arXiv subjects

Martin Mayer

Publications and source records attributed to Martin Mayer.

23 records · Page 2Linked to original sources

arXiv2015

A scalar curvature flow in low dimensions

Let $(M^{n},g_{0})$ be a $n=3,4,5$ dimensional, closed Riemannian manifold of positive Yamabe invariant. For a smooth function $K>0$ on $M$ we consider a scalar curvature flow, that tends to prescribe $K$ as the scalar curvature of a metric $g$ conformal to $g_{0}$. We show global existence and in case $M$ is not conformally equivalent to the standard sphere smooth flow convergence and solubility of the prescribed scalar curvature problem under suitable conditions on $K$.

math.DG↗

arXiv2015

The inverse Willmore flow

Instead of investigating the Willmore flow for two-dimensional, closed immersed surfaces directly we turn to its inversion. We give a lower bound on the lifespan of this inverse Willmore flow, depending on the concentration of curvature in space and the extension of the initial surface, as well as a characterization of its breakdown, which might occur in finite time.

math.DG↗

arXiv2015

Bayesian Optimal Approximate Message Passing to Recover Structured Sparse Signals

We present a novel compressed sensing recovery algorithm - termed Bayesian Optimal Structured Signal Approximate Message Passing (BOSSAMP) - that jointly exploits the prior distribution and the structured sparsity of a signal that shall be recovered from noisy linear measurements. Structured sparsity is inherent to group sparse and jointly sparse signals. Our algorithm is based on approximate message passing that poses a low complexity recovery algorithm whose Bayesian optimal version allows to specify a prior distribution for each signal component. We utilize this feature in order to establish an iteration-wise extrinsic group update step, in which likelihood ratios of neighboring group elements provide soft information about a specific group element. Doing so, the recovery of structured signals is drastically improved. We derive the extrinsic group update step for a sparse binary and a sparse Gaussian signal prior, where the nonzero entries are either one or Gaussian distributed, respectively. We also explain how BOSSAMP is applicable to arbitrary sparse signals. Simulations demonstrate that our approach exhibits superior performance compared to the current state of the art, while it retains a simple iterative implementation with low computational complexity.

cs.IT↗

arXiv2015

Proof of the remaining cases of the Yamabe boundary problem

In this paper, we solve the remaining cases of the boundary Yamabe problem introduced by Escobar in 1992. Indeed, using the bubbles of Brendle-Chen, which are an adaptation to manifolds with boundary of the original ones introduced by Brendle for the study of the Yamabe flow on closed Riemannian manifolds of dimension greater or equal to 6, and the algebraic topological argument of Bahri-Coron, we solve the cases left open after the work of Brendle-Chen. Thus combining our work with the ones of Brendle-Chen and Escobar, we have that the boundary Yamabe problem is a done deal.

math.DG↗

arXiv2015

Barycenter technique and the Riemann mapping problem of Escobar

We solve the remaining cases of the Riemann mapping problem of Escobar. Indeed, performing a suitable scheme of the barycenter technique of Bahri-Coron via the Chen's bubbles, we solve the cases left open after the work of Chen. Thus, combining our work with the ones of Almaraz, Chen, Escobar and Marques we have that every compact Riemannian manifold with boundary of dimension greater or equal than 3 carries a conformal scalar flat metric with constant mean curvature.

math.DG↗