CCI4.0: A Bilingual Pretraining Dataset for Enhancing Reasoning in Large
  Language Models
Authors: name: Guang Liu; name: Liangdong Wang; name: Jijie Li; name: Yang Yu; name: Yao Xu; name: Jiabei Chen; name: Yu Bai; name: Feng Liao; name: Yonghua Lin
Published: 2025-06-09 06:14:19

Abstract: We introduce CCI4.0, a large-scale bilingual pre-training dataset engineered
for superior data quality and diverse human-like reasoning trajectory. CCI4.0
occupies roughly 35 TB of disk space and comprises two sub-datasets:
CCI4.0-M2-Base and CCI4.0-M2-CoT. CCI4.0-M2-Base combines a 5.2 TB carefully
curated Chinese web corpus, a 22.5 TB English subset from Nemotron-CC, and
diverse sources from math, wiki, arxiv, and code. Although these data are
mostly sourced from well-processed datasets, the quality standards of various
domains are dynamic and require extensive expert experience and labor to
process. So, we propose a novel pipeline justifying data quality mainly based
on models through two-stage deduplication, multiclassifier quality scoring, and
domain-aware fluency filtering. We extract 4.5 billion pieces of
CoT(Chain-of-Thought) templates, named CCI4.0-M2-CoT. Differing from the
distillation of CoT from larger models, our proposed staged CoT extraction
exemplifies diverse reasoning patterns and significantly decreases the
possibility of hallucination. Empirical evaluations demonstrate that LLMs
pre-trained in CCI4.0 benefit from cleaner, more reliable training signals,
yielding consistent improvements in downstream tasks, especially in math and
code reflection tasks. Our results underscore the critical role of rigorous
data curation and human thinking templates in advancing LLM performance,
shedding some light on automatically processing pretraining corpora.