Position Information in Transformers: An Overview

Philipp Dufter, Martin Schmitt, Hinrich Schütze


Abstract
Transformers are arguably the main workhorse in recent natural language processing research. By definition, a Transformer is invariant with respect to reordering of the input. However, language is inherently sequential and word order is essential to the semantics and syntax of an utterance. In this article, we provide an overview and theoretical comparison of existing methods to incorporate position information into Transformer models. The objectives of this survey are to (1) showcase that position information in Transformer is a vibrant and extensive research area; (2) enable the reader to compare existing methods by providing a unified notation and systematization of different approaches along important model dimensions; (3) indicate what characteristics of an application should be taken into account when selecting a position encoding; and (4) provide stimuli for future research.
Anthology ID:
2022.cl-3.7
Volume:
Computational Linguistics, Volume 48, Issue 3 - September 2022
Month:
September
Year:
2022
Address:
Cambridge, MA
Venue:
CL
SIG:
Publisher:
MIT Press
Note:
Pages:
733–763
Language:
URL:
https://aclanthology.org/2022.cl-3.7
DOI:
10.1162/coli_a_00445
Bibkey:
Cite (ACL):
Philipp Dufter, Martin Schmitt, and Hinrich Schütze. 2022. Position Information in Transformers: An Overview. Computational Linguistics, 48(3):733–763.
Cite (Informal):
Position Information in Transformers: An Overview (Dufter et al., CL 2022)
Copy Citation:
PDF:
https://aclanthology.org/2022.cl-3.7.pdf
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