Speaker: Jean-Marc Azais (University of Toulouse 3)
Time: 14h00, Thursday, October 4, 2018 Location: Room 302, Building A5, Institute of Mathematics Abstract: This talk introduces exact testing procedures on the mean of a Gaussian process $X$ derived from the outcomes of $ell_1$-minimization over the space of complex valued measures. The process $X$ can thought as the sum of two terms: first, the convolution between some kernel and a target atomic measure (mean of the process); second, a random perturbation by an additive (centered) Gaussian process. The first testing procedure considered is based on a dense sequence of grids on the index set of $X$ and we establish that it converges (as the grid step tends to zero) to a randomized testing procedure: the decision of the test depends on the observation $X$ and also on an independent random variable. The second testing procedure is based on the maxima and the Hessian of $X$ in a grid-less manner. We show that both testing procedures can be performed when the variance is unknown (and the correlation function of $X$ is known). These testing procedures can be used for the problem of deconvolution over the space of complex valued measures, and applications in frame of the Super-Resolution theory are presented. As a byproduct, numerical investigations may demonstrate that our grid-less method is more powerful (it~detects sparse alternatives) than tests based on very thin~grids. |