arXiv Computation and Language

The Cost of Compression: A Rate-Distortion Limit on Factual Hallucination

The paper presents a rate‑distortion framework for understanding factual hallucination in closed‑book question answering. It shows that even when a fact is observed, limited memory forces it to be stored approximately, leading to errors that can be bounded by a combination of compression distortion and missing coverage. The authors derive a theoretical lower bound on error and validate it with simulations and probes on modern language models.

arXiv Machine Learning
Jul 15

Extractable Memorization From First Principles

arXiv:2607. 12649v1 Announce Type: new Abstract: Recent work on extractable memorization in LLMs suffers from two contrasting validity problems.

By A. Feder Cooper, Marika Swanberg, Jamie Hayes, Lea Duesterwald, Christopher De Sa, Daniel E. Ho, Mark A. Lemley, Percy Liang
arXiv Machine Learning
Oct 5

Capability Scaling-Down Laws for LLM Compression

The paper presents a systematic study of how different compression techniques—pruning, quantization, and distillation—affect the capabilities of large language models (LLMs) in tasks such as mathematics, code generation, and question answering. It introduces a framework that measures capability loss and relates it to factors like model size, training stage, and compression settings, yielding simple predictive relations that generalize across unseen configurations. The authors demonstrate that sharing density responses across pruning levels can dramatically reduce the number of measurements needed, and that their predictive models closely match regression results while offering efficient decision guidance for compression method selection.

By Xueqi Cheng, Liang Wu, Kelly Wan, Liangjie Hong, Yushun Dong
arXiv Computation and Language
3d ago

From Lookups to Lessons: Turning Retrieved Knowledge into Parametric Memory

The paper introduces ResMem, a method that transforms retrieved knowledge into a parametric memory for large language models. By using the LLM as an offline teacher that reads retrieved text, ResMem learns an additive logit residual, avoiding large token storage and improving question‑answering performance. Experiments on Wikipedia and five QA datasets show significant storage savings and higher token F1 scores compared to k‑NN baselines.

By Changjiang Han, Bowei He, Ye Yuan, Weixu Zhang, Haolun Wu, Xue Liu, Jikun Kang
arXiv Machine Learning
5d ago

When Less is More: The LLM Scaling Paradox in Context Compression

The paper reports a Size‑Fidelity Paradox in large‑language‑model (LLM) context compression: larger compressors can produce lower reconstruction error yet yield less faithful reconstructed contexts. Two key mechanisms drive this effect: knowledge overwriting, where larger models replace source facts with their own beliefs, and semantic drift, where they paraphrase or restructure content. Across 27 compressor setups, mid‑sized models often recover contexts more faithfully, and analysis of embedding geometry shows that larger models organize memory into broader semantic subspaces, leading to ambiguous representations that weaken recovery.

By Ruishan Guo, Yibing Liu, Guoxin Ma, Yan Wang, Yueyang Zhang, Long Xia, Kecheng Chen, Zhiyuan Sun, Daiting Shi
arXiv Computation and Language
Oct 19

On the Tip of the Tongue: First-Token Cueing as a Behavioral Probe of Recall Failures in LLMs

The paper investigates why large language models often answer factual questions incorrectly in closed‑book settings. It shows that many errors are due to first‑token recall failures: the model commits to an incorrect first token but can complete the correct answer once the right token is provided. Using a First‑Token Cueing probe, the authors demonstrate that correcting just the first token recovers a significant portion of errors across 16 open models and improves accuracy on multilingual benchmarks.

By Jaewon Sok, Jewon Yeom, Seonghyeon Park, Jeongjae Park, Hwiyeong Lee, Taesup Kim