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Memory$^3$: Language Modeling with Explicit Memory

Year:    2024

Author:    Hongkang Yang, Zehao Lin, Wenjin Wang, Hao Wu, Zhiyu Li, Bo Tang, Wenqiang Wei, Jinbo Wang, Zeyun Tang, Shichao Song, Chenyang Xi, Yu Yu, Kai Chen, Feiyu Xiong, Linpeng Tang, Weinan E

Journal of Machine Learning, Vol. 3 (2024), Iss. 3 : pp. 300–346

Abstract

The training and inference of large language models (LLMs) are together a costly process that transports knowledge from raw data to meaningful computation. Inspired by the memory hierarchy of the human brain, we reduce this cost by equipping LLMs with explicit memory, a memory format cheaper than model parameters and text retrieval-augmented generation (RAG). Conceptually, with most of its knowledge externalized to explicit memories, the LLM can enjoy a smaller parameter size, training cost, and inference cost, all proportional to the amount of remaining “abstract knowledge”. As a preliminary proof of concept, we train from scratch a 2.4 B LLM, which achieves better performance than much larger LLMs as well as RAG models, and maintains higher decoding speed than RAG. The model is named ${\rm Memory}^3$, since explicit memory is the third form of memory in LLMs after implicit memory (model parameters) and working memory (context key-values). We introduce a memory circuitry theory to support the externalization of knowledge, and present novel techniques including a memory sparsification mechanism that makes storage tractable and a two-stage pretraining scheme that facilitates memory formation.

Journal Article Details

Publisher Name:    Global Science Press

Language:    English

DOI:    https://doi.org/10.4208/jml.240708

Journal of Machine Learning, Vol. 3 (2024), Iss. 3 : pp. 300–346

Published online:    2024-01

AMS Subject Headings:   

Copyright:    COPYRIGHT: © Global Science Press

Pages:    47

Keywords:    Large language model Explicit memory Large-scale pretraining Efficient inference AI database.

Author Details

Hongkang Yang

Zehao Lin

Wenjin Wang

Hao Wu

Zhiyu Li

Bo Tang

Wenqiang Wei

Jinbo Wang

Zeyun Tang

Shichao Song

Chenyang Xi

Yu Yu

Kai Chen

Feiyu Xiong

Linpeng Tang

Weinan E