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Johannes F. Lutzeyer

11 accepted papers

2026

Graph Representational Learning: When Does More Expressivity Hurt Generalization?

ICLR 2026poster

Graph Neural Networks (GNNs) are powerful tools for learning on structured data, yet the relationship between their expressivity and predictive performance remains unclear. We introduce a family of pseudometrics that capture different degrees of structural similarity between graphs and relate these…

Cited by 0SourcecodeScholar
2025

Enhancing Graph Classification Robustness with Singular Pooling

NeurIPS 2025poster

Graph Neural Networks (GNNs) have achieved strong performance across a range of graph representation learning tasks, yet their adversarial robustness in graph classification remains underexplored compared to node classification. While most existing defenses focus on the message-passing component, th…

Cited by 0SourceScholar
2025

Graph Neural Network Generalization With Gaussian Mixture Model Based Augmentation

ICML 2025poster

Graph Neural Networks (GNNs) have shown great promise in tasks like node and graph classification, but they often struggle to generalize, particularly to unseen or out-of-distribution (OOD) data. These challenges are exacerbated when training data is limited in size or diversity. To address these is…

Cited by 0SourcePDFScholar
2025

Speeding Up Hyper-Heuristics With Markov-Chain Operator Selection and the Only-Worsening Acceptance Operator

IJCAI 2025

The move-acceptance hyper-heuristic was recently shown to be able to leave local optima with astonishing efficiency (Lissovoi et al., Artificial Intelligence (2023)). In this work, we propose two modifications to this algorithm that demonstrate impressive performances on a large class of benchmarks

Cited by 0SourcePDFScholar
2025

Understanding Virtual Nodes: Oversquashing and Node Heterogeneity

ICLR 2025poster

While message passing neural networks (MPNNs) have convincing success in a range of applications, they exhibit limitations such as the oversquashing problem and their inability to capture long-range interactions. Augmenting MPNNs with a virtual node (VN) removes the locality constraint of the layer…

Cited by 0SourcePDFScholar
2024

A Simple and Yet Fairly Effective Defense for Graph Neural Networks

AAAI 2024technical

Graph Neural Networks (GNNs) have emerged as the dominant approach for machine learning on graph-structured data. However, concerns have arisen regarding the vulnerability of GNNs to small adversarial perturbations. Existing defense methods against such perturbations suffer from high time complexity…

2024

Bounding the Expected Robustness of Graph Neural Networks Subject to Node Feature Attacks

ICLR 2024poster

Graph Neural Networks (GNNs) have demonstrated state-of-the-art performance in various graph representation learning tasks. Recently, studies revealed their vulnerability to adversarial attacks. In this work, we theoretically define the concept of expected robustness in the context of attributed gra…

2024

If You Want to Be Robust, Be Wary of Initialization

NeurIPS 2024poster

Graph Neural Networks (GNNs) have demonstrated remarkable performance across a spectrum of graph-related tasks, however concerns persist regarding their vulnerability to adversarial perturbations. While prevailing defense strategies focus primarily on pre-processing techniques and adaptive message-p…

Cited by 1SourcePDFScholar
2023

Path Neural Networks: Expressive and Accurate Graph Neural Networks

ICML 2023poster

Graph neural networks (GNNs) have recently become the standard approach for learning with graph-structured data. Prior work has shed light into their potential, but also their limitations. Unfortunately, it was shown that standard GNNs are limited in their expressive power. These models are no more…

2022

Node Feature Kernels Increase Graph Convolutional Network Robustness

AISTATS 2022poster

The robustness of the much used Graph Convolutional Networks (GCNs) to perturbations of their input is becoming a topic of increasing importance. In this paper the random GCN is introduced for which a random matrix theory analysis is possible. This analysis suggests that if the graph is sufficiently…

2021

Learning Parametrised Graph Shift Operators

ICLR 2021poster

In many domains data is currently represented as graphs and therefore, the graph representation of this data becomes increasingly important in machine learning. Network data is, implicitly or explicitly, always represented using a graph shift operator (GSO) with the most common choices being the adj…