Minimalist Softmax Attention Provably Learns Constrained Boolean Functions

Fuente: arXiv
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Autori principali: Hu, Jerry Yao-Chieh, Zhang, Xiwen, Su, Maojiang, Song, Zhao, Liu, Han
Natura: Preprint
Pubblicazione: 2025
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author Hu, Jerry Yao-Chieh
Zhang, Xiwen
Su, Maojiang
Song, Zhao
Liu, Han
author_facet Hu, Jerry Yao-Chieh
Zhang, Xiwen
Su, Maojiang
Song, Zhao
Liu, Han
contents We study the computational limits of learning $k$-bit Boolean functions (specifically, $\mathrm{AND}$, $\mathrm{OR}$, and their noisy variants), using a minimalist single-head softmax-attention mechanism, where $k=Θ(d)$ relevant bits are selected from $d$ inputs. We show that these simple $\mathrm{AND}$ and $\mathrm{OR}$ functions are unsolvable with a single-head softmax-attention mechanism alone. However, with teacher forcing, the same minimalist attention is capable of solving them. These findings offer two key insights: Architecturally, solving these Boolean tasks requires only minimalist attention, without deep Transformer blocks or FFNs. Methodologically, one gradient descent update with supervision suffices and replaces the multi-step Chain-of-Thought (CoT) reasoning scheme of [Kim and Suzuki, ICLR 2025] for solving Boolean problems. Together, the bounds expose a fundamental gap between what this minimal architecture achieves under ideal supervision and what is provably impossible under standard training.
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id arxiv_https___arxiv_org_abs_2505_19531
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Minimalist Softmax Attention Provably Learns Constrained Boolean Functions
Hu, Jerry Yao-Chieh
Zhang, Xiwen
Su, Maojiang
Song, Zhao
Liu, Han
Machine Learning
Artificial Intelligence
We study the computational limits of learning $k$-bit Boolean functions (specifically, $\mathrm{AND}$, $\mathrm{OR}$, and their noisy variants), using a minimalist single-head softmax-attention mechanism, where $k=Θ(d)$ relevant bits are selected from $d$ inputs. We show that these simple $\mathrm{AND}$ and $\mathrm{OR}$ functions are unsolvable with a single-head softmax-attention mechanism alone. However, with teacher forcing, the same minimalist attention is capable of solving them. These findings offer two key insights: Architecturally, solving these Boolean tasks requires only minimalist attention, without deep Transformer blocks or FFNs. Methodologically, one gradient descent update with supervision suffices and replaces the multi-step Chain-of-Thought (CoT) reasoning scheme of [Kim and Suzuki, ICLR 2025] for solving Boolean problems. Together, the bounds expose a fundamental gap between what this minimal architecture achieves under ideal supervision and what is provably impossible under standard training.
title Minimalist Softmax Attention Provably Learns Constrained Boolean Functions
topic Machine Learning
Artificial Intelligence
url https://arxiv.org/abs/2505.19531