Distillation without aligned feature spaces, using a shared bank of random frozen prototypes
AspireAI community · arXiv
A widely held assumption in knowledge distillation is that teacher and student representations must live in compatible or explicitly aligned feature spaces. RPKD discards it: both networks are compared against a shared bank of randomly initialised, frozen prototype vectors, so alignment happens in an external reference space rather than in the teacher's native coordinates. The teacher side is projected by fixed random maps with no trainable parameters, and only the student adapts. Two branches handle the transfer - a logit branch aligning global prototype similarity distributions and a feature branch matching spatially-resolved prototype activation maps - operating in the same fixed prototype space, which can be read as a random feature embedding that approximately preserves inter-sample similarity structure. That keeps the prototype bank and objective unchanged across teacher-student pairs while only the input projections differ per architecture. Reported gains reach +7.98% over OFA on CIFAR-100, +12.44% on ImageNet-100 and +1.28% on ImageNet-1K. NeurIPS 2026.
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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.