Align-Pro: A Principled Approach to Prompt Optimization for LLM Alignment
This work addresses the alignment challenge for LLMs in societal applications, offering a practical solution when fine-tuning is infeasible, though it is incremental as it builds on existing prompt optimization ideas.
The paper tackles the problem of aligning large language models with human values by proposing prompt optimization as an alternative to computationally expensive methods like RLHF, showing through theoretical analysis and experiments that it can effectively align LLMs even when model parameters are frozen.
The alignment of large language models (LLMs) with human values is critical as these models become increasingly integrated into various societal and decision-making processes. Traditional methods, such as reinforcement learning from human feedback (RLHF), achieve alignment by fine-tuning model parameters, but these approaches are often computationally expensive and impractical when models are frozen or inaccessible for parameter modification. In contrast, prompt optimization is a viable alternative to RLHF for LLM alignment. While the existing literature has shown empirical promise of prompt optimization, its theoretical underpinning remains under-explored. We address this gap by formulating prompt optimization as an optimization problem and try to provide theoretical insights into the optimality of such a framework. To analyze the performance of the prompt optimization, we study theoretical suboptimality bounds and provide insights in terms of how prompt optimization depends upon the given prompter and target model. We also provide empirical validation through experiments on various datasets, demonstrating that prompt optimization can effectively align LLMs, even when parameter fine-tuning is not feasible.