Rebalancing Token Importance in Language Models with TF-IDF Weighted Cross-Entropy Loss — Paper

Abstract

Large language models are typically trained under uniform token weighting, which allows frequent and low-information tokens to dominate learning and can increase the tendency to memorize surface-level text spans. To address this, we present an information-weighted cross-entropy loss that rescales token-level contributions using TF-IDF statistics, emphasizing semantically informative tokens while down-weighting ubiquitous ones. Experiments on five decoder-only LLMs ranging from 1.1B to 13B parameters show consistent reductions in memorized substring length while preserving perplexity and downstream task performance. Under LoRA fine-tuning, TF-IDF reduces average substring memorization length by 14% across all five models. Under full-weight fine-tuning on TinyLLaMA 1.1B, the reduction reaches 58%. Our approach is architecture-agnostic and can be incorporated into existing training pipelines with less than 3% computational overhead, offering a lightweight and principled way to mitigate memorization without disrupting standard training dynamics.

Authors 3

Zhijian Li, Stefan Larson, Kevin Leach

Specification

Official page: arxiv.org/abs/2609.11029
Source:arXiv (Atom API + RSS)T1observed 52 min agohigh
Arxiv announce type: new
Source:arXiv (Atom API + RSS)T1observed 52 min agohigh
arXiv id: 2609.11029
Source:arXiv (Atom API + RSS)T1observed 52 min agohigh
Categories: cs.CL, cs.LG
Source:arXiv (Atom API + RSS)T1observed 52 min agohigh
PDF: arxiv.org/pdf/2609.11029
Source:arXiv (Atom API + RSS)T1observed 52 min agohigh
Primary category: cs.CL
Source:arXiv (Atom API + RSS)T1observed 52 min agohigh
Published: 11 Sept 2026
Source:arXiv (Atom API + RSS)T1observed 52 min agohigh

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9

Source tiers

T19

Freshest observation

52 min ago

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None

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Authors: Zhijian Li, Stefan Larson, Kevin Leach

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Claim history for Categories
Value	Valid from → to	Status	Source	Confidence	Extractor
cs.CL, cs.LG	11 Sept 2026 21:02 UTC → current	current	arXiv (Atom API + RSS)T1	high	deterministic

Claims are temporal and append-only: a new observation closes the previous claim (valid_to) instead of overwriting it. Conflicting claims from different sources are kept side by side and flagged — never averaged. Methodology →

11 Sept 2026
Property changedPaperRebalancing Token Importance in Language Models with TF-IDF Weighted Cross-Entropy Loss
Rebalancing Token Importance in Language Models with TF-IDF Weighted Cross-Entropy Loss: arxiv announce type changed from cross to new
Arxiv announce typecross→newarxiv
rss.arxiv.org
11 Sept 2026
New paperPaperRebalancing Token Importance in Language Models with TF-IDF Weighted Cross-Entropy Loss
New paper: Rebalancing Token Importance in Language Models with TF-IDF Weighted Cross-Entropy Loss
arxiv
rss.arxiv.org

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Source documents
Source	Document	Type	Tier	Last observed	Snapshots
arXiv (Atom API + RSS)	rss.arxiv.org/rss/cs.CL	feed	T1· Official	52 min ago	1
arXiv (Atom API + RSS)	rss.arxiv.org/rss/cs.LG	feed	T1· Official	52 min ago	1

Tier 1 = official/primary, 2 = quality secondary, 3 = community, 4 = unverified. Every snapshot is archived; see all sources and the methodology.