Paper

Evolution Fine-Tuning: Learning to Discover Across 371 Optimization Tasks

Search traces become supervision: the model learns to propose the next mutation from task, parent, history, and feedback, then can be used with search or test-time RL.

arXiv ↗Jun 27, 2026Code ↗

  • llm
  • test-time optimization
  • supervised fine-tuning
  • evolutionary search

What it is

Mid-trains LLMs on evolutionary search traces so they learn reusable solution-improvement skills across optimization tasks instead of starting each task from scratch. Instead of leaving evolution skill in the search scaffold, EFT trains the model on search trajectories as next-mutation supervision, so smaller open LLMs internalize how to iteratively improve solutions across tasks.

Key results

  • +10.22% avg over base models on 22 held-out tasks
  • 355 training tasks vs 15 gives +14.1% avg held-out performance
  • Matches SOTA on 2 circle-packing tasks with test-time RL

Discovery strategies learned from many optimization problems can transfer across tasks and make smaller open LLMs stronger mutation operators.

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