Discovering Transformer Circuits via a Hybrid Attribution and Pruning Framework

Fuente: arXiv
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Main Authors: Gu, Hao, Nair, Vibhas, Kumar, Amrithaa Ashok, Sharma, Jayvart, Lagasse, Ryan
Format: Preprint
Published: 2025
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author Gu, Hao
Nair, Vibhas
Kumar, Amrithaa Ashok
Sharma, Jayvart
Lagasse, Ryan
author_facet Gu, Hao
Nair, Vibhas
Kumar, Amrithaa Ashok
Sharma, Jayvart
Lagasse, Ryan
contents Interpreting language models often involves circuit analysis, which aims to identify sparse subnetworks, or circuits, that accomplish specific tasks. Existing circuit discovery algorithms face a fundamental trade-off: attribution patching is fast but unfaithful to the full model, while edge pruning is faithful but computationally expensive. This research proposes a hybrid attribution and pruning (HAP) framework that uses attribution patching to identify a high-potential subgraph, then applies edge pruning to extract a faithful circuit from it. We show that HAP is 46\% faster than baseline algorithms without sacrificing circuit faithfulness. Furthermore, we present a case study on the Indirect Object Identification task, showing that our method preserves cooperative circuit components (e.g. S-inhibition heads) that attribution patching methods prune at high sparsity. Our results show that HAP could be an effective approach for improving the scalability of mechanistic interpretability research to larger models. Our code is available at https://anonymous.4open.science/r/HAP-circuit-discovery.
format Preprint
id arxiv_https___arxiv_org_abs_2510_03282
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Discovering Transformer Circuits via a Hybrid Attribution and Pruning Framework
Gu, Hao
Nair, Vibhas
Kumar, Amrithaa Ashok
Sharma, Jayvart
Lagasse, Ryan
Machine Learning
Computation and Language
I.2.6; I.2.7
Interpreting language models often involves circuit analysis, which aims to identify sparse subnetworks, or circuits, that accomplish specific tasks. Existing circuit discovery algorithms face a fundamental trade-off: attribution patching is fast but unfaithful to the full model, while edge pruning is faithful but computationally expensive. This research proposes a hybrid attribution and pruning (HAP) framework that uses attribution patching to identify a high-potential subgraph, then applies edge pruning to extract a faithful circuit from it. We show that HAP is 46\% faster than baseline algorithms without sacrificing circuit faithfulness. Furthermore, we present a case study on the Indirect Object Identification task, showing that our method preserves cooperative circuit components (e.g. S-inhibition heads) that attribution patching methods prune at high sparsity. Our results show that HAP could be an effective approach for improving the scalability of mechanistic interpretability research to larger models. Our code is available at https://anonymous.4open.science/r/HAP-circuit-discovery.
title Discovering Transformer Circuits via a Hybrid Attribution and Pruning Framework
topic Machine Learning
Computation and Language
I.2.6; I.2.7
url https://arxiv.org/abs/2510.03282