Mind the truncation gap: challenges of learning on dynamic graphs with recurrent architectures

Fuente: arXiv
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Main Authors: Bravo, João, Bono, Jacopo, Saleiro, Pedro, Ferreira, Hugo, Bizarro, Pedro
Format: Preprint
Published: 2024
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author Bravo, João
Bono, Jacopo
Saleiro, Pedro
Ferreira, Hugo
Bizarro, Pedro
author_facet Bravo, João
Bono, Jacopo
Saleiro, Pedro
Ferreira, Hugo
Bizarro, Pedro
contents Systems characterized by evolving interactions, prevalent in social, financial, and biological domains, are effectively modeled as continuous-time dynamic graphs (CTDGs). To manage the scale and complexity of these graph datasets, machine learning (ML) approaches have become essential. However, CTDGs pose challenges for ML because traditional static graph methods do not naturally account for event timings. Newer approaches, such as graph recurrent neural networks (GRNNs), are inherently time-aware and offer advantages over static methods for CTDGs. However, GRNNs face another issue: the short truncation of backpropagation-through-time (BPTT), whose impact has not been properly examined until now. In this work, we demonstrate that this truncation can limit the learning of dependencies beyond a single hop, resulting in reduced performance. Through experiments on a novel synthetic task and real-world datasets, we reveal a performance gap between full backpropagation-through-time (F-BPTT) and the truncated backpropagation-through-time (T-BPTT) commonly used to train GRNN models. We term this gap the "truncation gap" and argue that understanding and addressing it is essential as the importance of CTDGs grows, discussing potential future directions for research in this area.
format Preprint
id arxiv_https___arxiv_org_abs_2412_21046
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Mind the truncation gap: challenges of learning on dynamic graphs with recurrent architectures
Bravo, João
Bono, Jacopo
Saleiro, Pedro
Ferreira, Hugo
Bizarro, Pedro
Machine Learning
Systems characterized by evolving interactions, prevalent in social, financial, and biological domains, are effectively modeled as continuous-time dynamic graphs (CTDGs). To manage the scale and complexity of these graph datasets, machine learning (ML) approaches have become essential. However, CTDGs pose challenges for ML because traditional static graph methods do not naturally account for event timings. Newer approaches, such as graph recurrent neural networks (GRNNs), are inherently time-aware and offer advantages over static methods for CTDGs. However, GRNNs face another issue: the short truncation of backpropagation-through-time (BPTT), whose impact has not been properly examined until now. In this work, we demonstrate that this truncation can limit the learning of dependencies beyond a single hop, resulting in reduced performance. Through experiments on a novel synthetic task and real-world datasets, we reveal a performance gap between full backpropagation-through-time (F-BPTT) and the truncated backpropagation-through-time (T-BPTT) commonly used to train GRNN models. We term this gap the "truncation gap" and argue that understanding and addressing it is essential as the importance of CTDGs grows, discussing potential future directions for research in this area.
title Mind the truncation gap: challenges of learning on dynamic graphs with recurrent architectures
topic Machine Learning
url https://arxiv.org/abs/2412.21046