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Bruno Ribeiro

27 accepted papers

2026

Bridging Input Feature Spaces Towards Graph Foundation Models

ICLR 2026poster

Unlike vision and language domains, graph learning lacks a shared input space, as input features differ across graph datasets not only in semantics, but also in value ranges and dimensionality. This misalignment prevents graph models from generalizing across datasets, limiting their use as foundatio…

Cited by 0SourcecodeScholar
2026

Membership Inference Attacks Against Fine-tuned Diffusion Language Models

ICLR 2026poster

Diffusion Language Models (DLMs) represent a promising alternative to autoregressive language models, using bidirectional masked token prediction. Yet their susceptibility to privacy leakage via Membership Inference Attacks (MIA) remains critically underexplored. This paper presents the first system…

Cited by 0SourceScholar
2025

Castle: Causal Cascade Updates in Relational Databases with Large Language Models

EMNLP 2025

This work introduces Castle, the first framework for schema-only cascade update generation using large language models (LLMs). Despite recent advances in LLMs for Text2SQL code generation, existing approaches focus primarily on SELECT queries, neglecting the challenges of SQL update operations and t

Cited by 0SourcePDFScholar
2025

DiTASK: Multi-Task Fine-Tuning with Diffeomorphic Transformations

CVPR 2025poster

Pre-trained Vision Transformers now serve as powerful tools for computer vision. Yet, efficiently adapting them for multiple tasks remains a challenge that arises from the need to modify the rich hidden representations encoded by the learned weight matrices, without inducing interference between tas…

2025

Differentiable Constraint-Based Causal Discovery

NeurIPS 2025poster

Causal discovery from observational data is a fundamental task in artificial intelligence, with far-reaching implications for decision-making, predictions, and interventions. Despite significant advances, existing methods can be broadly categorized as constraint-based or score-based approaches. Cons…

Cited by 0SourcecodeScholar
2025

Holographic Node Representations: Pre-training Task-Agnostic Node Embeddings

ICLR 2025poster

Large general purpose pre-trained models have revolutionized computer vision and natural language understanding. However, the development of general purpose pre-trained Graph Neural Networks (GNNs) lags behind other domains due to the lack of suitable generalist node representations. Existing GNN ar…

Cited by 1SourcePDFScholar
2025

Scalable Out-of-Distribution Robustness in the Presence of Unobserved Confounders

AISTATS 2025poster

We consider the task of out-of-distribution (OOD) generalization, where the distribution shift is due to an unobserved confounder ($Z$) affecting both the covariates ($X$) and the labels ($Y$). This confounding introduces heterogeneity in the predictor, i.e., $P(Y \mid X) = E_{P(Z \mid X)}[P(Y \mid…

Cited by 0SourceScholar
2025

Zero-Shot Generalization of GNNs over Distinct Attribute Domains

ICML 2025poster

Traditional Graph Neural Networks (GNNs) cannot generalize to new graphs with node attributes different from the training ones, making zero-shot generalization across different node attribute domains an open challenge in graph machine learning. In this paper, we propose STAGE, which encodes *statis…

Cited by 6SourcePDFScholar
2024

A Foundation Model for Zero-shot Logical Query Reasoning

NeurIPS 2024poster

Complex logical query answering (CLQA) in knowledge graphs (KGs) goes beyond simple KG completion and aims at answering compositional queries comprised of multiple projections and logical operations. Existing CLQA methods that learn parameters bound to certain entity or relation vocabularies can onl…

2024

DiGRAF: Diffeomorphic Graph-Adaptive Activation Function

NeurIPS 2024poster

In this paper, we propose a novel activation function tailored specifically for graph data in Graph Neural Networks (GNNs). Motivated by the need for graph-adaptive and flexible activation functions, we introduce DiGRAF, leveraging Continuous Piecewise-Affine Based (CPAB) transformations, which we a…

2024

Efficient Subgraph GNNs by Learning Effective Selection Policies

ICLR 2024poster

Subgraph GNNs are provably expressive neural architectures that learn graph representations from sets of subgraphs. Unfortunately, their applicability is hampered by the computational complexity associated with performing message passing on many subgraphs. In this paper, we consider the problem of l…

2024

GraphMETRO: Mitigating Complex Graph Distribution Shifts via Mixture of Aligned Experts

NeurIPS 2024poster

Graph data are inherently complex and heterogeneous, leading to a high natural diversity of distributional shifts. However, it remains unclear how to build machine learning architectures that generalize to the complex distributional shifts naturally occurring in the real world. Here, we develop Grap…

2024

MetaPhysiCa: Improving OOD Robustness in Physics-informed Machine Learning

ICLR 2024spotlight

A fundamental challenge in physics-informed machine learning (PIML) is the design of robust PIML methods for out-of-distribution (OOD) forecasting tasks. These OOD tasks require learning-to-learn from observations of the same (ODE) dynamical system with different unknown ODE parameters, and demand a…

Cited by 3SourcePDFScholar
2024

Vertical Validation: Evaluating Implicit Generative Models for Graphs on Thin Support Regions

UAI 2024poster

There has been a growing excitement that implicit graph generative models could be used to design or discover new molecules for medicine or material design. Because these molecules have not been discovered, they naturally lie in unexplored or scarcely supported regions of the distribution of known m…

Cited by 0SourcePDFScholar
2023

Effective passive membership inference attacks in federated learning against overparameterized models

ICLR 2023poster

This work considers the challenge of performing membership inference attacks in a federated learning setting ---for image classification--- where an adversary can only observe the communication between the central node and a single client (a passive white-box attack). Passive attacks are one of the…

Cited by 21SourcePDFScholar
2022

OOD Link Prediction Generalization Capabilities of Message-Passing GNNs in Larger Test Graphs

NeurIPS 2022accept

This work provides the first theoretical study on the ability of graph Message Passing Neural Networks (gMPNNs) ---such as Graph Neural Networks (GNNs)--- to perform inductive out-of-distribution (OOD) link prediction tasks, where deployment (test) graph sizes are larger than training graphs. We fir…

2021

A Collective Learning Framework to Boost GNN Expressiveness for Node Classification

ICML 2021spotlight

Collective Inference (CI) is a procedure designed to boost weak relational classifiers, specially for node classification tasks. Graph Neural Networks (GNNs) are strong classifiers that have been used with great success. Unfortunately, most existing practical GNNs are not most-expressive (universal)…

Cited by 25SourcePDFScholar
2021

Neural Networks for Learning Counterfactual G-Invariances from Single Environments

ICLR 2021poster

Despite —or maybe because of— their astonishing capacity to fit data, neural networks are believed to have difficulties extrapolating beyond training data distribution. This work shows that, for extrapolations based on finite transformation groups, a model’s inability to extrapolate is unrelated to…

2021

Size-Invariant Graph Representations for Graph Classification Extrapolations

ICML 2021oral

In general, graph representation learning methods assume that the train and test data come from the same distribution. In this work we consider an underexplored area of an otherwise rapidly developing field of graph representation learning: The task of out-of-distribution (OOD) graph classification,…

2020

On the Equivalence between Positional Node Embeddings and Structural Graph Representations

ICLR 2020poster

This work provides the first unifying theoretical framework for node (positional) embeddings and structural graph representations, bridging methods like matrix factorization and graph neural networks. Using invariant theory, we show that relationship between structural representations and node embed…

Cited by 162SourceScholar
2019

Janossy Pooling: Learning Deep Permutation-Invariant Functions for Variable-Size Inputs

ICLR 2019poster

We consider a simple and overarching representation for permutation-invariant functions of sequences (or set functions). Our approach, which we call Janossy pooling, expresses a permutation-invariant function as the average of a permutation-sensitive function applied to all reorderings of the input…

Cited by 238SourcePDFScholar
2019

Relational Pooling for Graph Representations

ICML 2019oral

This work generalizes graph neural networks (GNNs) beyond those based on the Weisfeiler-Lehman (WL) algorithm, graph Laplacians, and diffusions. Our approach, denoted Relational Pooling (RP), draws from the theory of finite partial exchangeability to provide a framework with maximal representation p…