Sparsified State-Space Models are Efficient Highway Networks

Fuente: arXiv
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Autori principali: Song, Woomin, Tack, Jihoon, Mo, Sangwoo, Oh, Seunghyuk, Shin, Jinwoo
Natura: Preprint
Pubblicazione: 2025
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author Song, Woomin
Tack, Jihoon
Mo, Sangwoo
Oh, Seunghyuk
Shin, Jinwoo
author_facet Song, Woomin
Tack, Jihoon
Mo, Sangwoo
Oh, Seunghyuk
Shin, Jinwoo
contents State-space models (SSMs) offer a promising architecture for sequence modeling, providing an alternative to Transformers by replacing expensive self-attention with linear recurrences. In this paper, we propose a simple yet effective trick to enhance SSMs within given computational budgets by sparsifying them. Our intuition is that tokens in SSMs are highly redundant due to gradual recurrent updates, and dense recurrence operations block the delivery of past information. In particular, we observe that upper layers of SSMs tend to be more redundant as they encode global information, while lower layers encode local information. Motivated by this, we introduce Simba, a hierarchical sparsification method for SSMs based on token pruning. Simba sparsifies upper layers more than lower layers, encouraging the upper layers to behave like highways. To achieve this, we propose a novel token pruning criterion for SSMs, measuring the global impact of tokens on the final output by accumulating local recurrences. We demonstrate that Simba outperforms the baseline model, Mamba, with the same FLOPS in various natural language tasks. Moreover, we illustrate the effect of highways, showing that Simba not only enhances efficiency but also improves the information flow across long sequences. Code is available at https://github.com/woominsong/Simba.
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id arxiv_https___arxiv_org_abs_2505_20698
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Sparsified State-Space Models are Efficient Highway Networks
Song, Woomin
Tack, Jihoon
Mo, Sangwoo
Oh, Seunghyuk
Shin, Jinwoo
Machine Learning
State-space models (SSMs) offer a promising architecture for sequence modeling, providing an alternative to Transformers by replacing expensive self-attention with linear recurrences. In this paper, we propose a simple yet effective trick to enhance SSMs within given computational budgets by sparsifying them. Our intuition is that tokens in SSMs are highly redundant due to gradual recurrent updates, and dense recurrence operations block the delivery of past information. In particular, we observe that upper layers of SSMs tend to be more redundant as they encode global information, while lower layers encode local information. Motivated by this, we introduce Simba, a hierarchical sparsification method for SSMs based on token pruning. Simba sparsifies upper layers more than lower layers, encouraging the upper layers to behave like highways. To achieve this, we propose a novel token pruning criterion for SSMs, measuring the global impact of tokens on the final output by accumulating local recurrences. We demonstrate that Simba outperforms the baseline model, Mamba, with the same FLOPS in various natural language tasks. Moreover, we illustrate the effect of highways, showing that Simba not only enhances efficiency but also improves the information flow across long sequences. Code is available at https://github.com/woominsong/Simba.
title Sparsified State-Space Models are Efficient Highway Networks
topic Machine Learning
url https://arxiv.org/abs/2505.20698