On the Existence of Universal Simulators of Attention

Fuente: arXiv
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Main Authors: Dutta, Debanjan, Chakrabarty, Anish, Ansari, Faizanuddin, Das, Swagatam
Format: Preprint
Published: 2025
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author Dutta, Debanjan
Chakrabarty, Anish
Ansari, Faizanuddin
Das, Swagatam
author_facet Dutta, Debanjan
Chakrabarty, Anish
Ansari, Faizanuddin
Das, Swagatam
contents Previous work on the learnability of transformers \textemdash\ focused primarily on examining their ability to approximate specific algorithmic patterns through training \textemdash\ has largely been data-driven, offering only probabilistic guarantees rather than deterministic solutions. Expressivity, on the contrary, has been devised to address the problems \emph{computable} by such architecture theoretically. These results proved the Turing-completeness of transformers, investigated bounds focused on circuit complexity, and formal logic. Being at the crossroad between learnability and expressivity, the question remains: \emph{can a transformer, as a computational model, simulate an arbitrary attention mechanism, or in particular, the underlying operations?} In this study, we investigate the transformer encoder's ability to simulate a vanilla attention mechanism. By constructing a universal simulator $\mathcal{U}$ composed of transformer encoders, we present algorithmic solutions to replicate attention outputs and the underlying elementary matrix and activation operations via RASP, a formal framework for transformer computation. We show the existence of an algorithmically achievable, data-agnostic solution, previously known to be approximated only by learning.
format Preprint
id arxiv_https___arxiv_org_abs_2506_18739
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle On the Existence of Universal Simulators of Attention
Dutta, Debanjan
Chakrabarty, Anish
Ansari, Faizanuddin
Das, Swagatam
Machine Learning
Artificial Intelligence
Previous work on the learnability of transformers \textemdash\ focused primarily on examining their ability to approximate specific algorithmic patterns through training \textemdash\ has largely been data-driven, offering only probabilistic guarantees rather than deterministic solutions. Expressivity, on the contrary, has been devised to address the problems \emph{computable} by such architecture theoretically. These results proved the Turing-completeness of transformers, investigated bounds focused on circuit complexity, and formal logic. Being at the crossroad between learnability and expressivity, the question remains: \emph{can a transformer, as a computational model, simulate an arbitrary attention mechanism, or in particular, the underlying operations?} In this study, we investigate the transformer encoder's ability to simulate a vanilla attention mechanism. By constructing a universal simulator $\mathcal{U}$ composed of transformer encoders, we present algorithmic solutions to replicate attention outputs and the underlying elementary matrix and activation operations via RASP, a formal framework for transformer computation. We show the existence of an algorithmically achievable, data-agnostic solution, previously known to be approximated only by learning.
title On the Existence of Universal Simulators of Attention
topic Machine Learning
Artificial Intelligence
url https://arxiv.org/abs/2506.18739