minnesotanlp/Finch-4B-KTO

VISIONPricing:Input $0.4 / Cached $0.08 / Output $0.8Concurrent Unit Cost:1Model Size:4.5BQuant:BF16Context Size:32kTool Calling:SupportedPublished:Jun 30, 2026License:apache-2.0Architecture:Transformer0.0K Open Weights Featherless Exclusive Cold

minnesotanlp/Finch-4B-KTO is a 4.5 billion parameter language model developed by minnesotanlp, built upon Qwen3.5-4B. It is specifically fine-tuned using Evolution Fine-Tuning (EFT) to act as a mutation operator for evolutionary search, enabling it to evolve solutions across diverse optimization tasks. Further enhanced with KTO preference learning, it gains the ability to self-judge solution quality, making it highly effective for discovery and problem-solving in complex domains like competitive programming and mathematical optimization.

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Overview of Finch-4B-KTO

Finch-4B-KTO is a 4.5 billion parameter model from the minnesotanlp Finch family, based on Qwen3.5-4B. It is uniquely designed for evolutionary search and problem discovery. The model undergoes a two-stage training process: first, Evolution Fine-Tuning (EFT) teaches it how to evolve solutions by acting as a mutation operator. Second, KTO (Kahneman-Tversky Optimization) preference learning is applied, enabling the model to self-judge the quality of candidate solutions, distinguishing between improvements and regressions.

Key Capabilities

  • Evolutionary Search Operator: Functions as a mutation operator within evolutionary scaffolds like OpenEvolve, proposing improved candidate programs.
  • Cross-Task Discovery: Learns to compose strategies across 371 diverse optimization tasks, moving discovery behavior into the model itself.
  • Self-Judgment of Solution Quality: Utilizes KTO to internalize a sense of solution quality, enhancing its ability to identify promising solutions.
  • Problem Solving: Excels in complex domains such as competitive programming (NP-hard problems), mathematical optimization (e.g., circle packing), and other discovery-oriented tasks.

Good For

  • Automated Program Improvement: When integrated with evolutionary scaffolds, it can iteratively refine and improve code or solutions.
  • Scientific Discovery: Tasks requiring the generation and evaluation of novel solutions in fields like mathematics, engineering, or computational science.
  • Competitive Programming: Outperforms base models on challenging competitive programming problems by composing diverse strategies.
  • Optimization Problems: Solving complex optimization tasks where iterative refinement and quality assessment are crucial.