Diffusion language models can retrieve mid-denoising, and it makes them 4x faster
AspireAI community · arXiv (ICML 2026)
SARDI shows that the noisy draft a diffusion language model carries mid-denoising already surfaces the entities an answer will need, so retrieval can run while the model is still writing rather than after. Grounding the generation in retrieved evidence also flattens the token-to-token dependencies that make parallel decoding brittle, which is why the paper reports up to 4x higher throughput than autoregressive retrieval baselines across five multi-hop QA benchmarks. The method needs no training and works with any retriever, but it only applies to discrete diffusion language models, which remain a narrow slice of what people actually run in production.
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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.