Topological Blindspots: Understanding and Extending Topological Deep Learning Through the Lens of Expressivity

Fuente: arXiv
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Main Authors: Eitan, Yam, Gelberg, Yoav, Bar-Shalom, Guy, Frasca, Fabrizio, Bronstein, Michael, Maron, Haggai
Format: Preprint
Published: 2024
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author Eitan, Yam
Gelberg, Yoav
Bar-Shalom, Guy
Frasca, Fabrizio
Bronstein, Michael
Maron, Haggai
author_facet Eitan, Yam
Gelberg, Yoav
Bar-Shalom, Guy
Frasca, Fabrizio
Bronstein, Michael
Maron, Haggai
contents Topological deep learning (TDL) is a rapidly growing field that seeks to leverage topological structure in data and facilitate learning from data supported on topological objects, ranging from molecules to 3D shapes. Most TDL architectures can be unified under the framework of higher-order message-passing (HOMP), which generalizes graph message-passing to higher-order domains. In the first part of the paper, we explore HOMP's expressive power from a topological perspective, demonstrating the framework's inability to capture fundamental topological and metric invariants such as diameter, orientability, planarity, and homology. In addition, we demonstrate HOMP's limitations in fully leveraging lifting and pooling methods on graphs. To the best of our knowledge, this is the first work to study the expressivity of TDL from a \emph{topological} perspective. In the second part of the paper, we develop two new classes of architectures -- multi-cellular networks (MCN) and scalable MCN (SMCN) -- which draw inspiration from expressive GNNs. MCN can reach full expressivity, but scaling it to large data objects can be computationally expansive. Designed as a more scalable alternative, SMCN still mitigates many of HOMP's expressivity limitations. Finally, we create new benchmarks for evaluating models based on their ability to learn topological properties of complexes. We then evaluate SMCN on these benchmarks and on real-world graph datasets, demonstrating improvements over both HOMP baselines and expressive graph methods, highlighting the value of expressively leveraging topological information. Code and data are available at https://github.com/yoavgelberg/SMCN.
format Preprint
id arxiv_https___arxiv_org_abs_2408_05486
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Topological Blindspots: Understanding and Extending Topological Deep Learning Through the Lens of Expressivity
Eitan, Yam
Gelberg, Yoav
Bar-Shalom, Guy
Frasca, Fabrizio
Bronstein, Michael
Maron, Haggai
Machine Learning
Algebraic Topology
Topological deep learning (TDL) is a rapidly growing field that seeks to leverage topological structure in data and facilitate learning from data supported on topological objects, ranging from molecules to 3D shapes. Most TDL architectures can be unified under the framework of higher-order message-passing (HOMP), which generalizes graph message-passing to higher-order domains. In the first part of the paper, we explore HOMP's expressive power from a topological perspective, demonstrating the framework's inability to capture fundamental topological and metric invariants such as diameter, orientability, planarity, and homology. In addition, we demonstrate HOMP's limitations in fully leveraging lifting and pooling methods on graphs. To the best of our knowledge, this is the first work to study the expressivity of TDL from a \emph{topological} perspective. In the second part of the paper, we develop two new classes of architectures -- multi-cellular networks (MCN) and scalable MCN (SMCN) -- which draw inspiration from expressive GNNs. MCN can reach full expressivity, but scaling it to large data objects can be computationally expansive. Designed as a more scalable alternative, SMCN still mitigates many of HOMP's expressivity limitations. Finally, we create new benchmarks for evaluating models based on their ability to learn topological properties of complexes. We then evaluate SMCN on these benchmarks and on real-world graph datasets, demonstrating improvements over both HOMP baselines and expressive graph methods, highlighting the value of expressively leveraging topological information. Code and data are available at https://github.com/yoavgelberg/SMCN.
title Topological Blindspots: Understanding and Extending Topological Deep Learning Through the Lens of Expressivity
topic Machine Learning
Algebraic Topology
url https://arxiv.org/abs/2408.05486