*Speculative decoding gets less efficient exactly when it gets more useful.*
Tree-based speculative decoding verifies many candidate branches in parallel, and in serving traffic where similar requests repeat, retrieved draft trees fill up with low-quality branches that waste target-model compute. ValuSpec is a plug-and-play filter: it estimates a threshold from the target model's own greedy trajectories on a calibration split, with no parameter training, and drops branches the target is unlikely to accept - while the greedy verification rule keeps accepted tokens identical to standard autoregressive decoding.
On HumanEval, GSM8K, Dolly and SpecBench it reached up to 2.38x end-to-end speedup in retrieval-based tree settings, and up to 2.78x when dropped into EAGLE-3's dynamic tree framework without changing how that framework builds its trees.
Caveat: these are 'up to' numbers reported by the authors on their own evaluation setup, and ValuSpec is a research prototype rather than a released serving component.
https://arxiv.org/abs/2610.31338
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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.