SWEA: Changing Factual Knowledge in Large Language Models via Subject Word Embedding Altering

Model editing has recently gained widespread attention. Current model editing methods primarily involve modifying model parameters or adding additional modules to the existing model. However, the former causes irreversible damage to Large Language Models (LLMs), while the latter incurs additional inference overhead and fuzzy vector matching is not always reliable. To address these issues, we propose an expandable Subject Word Embedding Altering (SWEA) framework, which finds the fused embeddings through character-level key-value matching and adds them to the subject word embeddings in Transformer input. To get these fused embeddings, we propose optimizing then suppressing fusion method, which first optimizes learnable embedding vectors for the editing target and then suppresses the Knowledge Embedding Dimensions (KEDs) to obtain final fused embeddings. We thus propose SWEA$\oplus$OS method for editing factual knowledge in LLMs. We demonstrate the overall state-of-the-art (SOTA) performance of SWEA$\oplus$OS on the COUNTERFACT and zsRE datasets. To further validate the reasoning ability of SWEA$\oplus$OS in editing knowledge, we evaluate it on the more complex RippleEdits benchmark. The results demonstrate that SWEA$\oplus$OS possesses SOTA reasoning ability.