39,409 research outputs found
A path-integral approach to Bayesian inference for inverse problems using the semiclassical approximation
We demonstrate how path integrals often used in problems of theoretical
physics can be adapted to provide a machinery for performing Bayesian inference
in function spaces. Such inference comes about naturally in the study of
inverse problems of recovering continuous (infinite dimensional) coefficient
functions from ordinary or partial differential equations (ODE, PDE), a problem
which is typically ill-posed. Regularization of these problems using
function spaces (Tikhonov regularization) is equivalent to Bayesian
probabilistic inference, using a Gaussian prior. The Bayesian interpretation of
inverse problem regularization is useful since it allows one to quantify and
characterize error and degree of precision in the solution of inverse problems,
as well as examine assumptions made in solving the problem -- namely whether
the subjective choice of regularization is compatible with prior knowledge.
Using path-integral formalism, Bayesian inference can be explored through
various perturbative techniques, such as the semiclassical approximation, which
we use in this manuscript. Perturbative path-integral approaches, while
offering alternatives to computational approaches like Markov-Chain-Monte-Carlo
(MCMC), also provide natural starting points for MCMC methods that can be used
to refine approximations.
In this manuscript, we illustrate a path-integral formulation for inverse
problems and demonstrate it on an inverse problem in membrane biophysics as
well as inverse problems in potential theories involving the Poisson equation.Comment: Fixed some spelling errors and the author affiliations. This is the
version accepted for publication by J Stat Phy
Parametric and non-parametric gradient matching for network inference:a comparison
Abstract Background Reverse engineering of gene regulatory networks from time series gene-expression data is a challenging problem, not only because of the vast sets of candidate interactions but also due to the stochastic nature of gene expression. We limit our analysis to nonlinear differential equation based inference methods. In order to avoid the computational cost of large-scale simulations, a two-step Gaussian process interpolation based gradient matching approach has been proposed to solve differential equations approximately. Results We apply a gradient matching inference approach to a large number of candidate models, including parametric differential equations or their corresponding non-parametric representations, we evaluate the network inference performance under various settings for different inference objectives. We use model averaging, based on the Bayesian Information Criterion (BIC), to combine the different inferences. The performance of different inference approaches is evaluated using area under the precision-recall curves. Conclusions We found that parametric methods can provide comparable, and often improved inference compared to non-parametric methods; the latter, however, require no kinetic information and are computationally more efficient
Bayesian Neural Controlled Differential Equations for Treatment Effect Estimation
Treatment effect estimation in continuous time is crucial for personalized
medicine. However, existing methods for this task are limited to point
estimates of the potential outcomes, whereas uncertainty estimates have been
ignored. Needless to say, uncertainty quantification is crucial for reliable
decision-making in medical applications. To fill this gap, we propose a novel
Bayesian neural controlled differential equation (BNCDE) for treatment effect
estimation in continuous time. In our BNCDE, the time dimension is modeled
through a coupled system of neural controlled differential equations and neural
stochastic differential equations, where the neural stochastic differential
equations allow for tractable variational Bayesian inference. Thereby, for an
assigned sequence of treatments, our BNCDE provides meaningful posterior
predictive distributions of the potential outcomes. To the best of our
knowledge, ours is the first tailored neural method to provide uncertainty
estimates of treatment effects in continuous time. As such, our method is of
direct practical value for promoting reliable decision-making in medicine
A Probabilistic State Space Model for Joint Inference from Differential Equations and Data
Mechanistic models with differential equations are a key component of
scientific applications of machine learning. Inference in such models is
usually computationally demanding, because it involves repeatedly solving the
differential equation. The main problem here is that the numerical solver is
hard to combine with standard inference techniques. Recent work in
probabilistic numerics has developed a new class of solvers for ordinary
differential equations (ODEs) that phrase the solution process directly in
terms of Bayesian filtering. We here show that this allows such methods to be
combined very directly, with conceptual and numerical ease, with latent force
models in the ODE itself. It then becomes possible to perform approximate
Bayesian inference on the latent force as well as the ODE solution in a single,
linear complexity pass of an extended Kalman filter / smoother - that is, at
the cost of computing a single ODE solution. We demonstrate the expressiveness
and performance of the algorithm by training, among others, a non-parametric
SIRD model on data from the COVID-19 outbreak.Comment: 12 pages (+ 5 pages appendix), 7 figures. In: Advances in Neural
Information Processing Systems (NeurIPS 2021
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