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Main Authors: Gaurav, Gaurav, ALJabea, Ibrahem, Zakomornyy, Yaroslav, Frank, Eric, Elhamdadi, Mohamed, Papamarkou, Theodore, Hajij, Mustafa
Format: Preprint
Published: 2026
Subjects:
Online Access:https://arxiv.org/abs/2605.10091
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author Gaurav, Gaurav
ALJabea, Ibrahem
Zakomornyy, Yaroslav
Frank, Eric
Elhamdadi, Mohamed
Papamarkou, Theodore
Hajij, Mustafa
author_facet Gaurav, Gaurav
ALJabea, Ibrahem
Zakomornyy, Yaroslav
Frank, Eric
Elhamdadi, Mohamed
Papamarkou, Theodore
Hajij, Mustafa
contents Many modern datasets mix points, edges, regions, groups, objects, events, hyperedges, and relations. Yet neural architectures often force such data into grids, graphs, or sequences, obscuring higher-order structure and making encoder-decoder designs domain-specific. We view U-Net not as a grid-specific architecture, but as a hierarchical encoder-decoder principle: representation spaces, transport maps between levels, and skip connections between matched levels. Combinatorial complexes naturally supply these ingredients through cells, incidences, and ranks. We introduce TopoU-Net, a rank-path U-Net for topological domains. Given a path from an input rank to a bottleneck rank and back, the encoder lifts cochains upward along incidence maps, the decoder transports them downward, and skip connections merge features at matched ranks. Rank replaces spatial scale: choosing paths through nodes, edges, faces, hyperedges, or global cells becomes the central architectural decision. A key quantity is the bottleneck support ratio, the number of cells at the bottleneck relative to the number of cells at the input rank. This ratio is fixed by the complex and chosen path rather than by arbitrary pooling, and it clarifies when skip connections are optional, useful, or structurally important. Across node classification, graph classification, hypergraph node classification, mesh classification, and image reconstruction, TopoU-Net provides a reusable encoder-decoder template for higher-order structured data. Among the evaluated baselines, it achieves the strongest mean accuracy on six of eight node-classification datasets and four of five hypergraph datasets, with the largest gains on heterophilic graphs. Ablations show that removing skip connections is most damaging under severe bottleneck compression.
format Preprint
id arxiv_https___arxiv_org_abs_2605_10091
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle TopoU-Net: a U-Net architecture for topological domains
Gaurav, Gaurav
ALJabea, Ibrahem
Zakomornyy, Yaroslav
Frank, Eric
Elhamdadi, Mohamed
Papamarkou, Theodore
Hajij, Mustafa
Machine Learning
Many modern datasets mix points, edges, regions, groups, objects, events, hyperedges, and relations. Yet neural architectures often force such data into grids, graphs, or sequences, obscuring higher-order structure and making encoder-decoder designs domain-specific. We view U-Net not as a grid-specific architecture, but as a hierarchical encoder-decoder principle: representation spaces, transport maps between levels, and skip connections between matched levels. Combinatorial complexes naturally supply these ingredients through cells, incidences, and ranks. We introduce TopoU-Net, a rank-path U-Net for topological domains. Given a path from an input rank to a bottleneck rank and back, the encoder lifts cochains upward along incidence maps, the decoder transports them downward, and skip connections merge features at matched ranks. Rank replaces spatial scale: choosing paths through nodes, edges, faces, hyperedges, or global cells becomes the central architectural decision. A key quantity is the bottleneck support ratio, the number of cells at the bottleneck relative to the number of cells at the input rank. This ratio is fixed by the complex and chosen path rather than by arbitrary pooling, and it clarifies when skip connections are optional, useful, or structurally important. Across node classification, graph classification, hypergraph node classification, mesh classification, and image reconstruction, TopoU-Net provides a reusable encoder-decoder template for higher-order structured data. Among the evaluated baselines, it achieves the strongest mean accuracy on six of eight node-classification datasets and four of five hypergraph datasets, with the largest gains on heterophilic graphs. Ablations show that removing skip connections is most damaging under severe bottleneck compression.
title TopoU-Net: a U-Net architecture for topological domains
topic Machine Learning
url https://arxiv.org/abs/2605.10091