Search Results for author: Salem Said

Found 11 papers, 0 papers with code

Invariant kernels on Riemannian symmetric spaces: a harmonic-analytic approach

no code implementations30 Oct 2023 Nathael Da Costa, Cyrus Mostajeran, Juan-Pablo Ortega, Salem Said

This work aims to prove that the classical Gaussian kernel, when defined on a non-Euclidean symmetric space, is never positive-definite for any choice of parameter.

Geometric Learning with Positively Decomposable Kernels

no code implementations20 Oct 2023 Nathael Da Costa, Cyrus Mostajeran, Juan-Pablo Ortega, Salem Said

Classical kernel methods are based on positive-definite kernels, which map data spaces into reproducing kernel Hilbert spaces (RKHS).

Geometric Learning of Hidden Markov Models via a Method of Moments Algorithm

no code implementations2 Jul 2022 Berlin Chen, Cyrus Mostajeran, Salem Said

We present a novel algorithm for learning the parameters of hidden Markov models (HMMs) in a geometric setting where the observations take values in Riemannian manifolds.

Riemannian statistics meets random matrix theory: towards learning from high-dimensional covariance matrices

no code implementations1 Mar 2022 Salem Said, Simon Heuveline, Cyrus Mostajeran

Its main contribution is to prove that Riemannian Gaussian distributions of real, complex, or quaternion covariance matrices are equivalent to orthogonal, unitary, or symplectic log-normal matrix ensembles.

On Riemannian Stochastic Approximation Schemes with Fixed Step-Size

no code implementations15 Feb 2021 Alain Durmus, Pablo Jiménez, Éric Moulines, Salem Said

This result gives rise to a family of stationary distributions indexed by the step-size, which is further shown to converge to a Dirac measure, concentrated at the solution of the problem at hand, as the step-size goes to 0.

Online learning of Riemannian hidden Markov models in homogeneous Hadamard spaces

no code implementations15 Feb 2021 Quinten Tupker, Salem Said, Cyrus Mostajeran

Hidden Markov models with observations in a Euclidean space play an important role in signal and image processing.

Statistical models and probabilistic methods on Riemannian manifolds

no code implementations26 Jan 2021 Salem Said

This entry contains the core material of my habilitation thesis, soon to be officially submitted.

Statistics Theory Statistics Theory

Hidden Markov chains and fields with observations in Riemannian manifolds

no code implementations11 Jan 2021 Salem Said, Nicolas Le Bihan, Jonathan H. Manton

Hidden Markov chain, or Markov field, models, with observations in a Euclidean space, play a major role across signal and image processing.

Statistics Theory Statistics Theory

Riemannian information gradient methods for the parameter estimation of ECD: Some applications in image processing

no code implementations5 Nov 2020 Jialun Zhou, Salem Said, Yannick Berthoumieu

To develop the ISG method, the Riemannian information gradient is derived taking into account the product manifold associated to the underlying parameter space of the ECD.

Colorization Texture Classification

Convergence Analysis of Riemannian Stochastic Approximation Schemes

no code implementations27 May 2020 Alain Durmus, Pablo Jiménez, Éric Moulines, Salem Said, Hoi-To Wai

This paper analyzes the convergence for a large class of Riemannian stochastic approximation (SA) schemes, which aim at tackling stochastic optimization problems.

Stochastic Optimization

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