Recently, large language models (LLMs) have exhibited significant progress in
language understanding and generation. By leveraging textual features,
customized LLMs are also applied for recommendation and demonstrate
improvements across diverse recommendation scenarios. Yet the majority of
existing methods perform training-free recommendation that heavily relies on
pretrained knowledge (e.g., movie recommendation). In addition, inference on
LLMs is slow due to autoregressive generation, rendering existing methods less
effective for real-time recommendation. As such, we propose a two-stage
framework using large language models for ranking-based recommendation
(LlamaRec). In particular, we use small-scale sequential recommenders to
retrieve candidates based on the user interaction history. Then, both history
and retrieved items are fed to the LLM in text via a carefully designed prompt
template. Instead of generating next-item titles, we adopt a verbalizer-based
approach that transforms output logits into probability distributions over the
candidate items. Therefore, the proposed LlamaRec can efficiently rank items
without generating long text. To validate the effectiveness of the proposed
framework, we compare against state-of-the-art baseline methods on benchmark
datasets. Our experimental results demonstrate the performance of LlamaRec,
which consistently achieves superior performance in both recommendation
performance and efficiency.

最近，大型语言模型 (LLMs) 在语言理解和生成方面取得了显著的进展，通过利用文本特征，定制 LLMs 也被应用于推荐，并在各种推荐场景中展示出改进。为了验证所提出框架的有效性，在基准数据集上与最先进的基线方法进行比较，我们的实验结果证明了 LlamaRec 的性能，在推荐性能和效率方面都取得了卓越的表现。