WISE: Rethinking the Knowledge Memory for Lifelong Model Editing of Large Language Models

AuthorsPeng Wang, Zexi Li, Ningyu Zhang et al.

arXiv 20242024

TL;DR

WISE uses a dual parametric memory with side memory plus knowledge sharding and Ties-Merge routing to achieve 0.90 average reliability, generalization, and locality on ZsRE at T = 100 edits, beating MEMIT-MASS by 0.14.

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THE PROBLEM

Lifelong edits break reliability, generalization, and locality together

WISE shows that editing either long term memory or working memory alone creates an impossible triangle where reliability, generalization, and locality cannot all be high.

On ZsRE with 100 continual edits, long term editors like ROME and FT-EWC lose locality, while working memory editors like GRACE lose generalization, degrading real world QA updates.

HOW IT WORKS

WISE — Dual parametric memory with routing and sharded merging

WISE builds a dual parametric memory using a Side Memory copied from the FFN value matrix, plus Main Memory, Memory Routing, and Knowledge Sharding and Merging modules.

You can think of WISE like a brain with a stable cortex for pretrained knowledge and a separate mid term region that accumulates edits, connected by a learned router instead of a single shared weight matrix.

This design lets WISE keep pretrained behavior intact while routing only edited queries through dense sharded subspaces, something a plain context window or single parameter space cannot provide.

DIAGRAM

WISE Inference Flow with Activation Based Routing

This diagram shows how WISE routes each query between main and side memory using the activation indicator Δact(x) and threshold ϵ during inference.

DIAGRAM

WISE Training and Evaluation Pipeline for Lifelong Editing

This diagram shows how WISE trains side memory with sharded edits, merges subspaces, and evaluates reliability, generalization, and locality on ZsRE.

PROCESS

How WISE Handles a Lifelong Model Editing Stream

  1. 01

    Side Memory Design

    WISE initializes Side Memory by copying the FFN value matrix Wv into Wv′ at a mid to late layer, separating pretrained and edited knowledge.

  2. 02

    Routing Between Side Memories and Main Memory

    WISE uses Memory Routing with the activation indicator Δact(x) and margin based loss La to learn when to send queries through side memory versus main memory.

  3. 03

    Knowledge in Random Memory Subspaces

    WISE applies Knowledge Sharding by generating random gradient masks Mi with ratio ρ and training k side memory copies on different edit shards.

  4. 04

    Knowledge Merging

    WISE performs Knowledge Merging using Ties-Merge on edit vectors τe to combine subspace memories into one side memory while preserving previous edits.

KEY CONTRIBUTIONS

Key Contributions

  • 01

    Impossible Triangle of Lifelong Model Editing

    WISE identifies that editing only long term or working memory yields an impossible triangle where reliability, generalization, and locality cannot all be high in continual settings.

  • 02

    WISE Dual Parametric Memory Scheme

    WISE introduces a Side Memory plus Memory Routing design that stores edits in a separate FFN value matrix and routes queries by Δact(x), achieving mid term memory behavior.

  • 03

    Knowledge Sharding and Merging Mechanism

    WISE proposes Knowledge Sharding and Merging with random subspace masks and Ties-Merge, showing that 20% FFN parameters can store at least 500 edits without conflicts.

RESULTS

By the Numbers

Avg. (ZsRE T=100 LLaMA-2-7B)

0.90

+0.14 over MEMIT-MASS

Rel. (ZsRE T=100 LLaMA-2-7B)

0.90

+0.14 over MEMIT-MASS

Gen. (ZsRE T=100 LLaMA-2-7B)

0.81

+0.13 over MEMIT-MASS

Loc. (ZsRE T=100 LLaMA-2-7B)

1.00

+0.15 over MEMIT-MASS

These numbers come from the ZsRE QA benchmark under T = 100 continual edits on LLaMA-2-7B, which tests reliability, paraphrase generalization, and locality. The MAIN_RESULT shows that WISE simultaneously maintains 0.90 average score and 1.00 locality, while MEMIT-MASS reaches only 0.76 average and 0.85 locality.

BENCHMARK

By the Numbers

These numbers come from the ZsRE QA benchmark under T = 100 continual edits on LLaMA-2-7B, which tests reliability, paraphrase generalization, and locality. The MAIN_RESULT shows that WISE simultaneously maintains 0.90 average score and 1.00 locality, while MEMIT-MASS reaches only 0.76 average and 0.85 locality.

BENCHMARK

Main editing results for QA setting (ZsRE dataset), LLaMA-2-7B, T = 100

Average score (Rel., Gen., Loc. mean) on ZsRE with 100 continual edits for LLaMA-2-7B.

KEY INSIGHT

The Counterintuitive Finding

WISE shows that a side memory using only 20% of FFN parameters can handle at least 500 edits while keeping locality at 1.00.

This is surprising because many assume more edited parameters always help, but WISE finds that higher knowledge density in small subspaces can improve generalization instead of causing overfitting.

WHY IT MATTERS

What this unlocks for the field

WISE unlocks a practical way to perform thousands of edits on deployed LLMs while preserving pretrained behavior and paraphrase generalization.

Builders can now maintain a stable base model and plug in discardable side memories for different domains or time periods, enabling safer, reversible, and lifelong model editing without full retraining.

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