Hermanni Hälvä

I am a machine learning PhD student at the University of Helsinki, supervised by Aapo Hyvärinen. My thesis focuses on nonlinear ICA and identifiable representation learning. Before the PhD, I completed a masters degree in computational statistics and machine learning at UCL.

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Research

My main areas of interest are deep generative models and representation learning. I am especially interested in disentanglement learning via nonlinear ICA and the identifiability of these type of models. I am also broadly interested in probabilistic methods, approximate inference and computer vision.

Identifiable Feature Learning for Spatial Data with Nonlinear ICA


Hermanni Hälvä, Jonathan So, Richard E. Turner, Aapo Hyvärinen
27th International Conference on Artificial Intelligence and Statistics (AISTATS), 2024
arxiv / bibtex /

A new algorithm that allows nonlinear ICA to be applied to data with arbitrary high-dimensional latent structures. This model relies on t-process latent space, and was developed with spatio-temporal data in mind.

Disentangling Identifiable Features from Noisy Data with Structured Nonlinear ICA


Hermanni Hälvä, Sylvain Le Corff, Luc Lehéricy, Jonathan So, Yongjie Zhu, Elisabeth Gassiat, Aapo Hyvärinen
35th Conference on Neural Information Processing Systems (NeurIPS), 2021
arxiv / code / poster / slides / openreview / bibtex /

General framework for identifiable disentanglement on structured data with nonlinear ICA. Identifiability holds even in the presence of uknown and arbitrary output noise.

Independent Innovation Analysis for Nonlinear Vector Autoregressive Process


Hiroshi Morioka, Hermanni Hälvä, Aapo Hyvärinen
24th International Conference on Artificial Intelligence and Statistics (AISTATS), 2021
proceedings / arxiv / bibtex /

Nonlinear vector autoregressive process where the innovations at each time point are assumed indepndent and are proven to be identifiable. Can be interpreted as nonlinear ICA for autoregressive time-series.

Hidden Markov Nonlinear ICA: Unsupervised Learning from Nonstationary Time Series


Hermanni Hälvä, Aapo Hyvärinen
Proceedings of the 36th Conference on Uncertainty in Artificial Intelligence (UAI), PMLR volume 124, 2020, 2020
proceedings / arxiv / code / slides / bibtex /

We show that temporal nonstationary as represented by hidden markov chain identifies nonlinear ICA.





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