Tree-of-Prompts: Abstracting Control-Flow for Prompt Optimization

Prompt optimization (PO) generates prompts to guide Large Language Models (LLMs) in performing tasks. Existing methods, such as PromptAgent, rely on a single static prompt, which struggles with disjoint cases in complex tasks. Although Mixture-of-Prompts (MoP) uses multiple prompts, it fails to account for variations in task complexity. Inspired by programmatic control flow, we introduce a nested if-else structure to address both varying similarities and complexities across diverse cases. We propose Tree-of-Prompts (ToP), which recursively expands child prompts from a parent prompt. Sibling prompts tackle disjoint cases while inheriting shared similarities from their parent, and handle cases more complex than the parent. Evaluated on Gorilla (understanding), MATH (reasoning), and a subset of BBH benchmarks, ToP outperforms PromptAgent and MoP, with improvements of 1.4% and 4.6% over PromptAgent and 3.2% and 4.5% over MoP, when tested with GPT-4o-mini and Llama 3.2-3B, respectively.