. In this study, we propose a method to combine feature selection and tree approximation of Wasserstein distance to handle high-dimensional problems. More specifically, we use multiple word embeddings and automatically select useful word embeddings in a tree approximation of Wasserstein distance. To this end, we approximate Wasserstein distance for each word vector by tree approximation technique, and select the discriminative (i.e., large Wasserstein distance) word embeddings by solving an entropic regularized maximization problem. Through our experiments on document classification, our proposed method achieved high performance.
Anthology ID:
2023.emnlp-main.935
Volume:
Proceedings of the 2023 Conference on Empirical Methods in Natural Language Processing
Month:
December
Year:
2023
Address:
Singapore
Editors:
Houda Bouamor, Juan Pino, Kalika Bali
Venue:
EMNLP
SIG:
Publisher:
Association for Computational Linguistics
Note:
Pages:
15121–15134
Language:
URL:
https://aclanthology.org/2023.emnlp-main.935
DOI:
10.18653/v1/2023.emnlp-main.935
Bibkey:
Cite (ACL):
Sho Otao and Makoto Yamada. 2023. A linear time approximation of Wasserstein distance with word embedding selection. In Proceedings of the 2023 Conference on Empirical Methods in Natural Language Processing, pages 15121–15134, Singapore. Association for Computational Linguistics.
Cite (Informal):
A linear time approximation of Wasserstein distance with word embedding selection (Otao & Yamada, EMNLP 2023)
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