Browsing 2020 by Title
Now showing items 3-22 of 22
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Generating Finite Coxeter Groups with Elements of the Same Order
[OWP-2020-07] (Mathematisches Forschungsinstitut Oberwolfach, 2020-03-16)Supposing $G$ is a group and $k$ a natural number, $d_k(G)$ is defined to be the minimal number of elements of $G$ of order $k$ which generate $G$ (setting $d_k(G) = 0$ if $G$ has no such generating sets). This paper ... -
Homology and $K$-Theory of Torsion-Free Ample Groupoids and Smale Spaces
[OWP-2020-20] (Mathematisches Forschungsinstitut Oberwolfach, 2020-10-09)Given an ample groupoid, we construct a spectral sequence with groupoid homology with integer coefficients on the second sheet, converging to the $K$-groups of the groupoid C*-algebra when the groupoid has torsion-free ... -
Hopf Algebras in Combinatorics, Volume 1
[OWP-2020-14] (Mathematisches Forschungsinstitut Oberwolfach, 2020-07-29) -
Hopf Algebras in Combinatorics, Volume 2
[OWP-2020-15] (Mathematisches Forschungsinstitut Oberwolfach, 2020-07-30) -
How Quantum Information Can Improve Social Welfare
[OWP-2020-13] (Mathematisches Forschungsinstitut Oberwolfach, 2020-07-16)In [2, 18, 5, 19, 4] it has been shown that quantum resources can allow us to achieve a family of equilibria that can have sometimes a better social welfare, while guaranteeing privacy. We use graph games to propose ... -
l-Torsion Bounds for the Class Group of Number Fields with an l -Group as Galois Group
[OWP-2020-11] (Mathematisches Forschungsinstitut Oberwolfach, 2020-05-04)We describe the relations among the $\ell$-torsion conjecture for $\ell$-extensions, the discriminant multiplicity conjecture for nilpotent extensions and a conjecture of Malle giving an upper bound for the number of ... -
Maximal Quaternion Orders in Quadratic Extensions - in Hurwitz’s Diaries
[OWP-2020-16] (Mathematisches Forschungsinstitut Oberwolfach, 2020-08-03)We present and comment on some unpublished work of Adolf Hurwitz on quaternion arithmetic from his diaries. -
Multivariate Hybrid Orthogonal Functions
[OWP-2020-04] (Mathematisches Forschungsinstitut Oberwolfach, 2020-03-12)We consider multivariate orthogonal functions satisfying hybrid orthogonality conditions with respect to a moment functional. This kind of orthogonality means that the product of functions of different parity order ... -
Nondegenerate Invariant Symmetric Bilinear Forms on Simple Lie Superalgebras in Characteristic 2
[OWP-2020-02] (Mathematisches Forschungsinstitut Oberwolfach, 2020-02-04)As is well-known, the dimension of the space of non-degenerate invariant symmetric bilinear forms (NISes) on any simple finite-dimensional Lie algebra or Lie superalgebra is equal to at most 1 if the characteristic of the ... -
Nonexistence of Subcritical Solitary Waves
[OWP-2020-06] (Mathematisches Forschungsinstitut Oberwolfach, 2020-03-15)We prove the nonexistence of two-dimensional solitary gravity water waves with subcritical wave speeds and an arbitrary distribution of vorticity. This is a longstanding open problem, and even in the irrotational case there ... -
Octonion Polynomials with Values in a Subalgebra
[OWP-2020-21] (Mathematisches Forschungsinstitut Oberwolfach, 2020-10-22)In this paper, we prove that given an octonion algebra $A$ over a field $F$, a subring $E \subseteq F$ and an octonion $E$-algebra $R$ inside $A$, the set $S$ of polynomials $f(x) \in A[x]$ satisfying $f(R) \subseteq R$ ... -
On Weakly Complete Universal Enveloping Algebras of pro-Lie Algebras
[OWP-2020-10] (Mathematisches Forschungsinstitut Oberwolfach, 2020-04-27) -
The Pelletier-Ressayre Hidden Symmetry for Littlewood-Richardson Coefficients
[OWP-2020-18] (Mathematisches Forschungsinstitut Oberwolfach, 2020-09-08)We prove an identity for Littlewood–Richardson coefficients conjectured by Pelletier and Ressayre. The proof relies on a novel birational involution defined over any semifield. -
Positive Line Bundles Over the Irreducible Quantum Flag Manifolds
[OWP-2020-01] (Mathematisches Forschungsinstitut Oberwolfach, 2020-02-03)Noncommutative Kähler structures were recently introduced by the third author as a framework for studying noncommutative Kähler geometry on quantum homogeneous spaces. It was subsequently observed that the notion of a ... -
Rational Functions with Small Value Set
[OWP-2020-05] (Mathematisches Forschungsinstitut Oberwolfach, 2020-03-14)In connection with Galois Theory and Algebraic Curves, this paper investigates rational functions $h(x) = f(x)/g(x) \in \mathbb{F}_q(x)$ for which the value set $V_h = {\{h(α) | α \in \mathbb{F}_q \cup\{\infty\}}\}$ is ... -
Singularities and Bifurcations of Pseudospherical Surfaces
[OWP-2020-08] (Mathematisches Forschungsinstitut Oberwolfach, 2020-03-17)We study singularities and bifurcations of constant negative curvature surfaces in Euclidean 3-space via their association with Lorentzian harmonic maps. This preprint presents the basic results on this, the full proofs ... -
Space-Time Euler Discretization Schemes for the Stochastic 2D Navier-Stokes Equations
[OWP-2020-12] (Mathematisches Forschungsinstitut Oberwolfach, 2020-05-06)We prove that the implicit time Euler scheme coupled with finite elements space discretization for the 2D Navier-Stokes equations on the torus subject to a random perturbation converges in $L^2(\Omega)$, and describe the ... -
Splitting Necklaces, with Constraints
[OWP-2020-03] (Mathematisches Forschungsinstitut Oberwolfach, 2020-02-11)We prove several versions of Alon's "necklace-splitting theorem", subject to additional constraints, as illustrated by the following results. (1) The "almost equicardinal necklace-splitting theorem" claims that, without ... -
Theoretical Analysis and Simulation Methods for Hawkes Processes and their Diffusion Approximation
[OWP-2020-09] (Mathematisches Forschungsinstitut Oberwolfach, 2020-03-30)Oscillatory systems of interacting Hawkes processes with Erlang memory kernels were introduced in Ditlevsen and Löcherbach (2017). They are piecewise deterministic Markov processes (PDMP) and can be approximated by a ... -
Unexpected Properties of the Klein Configuration of 60 Points in $\mathbb{P}^3$
[OWP-2020-19] (Mathematisches Forschungsinstitut Oberwolfach, 2020-10-07)Felix Klein in course of his study of the regular and its symmetries encountered a highly symmetric configuration of 60 points in $\mathbb{P}^3$. This configuration has appeared in various guises, perhaps post notably as ...