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  1. No Access

    Article

    Bayesian parameter inference for partially observed stochastic volterra equations

    In this article we consider Bayesian parameter inference for a type of partially observed stochastic Volterra equation (SVE). SVEs are found in many areas such as physics and mathematical finance. In the latte...

    Ajay Jasra, Hamza Ruzayqat, Amin Wu in Statistics and Computing (2024)

  2. Article

    Open Access

    Multi-index Sequential Monte Carlo Ratio Estimators for Bayesian Inverse problems

    We consider the problem of estimating expectations with respect to a target distribution with an unknown normalising constant, and where even the un-normalised target needs to be approximated at finite resolut...

    Ajay Jasra, Kody J. H. Law, Neil Walton in Foundations of Computational Mathematics (2023)

  3. No Access

    Article

    Bayesian parameter inference for partially observed stochastic differential equations driven by fractional Brownian motion

    In this paper we consider Bayesian parameter inference for partially observed fractional Brownian motion models. The approach we follow is to time-discretize the hidden process and then to design Markov chain ...

    Mohamed Maama, Ajay Jasra, Hernando Ombao in Statistics and Computing (2022)

  4. Article

    Open Access

    A 4D-Var method with flow-dependent background covariances for the shallow-water equations

    The 4D-Var method for filtering partially observed nonlinear chaotic dynamical systems consists of finding the maximum a-posteriori (MAP) estimator of the initial condition of the system given observations ove...

    Daniel Paulin, Ajay Jasra, Alexandros Beskos, Dan Crisan in Statistics and Computing (2022)

  5. No Access

    Article

    Multilevel estimation of normalization constants using ensemble Kalman–Bucy filters

    In this article we consider the application of multilevel Monte Carlo, for the estimation of normalizing constants. In particular we will make use of the filtering algorithm, the ensemble Kalman–Bucy filter (E...

    Hamza Ruzayqat, Neil K. Chada, Ajay Jasra in Statistics and Computing (2022)

  6. No Access

    Article

    Unbiased approximation of posteriors via coupled particle Markov chain Monte Carlo

    Markov chain Monte Carlo (MCMC) is a powerful methodology for the approximation of posterior distributions. However, the iterative nature of MCMC does not naturally facilitate its use with modern highly parall...

    Willem van den Boom, Ajay Jasra, Maria De Iorio in Statistics and Computing (2022)

  7. No Access

    Chapter and Conference Paper

    Randomized Multilevel Monte Carlo for Embarrassingly Parallel Inference

    This position paper summarizes a recently developed research program focused on inference in the context of data centric science and engineering applications, and forecasts its trajectory forward over the next...

    Ajay Jasra, Kody J. H. Law in Driving Scientific and Engineering Discove… (2022)

  8. Article

    Open Access

    Uncertainty modelling and computational aspects of data association

    A novel solution to the smoothing problem for multi-object dynamical systems is proposed and evaluated. The systems of interest contain an unknown and varying number of dynamical objects that are partially obs...

    Jeremie Houssineau, Jiajie Zeng, Ajay Jasra in Statistics and Computing (2021)

  9. Article

    Open Access

    Unbiased estimation of the gradient of the log-likelihood in inverse problems

    We consider the problem of estimating a parameter \(\theta \in \Theta \subseteq {\mathbb {R}}^{d_{\theta }}\) ...

    Ajay Jasra, Kody J. H. Law, Deng Lu in Statistics and Computing (2021)

  10. No Access

    Article

    Multilevel particle filters for the non-linear filtering problem in continuous time

    In the following article we consider the numerical approximation of the non-linear filter in continuous-time, where the observations and signal follow diffusion processes. Given access to high-frequency, but d...

    Ajay Jasra, Fangyuan Yu, Jeremy Heng in Statistics and Computing (2020)

  11. Article

    Open Access

    Correction to: Multilevel particle filters for Lévy-driven stochastic differential equations

    The article Multilevel particle filters for Lévy-driven stochastic differential equations, written by Ajay Jasra, Kody J. H. Law, Prince Peprah Osei, was originally published electronically on the publisher’s ...

    Ajay Jasra, Kody J. H. Law, Prince Peprah Osei in Statistics and Computing (2019)

  12. Article

    Open Access

    Multilevel particle filters for Lévy-driven stochastic differential equations

    We develop algorithms for computing expectations with respect to the laws of models associated to stochastic differential equations driven by pure Lévy processes. We consider filtering such processes as well a...

    Ajay Jasra, Kody J. H. Law, Prince Peprah Osei in Statistics and Computing (2019)

  13. Article

    Open Access

    Optimization Based Methods for Partially Observed Chaotic Systems

    In this paper we consider filtering and smoothing of partially observed chaotic dynamical systems that are discretely observed, with an additive Gaussian noise in the observation. These models are found in a w...

    Daniel Paulin, Ajay Jasra, Dan Crisan in Foundations of Computational Mathematics (2019)

  14. No Access

    Article

    A method for high-dimensional smoothing

    We consider the problem of the computation of smoothed additive functional, which are some integrals with respect to the joint smoothing distribution. It is a key issue in inference for general state-space mod...

    Yaxian Xu, Ajay Jasra in Journal of the Korean Statistical Society (2019)

  15. No Access

    Article

    On coupling particle filter trajectories

    Particle filters are a powerful and flexible tool for performing inference on state-space models. They involve a collection of samples evolving over time through a combination of sampling and re-sampling steps...

    Deborshee Sen, Alexandre H Thiery, Ajay Jasra in Statistics and Computing (2018)

  16. No Access

    Article

    Multilevel particle filters: normalizing constant estimation

    In this article, we introduce two new estimates of the normalizing constant (or marginal likelihood) for partially observed diffusion (POD) processes, with discrete observations. One estimate is biased but non...

    Ajay Jasra, Kengo Kamatani, Prince Peprah Osei, Yan Zhou in Statistics and Computing (2018)

  17. No Access

    Article

    Biased Online Parameter Inference for State-Space Models

    We consider Bayesian online static parameter estimation for state-space models. This is a very important problem, but is very computationally challenging as the state-of-the art methods that are exact, often h...

    Pierre Del Moral, Ajay Jasra, Yan Zhou in Methodology and Computing in Applied Probability (2017)

  18. No Access

    Article

    Variational inference for sparse spectrum Gaussian process regression

    We develop a fast variational approximation scheme for Gaussian process (GP) regression, where the spectrum of the covariance function is subjected to a sparse approximation. Our approach enables uncertainty i...

    Linda S. L. Tan, Victor M. H. Ong, David J. Nott, Ajay Jasra in Statistics and Computing (2016)

  19. No Access

    Article

    Monte Carlo algorithms for computing \(\alpha \) -permanents

    We consider the computation of the \(\alpha \) α ...

    Junshan Wang, Ajay Jasra in Statistics and Computing (2016)

  20. No Access

    Article

    Sequential Monte Carlo methods for Bayesian elliptic inverse problems

    In this article, we consider a Bayesian inverse problem associated to elliptic partial differential equations in two and three dimensions. This class of inverse problems is important in applications such as hy...

    Alexandros Beskos, Ajay Jasra, Ege A. Muzaffer in Statistics and Computing (2015)

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