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MERLIN gave linear attention a second-order routing signal and picked up 8 to 13 percent on long-context work while using less memory than the baselines

AspireAI community · arXiv
*Multi-state linear attention splits long context into segments, compresses each into its own memory state, and then aggregates across states using only the mean alignment between a query and each segment's keys - ignoring how that alignment is distributed inside the segment.* MERLIN tracks the first and second moments of each segment's keys, which lets a query recover both the mean and the variance of its alignment with each segment and aggregate the per-state readouts with that content awareness in hand. On multi-state variants of Gated DeltaNet-1.3B and Mamba-2-780M the method consistently beats existing aggregation methods on long-context tasks: long-context QA improves by 8.3 percent and 7.0 percent respectively, and diverse LongBench subtasks by 13.5 percent and 12.0 percent. It also beats baselines that consume four times more memory. The limitation: the gains are measured on two specific multi-state backbones rather than across the broader linear-attention family, and the second-order moment adds state that has to be maintained per segment.
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One distance function matched sparse-autoencoder features across layers and compressed feature circuits into supernodes
Two sparse-autoencoder analyses have resisted scaling: matching semantically similar features across layers, and compressing large feature circuits into interpretable supernodes. This paper argues both are the same underlying problem, estimating semantic distances between SAE features that sit on different activation manifolds. Its representation treats each feature not as a single decoder vector but as an activation-weighted distribution over the hidden states expressing it, projects those distributions into a shared reference space, and compares them with Wasserstein distance. The representation is proved invariant to activation rescaling and stable under perturbation, and recovers true matches under finite-sample margin conditions. Empirically it outperformed decoder-vector and LLM-based baselines and captured subtle functional distinctions between related features, and it compressed large feature circuits into interpretable supernodes automatically. The limitation is that this is interpretability tooling: the paper demonstrates better feature matching and circuit compression, not that downstream interpretability claims become more accurate.
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