Massive Activations in Graph Neural Networks: Decoding Attention for Domain-Dependent Interpretability

Fuente: arXiv
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Autores principales: Bini, Lorenzo, Sorbi, Marco, Marchand-Maillet, Stephane
Formato: Preprint
Publicado: 2024
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author Bini, Lorenzo
Sorbi, Marco
Marchand-Maillet, Stephane
author_facet Bini, Lorenzo
Sorbi, Marco
Marchand-Maillet, Stephane
contents Graph Neural Networks (GNNs) have become increasingly popular for effectively modeling graph-structured data, and attention mechanisms have been pivotal in enabling these models to capture complex patterns. In our study, we reveal a critical yet underexplored consequence of integrating attention into edge-featured GNNs: the emergence of Massive Activations (MAs) within attention layers. By developing a novel method for detecting MAs on edge features, we show that these extreme activations are not only activation anomalies but encode domain-relevant signals. Our post-hoc interpretability analysis demonstrates that, in molecular graphs, MAs aggregate predominantly on common bond types (e.g., single and double bonds) while sparing more informative ones (e.g., triple bonds). Furthermore, our ablation studies confirm that MAs can serve as natural attribution indicators, reallocating to less informative edges. Our study assesses various edge-featured attention-based GNN models using benchmark datasets, including ZINC, TOX21, and PROTEINS. Key contributions include (1) establishing the direct link between attention mechanisms and MAs generation in edge-featured GNNs, (2) developing a robust definition and detection method for MAs enabling reliable post-hoc interpretability. Overall, our study reveals the complex interplay between attention mechanisms, edge-featured GNNs model, and MAs emergence, providing crucial insights for relating GNNs internals to domain knowledge.
format Preprint
id arxiv_https___arxiv_org_abs_2409_03463
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Massive Activations in Graph Neural Networks: Decoding Attention for Domain-Dependent Interpretability
Bini, Lorenzo
Sorbi, Marco
Marchand-Maillet, Stephane
Machine Learning
Artificial Intelligence
Graph Neural Networks (GNNs) have become increasingly popular for effectively modeling graph-structured data, and attention mechanisms have been pivotal in enabling these models to capture complex patterns. In our study, we reveal a critical yet underexplored consequence of integrating attention into edge-featured GNNs: the emergence of Massive Activations (MAs) within attention layers. By developing a novel method for detecting MAs on edge features, we show that these extreme activations are not only activation anomalies but encode domain-relevant signals. Our post-hoc interpretability analysis demonstrates that, in molecular graphs, MAs aggregate predominantly on common bond types (e.g., single and double bonds) while sparing more informative ones (e.g., triple bonds). Furthermore, our ablation studies confirm that MAs can serve as natural attribution indicators, reallocating to less informative edges. Our study assesses various edge-featured attention-based GNN models using benchmark datasets, including ZINC, TOX21, and PROTEINS. Key contributions include (1) establishing the direct link between attention mechanisms and MAs generation in edge-featured GNNs, (2) developing a robust definition and detection method for MAs enabling reliable post-hoc interpretability. Overall, our study reveals the complex interplay between attention mechanisms, edge-featured GNNs model, and MAs emergence, providing crucial insights for relating GNNs internals to domain knowledge.
title Massive Activations in Graph Neural Networks: Decoding Attention for Domain-Dependent Interpretability
topic Machine Learning
Artificial Intelligence
url https://arxiv.org/abs/2409.03463