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Eliezer De Souza Da Silva

2024


On Divergence Measures for Training GFlowNets

Novel approach to training Generative Flow Networks (GFlowNets) by minimizing divergence measures such as Renyi-$\alpha$, Tsallis-$\alpha$, and Kullback-Leibler (KL) divergences. Stochastic gradient estimators using variance reduction techniques leads to faster and stabler training.

Analyzing GFlowNets: Stability, Expressiveness, and Assessment

How balance violations impact the learned distribution, motivating an weighted balance loss to improve training. For graph distributions, there are scenarios where balance is unattainable, and richer embeddings of children’s states is needed enhance expressiveness. To measure of distributional correctness in GFN we introduce a provable correct novel assessment metric.

2023


Prior Specification for Bayesian Matrix Factorization via Prior Predictive Matching

A method for prior specification by optimizing hyperparameters via the prior predictive distribution. This approach matches virtual statistics generated by the prior to certain target values. We apply it to Bayesian matrix factorization models, obtaining a close-formula for the rank of the latent variables, and analytically determine the matching hyperparameters, and extend it to general models through stochastic optimization.

Human-in-the-Loop Causal Discovery under Latent Confounding using Ancestral GFlowNets

We introduce a causal discovery method that estimates uncertainty and refines results with expert feedback. Using generative flow networks, we sample belief-based ancestral graphs that captures latent-confounding, and iteratively reduce uncertainty through human input, with a human-in-the-loop approach.

2019


Time is of the Essence: a Joint Hierarchical RNN and Point Process Model for Time and Item Predictions

A joint model combining a Hierarchical RNN for session-based recommendations and a Point Process model for predicting return times. This approach improves both recommendation accuracy and return-time predictions over strong baselines.

2017


Content-Based Social Recommendation with Poisson Matrix Factorization

A latent variable probabilistic model for recommender systems that combines social trust, item content, and user preferences into a unified Poisson matrix factorization framework. This model jointly factorizes the user–item interaction matrix and item–content matrix, accounting for social relationships and content information to enhance recommendation accuracy.

2014