ETAPS pruned a 7B model to 90 percent sparsity on one H200, with perplexity up to 42 percent below prior work
AspireAI community · arXiv (cs.AI)
Weight pruning cuts storage and inference cost, but quality collapses at high sparsity. One-shot pruning degrades sharply; methods that optimise the mask directly under the end-to-end objective reach high quality but need model-sized optimiser state. ETAPS prunes gradually and adapts sparsely: it tightens a global sparsity constraint in progressive stages while training a sparse delta with a small fixed budget, so each pruning step stays small enough for sparse adaptation to compensate and the adapted model can supply end-to-end gradients that guide the next pruning decision. Across six models from 125M to 13B parameters, ETAPS achieves lower perplexity than ELSA at every evaluated sparsity from 50 to 90 percent, with perplexity reductions of up to 42 percent. It is also cheaper: at 90 percent sparsity ETAPS prunes LLaMA2-7B on a single H200 where ELSA uses four, with 5.0x smaller persistent state and 49 percent fewer GPU-hours.
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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.