Mimetic Initialization Helps State Space Models Learn to Recall

27 Sept 2024 (modified: 05 Feb 2025)Submitted to ICLR 2025EveryoneRevisionsBibTeXCC BY 4.0
Keywords: Mamba, SSM, sequence models, language models, initialization, linear attention
TL;DR: Mamba learns to recall more easily when we initialize it to be more like linear attention
Abstract: Recent work has shown that state space models such as Mamba are significantly worse than Transformers on recall-based tasks due to the fact that their state size is constant with respect to their input sequence length. But in practice, state space models have fairly large state sizes, and we conjecture that they should be able to perform much better at these tasks than previously reported. We investigate whether their poor copying and recall performance could be due in part to training difficulties rather than fundamental capacity constraints. Based on observations of their "attention'' maps, we propose a structured initialization technique that allows state space layers to more readily mimic attention. Across a variety of architecture settings, our initialization makes it substantially easier for Mamba to learn to copy and do associative recall from scratch.
Primary Area: unsupervised, self-supervised, semi-supervised, and supervised representation learning
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Submission Number: 11529
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