Publications related to Finite geometry

Friction and fracture: richness and complexity in dynamic rupture

Understanding how things break and slide is of paramount importance to describe the dynamics of a broad range of physical systems. This includes day-to-day problems such as the breaking of a glass of wine or the sliding of skis on snow, but also engineerin ...

EPFL2023

Convex optimization in sums of Banach spaces

Michaël Unser, Shayan Aziznejad

We characterize the solution of a broad class of convex optimization problems that address the reconstruction of a function from a finite number of linear measurements. The underlying hypothesis is that the solution is decomposable as a finite sum of compo ...

2021

Semi-discrete optimal transport: a solution procedure for the unsquared Euclidean distance case

Valentin Hartmann

We consider the problem of finding an optimal transport plan between an absolutely continuous measure and a finitely supported measure of the same total mass when the transport cost is the unsquared Euclidean distance. We may think of this problem as close ...

SPRINGER HEIDELBERG2020

Incidences Between Planes Over Finite Fields

Van Thang Pham

In this note, we use methods from spectral graph theory to obtain bounds on the number of incidences between k-planes and h-planes in F-q(d), which generalizes a recent result given by Bennett, Iosevich, and Pakianathan (2014). More precisely, we prove tha ...

AMER MATHEMATICAL SOC2019

Load-Transfer Approach for Modeling the Cyclic Thermo-Mechanical Behaviour of Energy Piles

Lyesse Laloui, Melis Sütman

Energy piles are subjected to short- and long-term cyclic thermal loads due to their unique role as heat exchangers. Their response to monotonic temperature change has been investigated by various researchers from both experimental and numerical points of ...

2018

Structure of certain Weyl modules for the Spin groups

Mikaël Cavallin

Let K be an algebraically closed field of characteristic and let W be a finite-dimensional K-vector space of dimension greater than or equal to 5. In this paper, we give the structure of certain Weyl modules for in the case where , as well as the dimension ...

2018

Erdos Distinct Distances Problem and Extensions over Finite Spaces

Van Thang Pham

In this thesis we study a number of problems in Discrete Combinatorial Geometry in finite spaces. The contents in this thesis are structured as follows: In Chapter 1 we will state the main results and the notations which will be used throughout the thesis. ...

EPFL2017

Extension complexity of stable set polytopes of bipartite graphs

Yuri Faenza, Manuel Francesco Aprile

The extension complexity xc(P) of a polytope P is the minimum number of facets of a polytope that affinely projects to P. Let G be a bipartite graph with n vertices, m edges, and no isolated vertices. Let STAB(G) be the convex hull of the stable sets of G. ...

Springer2017

Spin excitations and quantum criticality in the quasi-one-dimensional Ising-like ferromagnet CoCl2⋅2D2O in a transverse field

Henrik Moodysson Rønnow, Ursula Bengaard Hansen

We present experimental evidence for a quantum phase transition in the easy-axis S=3/2 anisotropic quasi-one-dimensional ferromagnet CoCl2⋅2D2O in a transverse field. Elastic neutron scattering shows that the magnetic order parameter vanishes at a transver ...

2017

Patching And Weak Approximation In Isometry Groups

Eva Bayer Fluckiger

Let R be a semilocal principal ideal domain. Two algebraic objects over R in which scalar extension makes sense (e.g. quadratic spaces) are said to be of the same genus if they become isomorphic after extending scalars to all completions of R and its fract ...

Amer Mathematical Soc2017

A Szemeredi-Trotter type theorem, sum-product estimates in finite quasifields, and related results

Van Thang Pham

We prove a Szemeredi-Trotter type theorem and a sum product estimate in the setting of finite quasifields. These estimates generalize results of the fourth author, of Garaev, and of Vu. We generalize results of Gyarmati and Sarkozy on the solvability of th ...

Academic Press Inc Elsevier Science2017

On The Number Of Ordinary Conics

Frank de Zeeuw, Adrian Claudiu Valculescu

We prove a lower bound on the number of ordinary conics determined by a finite point set in R-2. An ordinary conic for S subset of R-2 is a conic that is determined by five points of S and contains no other points of S. Wiseman and Wilson proved the Sylves ...

SIAM Publications2016

Constrained LQR Using Online Decomposition Techniques

Georgios Stathopoulos, Colin Neil Jones

This paper presents an algorithm to solve the infinite horizon constrained linear quadratic regulator (CLQR) problem using operator splitting methods. First, the CLQR problem is reformulated as a (finite-time) model predictive control (MPC) problem without ...

2016

Representer Theorems for Sparsity-Promoting $ ℓ _{ 1 } $ Regularization

Michaël Unser, Julien René Pierre Fageot, Harshit Gupta

We present a theoretical analysis and comparison of the effect of

ℓ _{ 1 }

versus

ℓ _{ 2 }

regularization for the resolution of ill-posed linear inverse and/or compressed sensing problems. Our formulation covers the most general setting where the s ...

IEEE2016

A concurrent atomistic and continuum coupling method with applications to thermo-mechanical problems

Jean-François Molinari, Guillaume Anciaux, Srinivasa Babu Ramisetti

We present a novel method to couple molecular dynamics with finite elements at finite temperatures using spatial filters. The mismatch in the dispersion relations between continuum and atomistic models leads, at finite temperature, to unwanted mesh vibrati ...

Wiley-Blackwell2014

Sesquilinear forms over rings with involution

Eva Bayer Fluckiger, Daniel Arnold Moldovan

Many classical results concerning quadratic forms have been extended to Hermitian forms over algebras with involution. However, not much is known in the case of sesquilinear forms without any symmetry property. The present paper will establish a Witt cance ...

Elsevier2014

Diameter Graphs in R-4

Andrei Kupavskii

A diameter graph in is a graph whose set of vertices is a finite subset of and whose set of edges is formed by pairs of vertices that are at diameter apart. This paper is devoted to the study of different extremal properties of diameter graphs in and on a ...

Springer2014

Multilevel Monte Carlo methods for stochastic elliptic multiscale PDEs

Assyr Abdulle

In this paper Monte Carlo finite element approximations for elliptic homogenization problems with random coefficients, which oscillate on n is an element of N a priori known, separated microscopic length scales, are considered. The convergence of multileve ...

2013

Acoustic Echoes Reveal Room Shape

Martin Vetterli, Yue Lu, Ivan Dokmanic, Reza Parhizkar, Andreas Walther

Imagine that you are blindfolded inside an unknown room. You snap your fingers and listen to the room’s response. Can you hear the shape of the room? Some people can do it naturally, but can we design computer algorithms that hear rooms? We show how to com ...

National Academy of Sciences2013

Nondispersive solutions to the $L^2$-critical half-wave equation

Joachim Krieger

We consider the focusing

L^2

-critical half-wave equation in one space dimension

i \partial_t u = D u - |u|^2 u,

where

D

denotes the first-order fractional derivative. Standard arguments show that there is a critical threshold

M_* > 0

such that all ...

Springer Verlag2013