Archive for CIRM

more of Sugiton at dawn [jatp]

Posted in Mountains, pictures, Running, Travel with tags , , , , , , , , , , , , on November 7, 2021 by xi'an

control variates [seminar]

Posted in pictures, Statistics, Travel, University life with tags , , , , , , , , , , , , , , on November 5, 2021 by xi'an

Today, Petros Dellaportas (whom I have know since the early days of MCMC, when we met in CIRM) gave a seminar at the Warwick algorithm seminar on control variates for MCMC, reminding me of his 2012 JRSS paper. Based on the Poisson equation and using a second control variate to stabilise the Monte Carlo approximation do the first control variate. The difference with usual control variates is finding a first approximate G(x)-q(y|x)G(Y) to F-πF. And the first Poisson equation is using α(x,y)q(y|x) rather than π. Then the second expands log α(x,y)q(y|x) to achieve a manageable term.

Abstract: We provide a general methodology to construct control variates for any discrete time random walk Metropolis and Metropolis-adjusted Langevin algorithm Markov chains that can achieve, in a post-processing manner and with a negligible additional computational cost, impressive variance reduction when compared to the standard MCMC ergodic averages. Our proposed estimators are based on an approximate solution of the Poisson equation for a multivariate Gaussian target densities of any dimension.

I wonder if there were a neural network version that would first build G from scratch and later optimise it towards solving the Poisson equation. As in this recent arXival I haven’t read (yet).

Sugiton at dawn [jatp]

Posted in Mountains, pictures, Running, Travel with tags , , , , , , , , , , on October 28, 2021 by xi'an

off to Luminy!!!

Posted in Mountains, pictures, Running, Statistics, Travel, University life with tags , , , , , , , , , , , , on October 24, 2021 by xi'an

Loup y es-tu?

Posted in Statistics with tags , , , , , , , , , , , , on September 20, 2021 by xi'an

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