MachineLearningLM: Continued Pretraining Language Models on Millions of
  Synthetic Tabular Prediction Tasks Scales In-Context ML
Authors: name: Haoyu Dong; name: Pengkun Zhang; name: Mingzhe Lu; name: Yanzhen Shen; name: Guolin Ke
Published: 2025-09-08 15:38:31

Abstract: Large language models (LLMs) possess broad world knowledge and strong
general-purpose reasoning ability, yet they struggle to learn from many
in-context examples on standard machine learning (ML) tasks, that is, to
leverage many-shot demonstrations purely via in-context learning (ICL) without
gradient descent. We introduce MachineLearningLM, a portable
continued-pretraining framework that equips a general-purpose LLM with robust
in-context ML capability while preserving its general knowledge and reasoning
for broader chat workflows.
  Our pretraining procedure synthesizes ML tasks from millions of structural
causal models (SCMs), spanning shot counts up to 1,024. We begin with a
random-forest teacher, distilling tree-based decision strategies into the LLM
to strengthen robustness in numerical modeling. All tasks are serialized with a
token-efficient prompt, enabling 3x to 6x more examples per context window and
delivering up to 50x amortized throughput via batch inference.
  Despite a modest setup (Qwen-2.5-7B-Instruct with LoRA rank 8),
MachineLearningLM outperforms strong LLM baselines (e.g., GPT-5-mini) by an
average of about 15% on out-of-distribution tabular classification across
finance, physics, biology, and healthcare domains. It exhibits a striking
many-shot scaling law: accuracy increases monotonically as in-context
demonstrations grow from 8 to 1,024. Without any task-specific training, it
attains random-forest-level accuracy across hundreds of shots. General chat
capabilities, including knowledge and reasoning, are preserved: it achieves
75.4% on MMLU.