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Pietro Lió

17 accepted papers

2026

Are Common Substructures Transferable? Understanding Transferability in Graph Pretraining under Riemannian Geometry

ICML 2026poster

Foundation models have sparked a revolution via a pretraining-adaptation paradigm, with recent efforts extending this success to graphs. Unlike other modalities, graphs contain rich structural patterns, yet their structural transferability remains poorly understood. Prior studies consider common sub…

Cited by 0SourceScholar
2026

Does a Hybrid Space-Aware Randomized Defense Improve Empirical and Certified Adversarial Robustness?

ICML 2026poster

We introduce Hybrid Space-aware Stochastic Convolution Attention Noise (HySCAN), a hybrid randomized defense that helps close the long-standing gap between provable robustness under ℓ2 certificates and empirical robustness against strong ℓ∞ attacks, while maintaining strong generalization across div…

Cited by 0SourceScholar
2026

Many Needles in a Haystack: Active Hit Discovery for Perturbation Experiments

ICML 2026poster

High-throughput gene perturbation experiments can test several genetic interventions in parallel, yet experimental budgets remain limited. A central goal is hit discovery: identifying as many perturbations as possible whose phenotypic effect exceeds a predefined threshold. Pure exploration strategie…

Cited by 0SourceScholar
2026

Towards Hierarchy–Uniformity Equilibrium: Recovering Semantic Depth in Hypergraph Contrastive Learning

ICML 2026oral

Hypergraph contrastive learning is an effective paradigm for representation learning on higher-order relational data, yet existing methods largely ignore that hyperedges link nodes with multi-level semantics. Standard contrastive objectives emphasize instance discrimination via hyperspherical unifor…

Cited by 0SourceScholar
2023

SurvivalGAN: Generating Time-to-Event Data for Survival Analysis

AISTATS 2023poster

Synthetic data is becoming an increasingly promising technology, and successful applications can improve privacy, fairness, and data democratization. While there are many methods for generating synthetic tabular data, the task remains non-trivial and unexplored for specific scenarios. One such scena…

2022

3D Infomax improves GNNs for Molecular Property Prediction

ICML 2022spotlight

Molecular property prediction is one of the fastest-growing applications of deep learning with critical real-world impacts. Although the 3D molecular graph structure is necessary for models to achieve strong performance on many tasks, it is infeasible to obtain 3D structures at the scale required by…

2022

Adaptive Gaussian Processes on Graphs via Spectral Graph Wavelets

AISTATS 2022poster

Graph-based models require aggregating information in the graph from neighbourhoods of different sizes. In particular, when the data exhibit varying levels of smoothness on the graph, a multi-scale approach is required to capture the relevant information. In this work, we propose a Gaussian process…

Cited by 26SourcePDFScholar
2022

Algorithmic Concept-Based Explainable Reasoning

AAAI 2022technical

Recent research on graph neural network (GNN) models successfully applied GNNs to classical graph algorithms and combinatorial optimisation problems. This has numerous benefits, such as allowing applications of algorithms when preconditions are not satisfied, or reusing learned models when sufficien…

2022

Attentional Meta-learners for Few-shot Polythetic Classification

ICML 2022spotlight

Polythetic classifications, based on shared patterns of features that need neither be universal nor constant among members of a class, are common in the natural world and greatly outnumber monothetic classifications over a set of features. We show that threshold meta-learners, such as Prototypical N…

2022

Entropy-Based Logic Explanations of Neural Networks

AAAI 2022technical

Explainable artificial intelligence has rapidly emerged since lawmakers have started requiring interpretable models for safety-critical domains. Concept-based neural networks have arisen as explainable-by-design methods as they leverage human-understandable symbols (i.e. concepts) to predict class m…

2021

Directional Graph Networks

ICML 2021oral

The lack of anisotropic kernels in graph neural networks (GNNs) strongly limits their expressiveness, contributing to well-known issues such as over-smoothing. To overcome this limitation, we propose the first globally consistent anisotropic kernels for GNNs, allowing for graph convolutions that are…

2021

How Framelets Enhance Graph Neural Networks

ICML 2021spotlight

This paper presents a new approach for assembling graph neural networks based on framelet transforms. The latter provides a multi-scale representation for graph-structured data. We decompose an input graph into low-pass and high-pass frequencies coefficients for network training, which then defines…

2021

Weisfeiler and Lehman Go Topological: Message Passing Simplicial Networks

ICML 2021spotlight

The pairwise interaction paradigm of graph machine learning has predominantly governed the modelling of relational systems. However, graphs alone cannot capture the multi-level interactions present in many complex systems and the expressive power of such schemes was proven to be limited. To overcome…

2020

Constraining Variational Inference with Geometric Jensen-Shannon Divergence

NeurIPS 2020poster

We examine the problem of controlling divergences for latent space regularisation in variational autoencoders. Specifically, when aiming to reconstruct example $x\in\mathbb{R}^{m}$ via latent space $z\in\mathbb{R}^{n}$ ($n\leq m$), while balancing this against the need for generalisable latent repre…

2020

On Second Order Behaviour in Augmented Neural ODEs

NeurIPS 2020poster

Neural Ordinary Differential Equations (NODEs) are a new class of models that transform data continuously through infinite-depth architectures. The continuous nature of NODEs has made them particularly suitable for learning the dynamics of complex physical systems. While previous work has mostly bee…

Cited by 116SourcePDFScholar