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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 ...
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 ...
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 ...
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 ...
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 ...
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 ...
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 ...
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 ...
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 ...