MORE-FE: Multi-Operator and Reinforcement Learning-Enhanced Evolution for LLM Feature Engineering

Traditional automated feature engineering (AFE) minimizes human intervention but often neglects semantic relationships among original features, resulting in redundant or uninterpretable transformations. While recent methods leverage the domain knowledge and reasoning capabilities of Large Language Models (LLMs), they typically constrain the search space via predefined mathematical operators or suffer from poor exploration-exploitation balance due to exclusive reliance on validation feedback. To address these limitations, we propose MORE-FE, an evolutionary AFE framework that integrates multi-operator exploration with Reinforcement Learning with Verifiable Rewards (RLVR). MORE-FE treats feature transformation programs as hypotheses and evolves them using evolutionary operators that explore semantically coherent and logically structured features through various prompting strategies. Moreover, it employs RLVR to align LLM reasoning with structured evolutionary exploration using a composite reward that balances quality and diversity. Extensive experiments on multiple classification and regression datasets demonstrate that MORE-FE consistently outperforms state-of-the-art AFE methods, highlighting the effectiveness of balancing quality and diversity in feature engineering.