Compute Allocation in Evolutionary Search: From Depth–Breadth to Multi-Armed Bandits

Sixue Xing, Haoyu He, Kerui Wu, Zhuo Yang, Haozheng Luo, Tianfan Fu, Aarthy Nagarajan


Abstract
LLM-guided evolutionary search (Evolve systems) has reached state-of-the-art results on mathematical and combinatorial tasks, yet most existing systems report only the best of many runs and leave the run-to-run distribution undocumented. We ask how a fixed budget of LLM calls should be allocated, and how reliably a single run reaches the reported numbers. Sweeping the depth–breadth grid over five models and three tasks, we identify two empirical regularities: a fitness–compute envelope along which capability ordering largely collapses on effective FLOPs, and a bilinear depth–breadth fit with task-specific interaction; both are gated by model–task capability. Motivated by these regularities, we propose BaSE (Bandit-based Self-Evolving), a multi-armed bandit that allocates LLM calls across parallel trajectories. Without changing the model, prompt, or evaluator, BaSE improves mean fitness by 12.3% over the strongest island-protocol baseline across 8 (model, task) cells, with the largest gains on high-variance settings: a reliability gain from allocation alone.
Anthology ID:
2026.emnlp-main.1056
Volume:
Proceedings of the 2026 Conference on Empirical Methods in Natural Language Processing
Month:
October
Year:
2026
Address:
Budapest, Hungary
Editors:
Hung-Yi Lee, Sunipa Dev, Jessy Li, Desmond Elliott
Venue:
EMNLP
SIG:
SIGDAT
Publisher:
Association for Computational Linguistics
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Pages:
24224–24251
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URL:
https://aclanthology.org/2026.emnlp-main.1056/
DOI:
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Cite (ACL):
Sixue Xing, Haoyu He, Kerui Wu, Zhuo Yang, Haozheng Luo, Tianfan Fu, and Aarthy Nagarajan. 2026. Compute Allocation in Evolutionary Search: From Depth–Breadth to Multi-Armed Bandits. In Proceedings of the 2026 Conference on Empirical Methods in Natural Language Processing, pages 24224–24251, Budapest, Hungary. Association for Computational Linguistics.
Cite (Informal):
Compute Allocation in Evolutionary Search: From Depth–Breadth to Multi-Armed Bandits (Xing et al., EMNLP 2026)
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PDF:
https://aclanthology.org/2026.emnlp-main.1056.pdf