Extracting Event Temporal Relations via Hyperbolic Geometry

Xingwei Tan, Gabriele Pergola, Yulan He


Abstract
Detecting events and their evolution through time is a crucial task in natural language understanding. Recent neural approaches to event temporal relation extraction typically map events to embeddings in the Euclidean space and train a classifier to detect temporal relations between event pairs. However, embeddings in the Euclidean space cannot capture richer asymmetric relations such as event temporal relations. We thus propose to embed events into hyperbolic spaces, which are intrinsically oriented at modeling hierarchical structures. We introduce two approaches to encode events and their temporal relations in hyperbolic spaces. One approach leverages hyperbolic embeddings to directly infer event relations through simple geometrical operations. In the second one, we devise an end-to-end architecture composed of hyperbolic neural units tailored for the temporal relation extraction task. Thorough experimental assessments on widely used datasets have shown the benefits of revisiting the tasks on a different geometrical space, resulting in state-of-the-art performance on several standard metrics. Finally, the ablation study and several qualitative analyses highlighted the rich event semantics implicitly encoded into hyperbolic spaces.
Anthology ID:
2021.emnlp-main.636
Volume:
Proceedings of the 2021 Conference on Empirical Methods in Natural Language Processing
Month:
November
Year:
2021
Address:
Online and Punta Cana, Dominican Republic
Venue:
EMNLP
SIG:
Publisher:
Association for Computational Linguistics
Note:
Pages:
8065–8077
Language:
URL:
https://aclanthology.org/2021.emnlp-main.636
DOI:
10.18653/v1/2021.emnlp-main.636
Bibkey:
Cite (ACL):
Xingwei Tan, Gabriele Pergola, and Yulan He. 2021. Extracting Event Temporal Relations via Hyperbolic Geometry. In Proceedings of the 2021 Conference on Empirical Methods in Natural Language Processing, pages 8065–8077, Online and Punta Cana, Dominican Republic. Association for Computational Linguistics.
Cite (Informal):
Extracting Event Temporal Relations via Hyperbolic Geometry (Tan et al., EMNLP 2021)
Copy Citation:
PDF:
https://aclanthology.org/2021.emnlp-main.636.pdf
Video:
 https://aclanthology.org/2021.emnlp-main.636.mp4
Code
 xingwei-warwick/hyper-event-temprel
Data
TCR