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Stefanos Eleftheriadis

6 accepted papers

2020

Doubly Sparse Variational Gaussian Processes

AISTATS 2020poster

The use of Gaussian process models is typically limited to datasets with a few tens of thousands of observations due to their complexity and memory footprint.The two most commonly used methods to overcome this limitation are 1) the variational sparse approximation which relies on inducing points and…

2019

Banded Matrix Operators for Gaussian Markov Models in the Automatic Differentiation Era

AISTATS 2019poster

Banded matrices can be used as precision matrices in several models including linear state-space models, some Gaussian processes, and Gaussian Markov random fields. The aim of the paper is to make modern inference methods (such as variational inference or gradient-based sampling) available for Gauss…

Cited by 40SourcePDFScholar
2018

Natural Gradients in Practice: Non-Conjugate Variational Inference in Gaussian Process Models

AISTATS 2018poster

The natural gradient method has been used effectively in conjugate Gaussian process models, but the non-conjugate case has been largely unexplored. We examine how natural gradients can be used in non-conjugate stochastic settings, together with hyperparameter learning. We conclude that the natural g…

Cited by 0SourcePDFScholar
2017

DeepCoder: Semi-Parametric Variational Autoencoders for Automatic Facial Action Coding

ICCV 2017poster

Human face exhibits an inherent hierarchy in its representations (i.e., holistic facial expressions can be encoded via a set of facial action units (AUs) and their intensity). Variational (deep) auto-encoders (VAE) have shown great results in unsupervised extraction of hierarchical latent representa…

Cited by 56PDFScholar
2017

Identification of Gaussian Process State Space Models

NeurIPS 2017poster

The Gaussian process state space model (GPSSM) is a non-linear dynamical system, where unknown transition and/or measurement mappings are described by GPs. Most research in GPSSMs has focussed on the state estimation problem, i.e., computing a posterior of the latent state given the model. However,…

Cited by 148SourcePDFScholar
2015

Multi-Conditional Latent Variable Model for Joint Facial Action Unit Detection

ICCV 2015poster

We propose a novel multi-conditional latent variable model for simultaneous facial feature fusion and detection of facial action units. In our approach we exploit the structure-discovery capabilities of generative models such as Gaussian processes, and the discriminative power of classifiers such as…

Cited by 115PDFScholar