Bartholdi, Laurent Woess, Wolfgang
Published in
Journal of Fourier Analysis and Applications

The Diestel-Leader graph DL(q, r) is the horocyclic product of the homogeneous trees with respective degrees q + 1 and r + 1. When q = r, it is the Cayley graph of the lamplighter group (wreath product) ℤq ≀ ℤ with respect to a natural generating set. For the “Simple random walk” (SRW) operator on the latter group, Grigorchuk and Zuk, and Dicks and...

Bayer-Fluckiger, Eva Suarez, Ivan
Published in
Archiv der Mathematik

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Becher, Karim Johannes
Published in
Archiv der Mathematik

This note is motivated by the problem of determining the u-invariant of a field F of characteristic different from two when it is known that \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69p...

Houriet, Julien
Published in
Archiv der Mathematik

By a result of H.W. Lenstra, one can prove that a number field is Euclidean with the aid of exceptional units. We describe two methods computing exceptional sequences, i.e., sets of units such that the difference of any two of them is still a unit. The second method is based on a graph theory algorithm for the maximum clique problem. This yielded 4...

Bartholdi, Laurent de Cornulier, Yves
Published in
Archiv der Mathematik

We exhibit infinite, solvable, virtually abelian groups with a fixed number of generators, having arbitrarily large balls consisting of torsion elements. We also provide a sequence of 3-generator non-virtually nilpotent polycyclic groups of algebraic entropy tending to zero. All these examples are obtained by taking appropriate quotients of finitel...

Wiesemeier, Theresa Hay, Mark Pohnert, Georg
Published in
Aquatic Sciences

The chemical defence potential against herbivores of certain Dictyotalean brown algae increases after tissue disruption. This wound activated defence has been explored in bioassays, but the metabolic pathways behind it are unknown. Here we describe a metabolic profiling approach to identify the activated defence metabolites. Before and after tissue...

Baylis, W. E. Cabrera, R. Keselica, J. D.
Published in
Advances in Applied Clifford Algebras

Although intrinsic spin is usually viewed as a purely quantum property with no classical analog, we present evidence that fermion spin has a classical origin rooted in the geometry of three-dimensional physical space. Our approach to the quantum/classical interface is based on a formulation of relativistic classical mechanics that uses spinors. Spi...

Reem, Daniel Reich, Simeon Zaslavski, Alexander J.
Published in
Journal of Fixed Point Theory and Applications

We establish two fixed point theorems for certain mappings of contractive type. The first result is concerned with the case where such mappings take a nonempty, closed subset of a complete metric space X into X, and the second with an application of the continuation method to the case where they satisfy the Leray–Schauder boundary condition in Bana...

Lecampion, Brice Jeffrey, Rob Detournay, Emmanuel
Published in
pure and applied geophysics

This paper discusses the resolution of geometrical characteristics of pressurized fractures from tiltmeter data. The quasi-static deformation and tilt field induced by such fractures can be modeled by superposition of displacement discontinuity (DD) singularities. Despite the relatively common use of such measurements to infer fracture characterist...

Maerten, Daniel
Published in
Annales Henri Poincaré

The aim of this paper is to prove a positive energy-momentum theorem under the (well known in general relativity) dominant energy condition, for AdS-asymptotically hyperbolic manifolds. These manifolds are by definition endowed with a Riemannian metric and a symmetric 2-tensor which respectively tend to the metric and second fundamental form of a s...