75 citations · 236 across the 75 of their papers we have counts for
83 papers
Operator Calculus for Population-Based Optimization: Modular Convergence and Finite-Population Guarantees
Pekka Malo, Lauri Viitasaari, Patrik Nummi +3
Population-based optimizers combine update rules such as mutation, selection, and recombination. When one rule changes, it is often unclear which convergence guarantees survive or…
Parameter estimation in generalized fractional neuronal models
Pauliina Ilmonen, Milla Laurikkala, Enrica Pirozzi +2
We investigate a generalized stochastic fractional neuronal model combining fractional dynamics with correlated stochastic inputs. The proposed framework is described by a fraction…
Lower path regularity in all dimensions
Michael Hinz, Jonas M. Tölle, Lauri Viitasaari
We prove precise almost sure lower path regularity results for a wide class of stochastic processes in all space dimensions . Examples include Gaussian processes, in parti…
Error analysis for learning fractional stochastic differential equations with applications in neural approximations
Mahdi Dehshiri, Kerlyns Martinez, Lauri Viitasaari
This paper develops a framework for the error analysis in nonparametric model fitting of fractional stochastic differential equations based on discrete observations. We identify an…
Smoothness of martingale observables and generalized Feynman-Kac formulas
Alex Karrila, Lauri Viitasaari
We prove that, under the Hörmander criterion on an Itô process, all its martingale observables are smooth. As a consequence, we also obtain a generalized Feynman-Kac formula provid…
On fractal minimizers and potentials of occupation measures
Michael Hinz, Jonas M. Tölle, Lauri Viitasaari
We consider four prototypes of variational problems and prove the existence of fractal minimizers through the direct method in the calculus of variations. By design these minimizer…
Extended Kalman Filtering on Stiefel Manifolds
Jordi-Lluís Figueras, Aron Persson, Lauri Viitasaari
A generalisation of the extended Kalman filter for Stiefel manifold-valued measurements is presented. We provide simulations on the 2-sphere and the space of orthogonal 4-by-2 matr…
On the Convergence of the Extended Kalman Filter on Stiefel Manifolds when Observing a Constant Particle with Measurement Errors
Jordi-Lluís Figueras, Aron Persson, Lauri Viitasaari
In this paper we first introduce the setting of filtering on Stiefel manifolds. Then, assuming the underlying system process is constant, the convergence of the extended Kalman fil…
Characterization of continuous stationary fields as generalized Ornstein-Uhlenbeck fields via multi-parameter Langevin equation and multiple Riemann-Stieltjes integration
Marko Voutilainen, Pauliina Ilmonen, Lauri Viitasaari
In this article, we characterize continuous stationary fields via generalized Langevin dynamics. This gives natural connections between stationary fields, stationary increment fiel…
Non-parametric estimation of non-linear diffusion coefficient in parabolic SPDEs
Martin Andersson, Benny Avelin, Valentin Garino +2
In this article, we introduce a novel non-parametric predictor, based on conditional expectation, for the unknown diffusion coefficient function in the stochastic partial diffe…
Data driven modeling of multiple interest rates with generalized Vasicek-type models
Pauliina Ilmonen, Milla Laurikkala, Kostiantyn Ralchenko +2
The Vasicek model is a commonly used interest rate model, and there exist many extensions and generalizations of it. However, most generalizations of the model are either univariat…
Tanaka formula for SDEs driven by fractional Brownian motion
Tommi Sottinen, Ercan Sönmez, Lauri Viitasaari
We derive a Tanaka-type formula for the solution of a stochastic differential equation (SDE) driven by fractional Brownian motion (fBm) with Hurst parameter . Whil…
Moment Estimator-Based Extreme Quantile Estimation with Erroneous Observations: Application to Elliptical Extreme Quantile Region Estimation
Jaakko Pere, Pauliina Ilmonen, Lauri Viitasaari
In many application areas of extreme value theory, the variables of interest are not directly observable but instead contain errors. In this article, we quantify the effect of thes…
Cut-off phenomenon and asymptotic mixing for multivariate general linear processes
Gerardo Barrera, Michael A. Högele, Pauliina Ilmonen +1
The small noise cut-off phenomenon in continuous time and space has been studied in the recent literature for the linear and non-linear stable Langevin dynamics with additive Lévy…
Convex Regularization and Convergence of Policy Gradient Flows under Safety Constraints
Pekka Malo, Lauri Viitasaari, Antti Suominen +2
This paper examines reinforcement learning (RL) in infinite-horizon decision processes with almost-sure safety constraints, crucial for applications like autonomous systems, financ…
On parameter estimation for based on projected data into
Jordi-Lluís Figueras, Aron Persson, Lauri Viitasaari
We consider the projected normal distribution, with isotropic variance, on the 2-sphere using intrinsic statistics. We show that in this case, the expectation commutes with the pro…
Zombie Epidemic -- on Modeling the Effect of Interventions
Kaisa Ek, Aleksi Avela, Willehard Haaki +7
The recent COVID-19 pandemic has highlighted the need of studying extreme, life-threatening phenomena in advance. In this article, a zombie epidemic in Uusimaa region in Finland is…
On explosion time in stochastic differential equations driven by fractional Brownian motion
Johanna Garzon, Jorge A. Leon, Soledad Torres +2
In this article, we study the explosion time of the solution to autonomous stochastic differential equations driven by the fractional Brownian motion with Hurst parameter .…
Variability and the existence of rough integrals with irregular coefficients
Michael Hinz, Jonas M. Tölle, Lauri Viitasaari
Within the context of rough path analysis via fractional calculus, we show how variability can be used to prove the existence of integrals with respect to Hölder continuous multipl…
Renormalized stochastic pressure equation with log-correlated Gaussian coefficients
Benny Avelin, Tuomo Kuusi, Patrik Nummi +3
We study periodic solutions to the following divergence-form stochastic partial differential equation with Wick-renormalized gradient on the -dimensional flat torus $\mathbb{T}^…
1D stochastic pressure equation with log-correlated Gaussian coefficients
Benny Avelin, Tuomo Kuusi, Patrik Nummi +3
We study unique solvability for one dimensional stochastic pressure equation with diffusion coefficient given by the Wick exponential of log-correlated Gaussian fields. We prove we…
Transfer principle for fractional Ornstein-Uhlenbeck processes
Tommi Sottinen, Lauri Viitasaari
We prove the transfer principle for fractional Ornstein-Uhlenbeck processes, i.e., we construct a Brownian motion that has the same filtration as the fractional Ornstein-Uhlenbeck…
On the Impact of Approximation Errors on Extreme Quantile Estimation with Applications to Functional Data Analysis
Jaakko Pere, Benny Avelin, Valentin Garino +2
We study the effect of approximation errors in assessing the extreme behavior of heavy-tailed random objects. We give conditions for the approximation error such that the standard…
Discretisation error for stochastic integrals with respect to the fractional Brownian motion with discontinuous integrands and local times
Valentin Garino, Lauri Viitasaari
We consider equidistant Riemann approximations of stochastic integrals with respect to the fractional Brownian motion with , where is an ar…