Towards a mathematical theory of superposition

arXiv:2608.27540 2026 Architecture 1 ideas extracted · analyzed Sep 1, 2026

What the math gives to ML

The paper supplies a concrete superposition mechanism: represent a high-dimensional sparse feature vector through an overcomplete dictionary and decode it with a single ReLU applied to the dictionary Gram operator. The transferable asset is the connection between recoverability and dictionary geometry, especially normalization, near-tightness, and low mutual coherence, rather than sparse coding as a generic objective. A practical neural-network adaptation is a coherence-aware overcomplete bottleneck for MLP or embedding activations, with analytically chosen ReLU biases that suppress cross-feature interference and an explicit coherence regularizer. This is experimentally testable against a standard sparse autoencoder by measuring support precision, reconstruction error, and downstream task accuracy at the same bottleneck width.

Ideas from this paper

Unverified 2026

Coherence-aware superposition bottleneck

Insert an overcomplete sparse feature bottleneck into an MLP or embedding stream: encode an activation h with z = ReLU(W^T h + b), then reconstruct or continue computation from Wz. Normalize dictionary columns and train them to remain nearly tight and low-coherence, while choosing a negative bias from an estimate of worst-case cross-feature interference. The hypothesis is that this gives cleaner, more stable feature supports than an ordinary L1 sparse autoencoder at the same latent width.

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Paper: Towards a mathematical theory of superposition arXiv:2608.27540