Connecting Large Language Models with Evolutionary Algorithms Yields
  Powerful Prompt Optimizers
Authors: name: Qingyan Guo, name: Rui Wang, name: Junliang Guo, name: Bei Li, name: Kaitao Song, name: Xu Tan, name: Guoqing Liu, name: Jiang Bian, name: Yujiu Yang

Large Language Models (LLMs) excel in various tasks, but they rely on
carefully crafted prompts that often demand substantial human effort. To
automate this process, in this paper, we propose a novel framework for discrete
prompt optimization, called EvoPrompt, which borrows the idea of evolutionary
algorithms (EAs) as they exhibit good performance and fast convergence. To
enable EAs to work on discrete prompts, which are natural language expressions
that need to be coherent and human-readable, we connect LLMs with EAs. This
approach allows us to simultaneously leverage the powerful language processing
capabilities of LLMs and the efficient optimization performance of EAs.
Specifically, abstaining from any gradients or parameters, EvoPrompt starts
from a population of prompts and iteratively generates new prompts with LLMs
based on the evolutionary operators, improving the population based on the
development set. We optimize prompts for both closed- and open-source LLMs
including GPT-3.5 and Alpaca, on 9 datasets spanning language understanding and
generation tasks. EvoPrompt significantly outperforms human-engineered prompts
and existing methods for automatic prompt generation by up to 25% and 14%
respectively. Furthermore, EvoPrompt demonstrates that connecting LLMs with EAs
creates synergies, which could inspire further research on the combination of
LLMs and conventional algorithms.