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Bibliographic Details
Main Authors: Strobl, Lena, Angluin, Dana, Chiang, David, Rawski, Jonathan, Sabharwal, Ashish
Format: Preprint
Published: 2024
Subjects:
Online Access:https://arxiv.org/abs/2404.02040
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Table of Contents:
  • We study the sequence-to-sequence mapping capacity of transformers by relating them to finite transducers, and find that they can express surprisingly large classes of transductions. We do so using variants of RASP, a programming language designed to help people "think like transformers," as an intermediate representation. We extend the existing Boolean variant B-RASP to sequence-to-sequence functions and show that it computes exactly the first-order rational functions (such as string rotation). Then, we introduce two new extensions. B-RASP[pos] enables calculations on positions (such as copying the first half of a string) and contains all first-order regular functions. S-RASP adds prefix sum, which enables additional arithmetic operations (such as squaring a string) and contains all first-order polyregular functions. Finally, we show that masked average-hard attention transformers can simulate S-RASP.