arXiv Machine Learning

Transmission Factors for Lossy Compression of PDE Training Data: Measuring What Reaches a Trained Operator

The paper discusses how operator‑learning benchmarks are stored as full‑precision arrays that have grown to terabyte scale, and curators must decide how coarsely to compress them. It argues that the usual tolerance on reconstruction error of the stored field is measured in the wrong place, because what matters is the accuracy of a model trained on the compressed copy, not the raw field error. The authors propose a new metric: push a compressed field through a model trained at full precision and compare its output to the output on the clean field, which captures the portion of codec error that actually reaches the model’s output. This metric spans more than two orders of magnitude across six PDE families and correctly orders downstream cost where field error does not, reversing many cross‑dataset comparisons.

arXiv Machine Learning
Oct 28

Speculative Decoding for Mixture-of-Experts Models: Expert Bytes, Kernel Bandwidth and the Best Draft Length

The paper investigates speculative decoding for mixture‑of‑experts (MoE) language models, focusing on how deduplication of expert reads can reduce byte traffic and improve decoding speed. By modeling step time as a function of bytes requested and kernel bandwidth, the authors derive conditions under which speculation outperforms plain decoding and identify the optimal draft length as a staircase function of acceptance rate. Experiments on llama.cpp Metal, MLX‑LM, and llama.cpp CUDA show that deduplication is only faster for very short draft lengths (5–8 tokens) or not at all, and the predicted crossover points closely match measured savings across multiple configurations.

By Yuzheng Lan
arXiv Machine Learning
Oct 2

Backward-State Policy Is Part of the Learning Algorithm

The paper argues that the policy governing how tensors are rounded and reused during the backward pass—termed the backward‑state policy—is an integral part of the learning algorithm, not merely a memory or precision detail. Experiments with 390 M‑parameter models show that whether the backward pass reuses a forward’s rounded output or generates a new rounding can decisively affect training success, even when copy accuracy is high. The authors propose a method to determine, for each operator, which value should be read or substituted to preserve the correct gradient, and validate these predictions on PyTorch and Transformer Engine.

By Shuxiao Xie, Shuyang Xie, Dezhi Ran, Wei Yang, Tao Xie
arXiv AI
Jul 16

ShortOPD: Recovering Pruned LLMs with Short-to-Long On-Policy Distillation

arXiv:2607. 13124v1 Announce Type: cross Abstract: Structured pruning is a hardware-friendly way to compress LLMs, but it is mostly validated on multiple-choice recognition tasks, while the same compressed checkpoints can collapse on the free-form generation that deployment actually requires.

By Qingyu Zhang, Qianhao Yuan, Hongyu Lin, Yaojie Lu, Xianpei Han, Le Sun, Xiang Li, Ming Xu, Jiarui Li, Xiuyin Zhao
arXiv Machine Learning
Oct 22

When Thoughts Become Memory: Unifying In-Context Learning and Fine-Tuning

The paper presents a certified rule that determines whether unseen data should be incorporated into a pretrained model’s context or its weights, based on an exact law for their information value. This law quantifies the code length saved on held‑out queries as the expected bits stored about the query, adjusted by a prior repair and decoding loss, and applies to any model, architecture, dataset, or task. The authors demonstrate that the rule’s ceilings correctly certify choices across diverse models—including transformers, TabPFN, occupancy networks, and stereo networks—and that an anytime‑valid test can reliably select the better approach (e.g., TabPFN over XGBoost or GPT‑2’s cache over fine‑tuning) with controlled error rates.

By Leon Chlon, Julie Huang