arXiv Machine Learning

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.

arXiv AI
1d ago

Does Context Compression Preserve Refusal Alignment?

The paper examines whether context compression, which encodes inputs into compact representations while preserving semantic content, maintains refusal alignment in instruction-tuned language models. It finds that encoder-based compression consistently weakens refusal behavior across various model families and architectures, even though reconstruction fidelity remains high. Mechanistic analysis attributes this to attenuation of activation along the decoder’s learned refusal direction, and introduces Memory Steering—a lightweight inference-time intervention that restores refusal rates without retraining.

By Anthony Nguyen, Wenjun Lin
arXiv AI
Sep 10

Limits of Reliability and Scaling in Language Models

The paper argues that large language models cannot achieve perfect reliability for any task, even with unlimited scale. It establishes that each generative task has an inherent reliability ceiling set by how much output uncertainty can be resolved from observable context, with a resolvable part that can be improved by more context and a subjective part tied to task ambiguity. The authors derive a scaling law showing that performance is limited by the scarcer resource—either training data or model capacity—and explain how this law explains phenomena such as retrieval augmentation and catastrophic forgetting.

By Subhabrata Majumdar
arXiv AI
Sep 4

Knowledge Acquisition During Pre-training? Large Language Models Learn Better With Auxiliary Views

The paper investigates how large language models acquire knowledge during pre‑training, proposing that auxiliary views—reformulations of knowledge—are causally beneficial. Experiments show that repetition is essential, paraphrasing helps only at smaller batch sizes, and reallocating tokens from repetition to auxiliary views improves learning even for factual recall. The study also finds that the benefit of auxiliary views does not depend on the teacher model’s strength, identifies specific knowledge types that aid learning, and explores mechanistic effects via layer‑wise biases and compression.

By Joseph Lee, Yidi Huang, Dokyoon Kim, Shu Yang, Li Shen
arXiv Computation and Language
Oct 23

Meaning Contracts: Local Semantic Geometry in Large Language Models

The paper investigates how semantic meaning is arranged locally within large language models. By using two controlled probes—one cross‑lingual and one refinement probe—on four decoder‑only LLMs, it finds that after removing dominant variance directions, sentence pairs rank by semantic relatedness, semantic factors cluster around an invariant core with structured variation, refinement tightens neighborhoods, and sentence‑level versus token‑local readouts reveal complementary geometric patterns. These results suggest that LLM semantics form local anisotropic neighborhoods that contract when meaning is refined.

By Andr\'es Daniel Godoy Ortiz