SynDec: A Synthesize-then-Decode Approach for Arbitrary Textual Style Transfer via Large Language Models

TL;DR

SynDec introduces an automatic prompt synthesis and amplification method for arbitrary textual style transfer using LLMs, significantly improving transfer accuracy across multiple benchmarks.

Contribution

It proposes a novel Synthesize-then-Decode approach that automatically generates prompts and enhances decoding, addressing manual prompt reliance and stylistic biases in LLMs.

Findings

Outperforms state-of-the-art methods on five of six benchmarks

Achieves up to 9% accuracy increase in style transfer tasks

Validated through extensive ablation studies

Abstract

Large Language Models (LLMs) are emerging as dominant forces for textual style transfer. However, for arbitrary style transfer, LLMs face two key challenges: (1) considerable reliance on manually-constructed prompts and (2) rigid stylistic biases inherent in LLMs. In this paper, we propose a novel Synthesize-then-Decode (SynDec) approach, which automatically synthesizes high-quality prompts and amplifies their roles during decoding process. Specifically, our approach synthesizes prompts by selecting representative few-shot samples, conducting a four-dimensional style analysis, and reranking the candidates. At LLM decoding stage, the TST effect is amplified by maximizing the contrast in output probabilities between scenarios with and without the synthesized prompt, as well as between prompts and negative samples. We conduct extensive experiments and the results show that SynDec outperforms existing state-of-the-art LLM-based methods on five out of six benchmarks (e.g., achieving up to a 9\% increase in accuracy for modern-to-Elizabethan English transfer). Detailed ablation studies further validate the effectiveness of SynDec.