With large language models (LLMs) achieving remarkable breakthroughs in
natural language processing (NLP) domains, LLM-enhanced recommender systems
have received much attention and have been actively explored currently. In this
paper, we focus on adapting and empowering a pure large language model for
zero-shot and few-shot recommendation tasks. First and foremost, we identify
and formulate the lifelong sequential behavior incomprehension problem for LLMs
in recommendation domains, i.e., LLMs fail to extract useful information from a
textual context of long user behavior sequence, even if the length of context
is far from reaching the context limitation of LLMs. To address such an issue
and improve the recommendation performance of LLMs, we propose a novel
framework, namely Retrieval-enhanced Large Language models (ReLLa) for
recommendation tasks in both zero-shot and few-shot settings. For zero-shot
recommendation, we perform semantic user behavior retrieval (SUBR) to improve
the data quality of testing samples, which greatly reduces the difficulty for
LLMs to extract the essential knowledge from user behavior sequences. As for
few-shot recommendation, we further design retrieval-enhanced instruction
tuning (ReiT) by adopting SUBR as a data augmentation technique for training
samples. Specifically, we develop a mixed training dataset consisting of both
the original data samples and their retrieval-enhanced counterparts. We conduct
extensive experiments on a real-world public dataset (i.e., MovieLens-1M) to
demonstrate the superiority of ReLLa compared with existing baseline models, as
well as its capability for lifelong sequential behavior comprehension.

我们提出了一种名为 ReLLa 的新框架，即检索增强的大型语言模型，用于零样本和少样本推荐任务，通过语义用户行为检索和检索增强指导调优技术，提高了大型语言模型在推荐系统中的推荐性能和对用户行为序列的理解能力。