From RAG to Memory: Non-Parametric Continual Learning for Large Language
  Models
Authors: name: Bernal Jiménez Gutiérrez; name: Yiheng Shu; name: Weijian Qi; name: Sizhe Zhou; name: Yu Su
Published: 2025-02-20 18:26:02

Abstract: Our ability to continuously acquire, organize, and leverage knowledge is a
key feature of human intelligence that AI systems must approximate to unlock
their full potential. Given the challenges in continual learning with large
language models (LLMs), retrieval-augmented generation (RAG) has become the
dominant way to introduce new information. However, its reliance on vector
retrieval hinders its ability to mimic the dynamic and interconnected nature of
human long-term memory. Recent RAG approaches augment vector embeddings with
various structures like knowledge graphs to address some of these gaps, namely
sense-making and associativity. However, their performance on more basic
factual memory tasks drops considerably below standard RAG. We address this
unintended deterioration and propose HippoRAG 2, a framework that outperforms
standard RAG comprehensively on factual, sense-making, and associative memory
tasks. HippoRAG 2 builds upon the Personalized PageRank algorithm used in
HippoRAG and enhances it with deeper passage integration and more effective
online use of an LLM. This combination pushes this RAG system closer to the
effectiveness of human long-term memory, achieving a 7% improvement in
associative memory tasks over the state-of-the-art embedding model while also
exhibiting superior factual knowledge and sense-making memory capabilities.
This work paves the way for non-parametric continual learning for LLMs. Our
code and data will be released at https://github.com/OSU-NLP-Group/HippoRAG.