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Now showing items 11-20 of 36
Abstract Bivariant Cuntz Semigroups
[OWP-2017-04] (Mathematisches Forschungsinstitut Oberwolfach, 2017-02-13)
We show that abstract Cuntz semigroups form a closed symmetric monoidal category. Thus, given Cuntz semigroups $S$ and $T$, there is another Cuntz semigroup $((S,T))$ playing the role of morphisms from $S$ to $T$. Applied ...
On Vietoris-Rips Complexes of Ellipses
[OWP-2017-11] (Mathematisches Forschungsinstitut Oberwolfach, 2017-04-25)
For $X$ a metric space and $r > 0$ a scale parameter, the Vietoris–Rips complex $VR_<(X; r)$
(resp. $VR_≤(X; r)$) has $X$ as its vertex set, and a finite subset $\sigma \subseteq X$ as a simplex whenever the
diameter of ...
Linear Syzygies, Hyperbolic Coxeter Groups and Regularity
[OWP-2017-15] (Mathematisches Forschungsinstitut Oberwolfach, 2017-05-24)
We build a new bridge between geometric group theory and commutative algebra by showing that the virtual cohomological dimension of a Coxeter group is essentially the regularity of the Stanley–Reisner ring of its nerve. ...
An Extension Problem and Trace Hardy Inequality for the Sublaplacian on H-Type Groups
[OWP-2017-20] (Mathematisches Forschungsinstitut Oberwolfach, 2017-07-24)
In this paper we study the extension problem for the sublaplacian on a H-type group and use the solutions to prove trace Hardy and Hardy inequalities for fractional powers of the sublaplacian.
Cocycle Superrigidity and Group Actions on Stably Finite C*-Algebras
[OWP-2017-01] (Mathematisches Forschungsinstitut Oberwolfach, 2017-01-17)
Let $\Lambda $ be a countably infinite property (T) group, and let $D$ be
UHF-algebra of infinite type. We prove that there exists a continuum of
pairwise non (weakly) cocycle conjugate, strongly outer actions of $\Lambda ...
Matrix Elements of Irreducible Representations of SU(n+1) x SU(n+1) and Multivariable Matrix-Valued Orthogonal Polynomials
[OWP-2017-16] (Mathematisches Forschungsinstitut Oberwolfach, 2017-06-14)
In Part 1 we study the spherical functions on compact symmetric pairs of arbitrary
rank under a suitable multiplicity freeness assumption and additional conditions
on the branching rules. The spherical functions are ...
GAP Functionality for Zariski Dense Groups
[OWP-2017-22] (Mathematisches Forschungsinstitut Oberwolfach, 2017-09-14)
In this document we describe the functionality of GAP [4] routines for Zariski dense or arithmetic groups that are developed in [1, 2, 3]. The research underlying the software was supported through the programme "Research ...
Geometry of Free Loci and Factorization of Noncommutative Polynomials
[OWP-2017-23] (Mathematisches Forschungsinstitut Oberwolfach, 2017-10-02)
The free singularity locus of a noncommutative polynomial f is defined to be the sequence $Z_n(f)=\{X\in M_n^g : \det f(X)=0\}$ of hypersurfaces. The main theorem of this article shows that f is irreducible if and only if ...
Holonomy Groups of $G_2^*$-Manifolds
[OWP-2017-07] (Mathematisches Forschungsinstitut Oberwolfach, 2017-03-07)
We classify the holonomy algebras of manifolds admitting an indecomposable torsion free $G_2^*$-structure, i.e. for which the holonomy representation does not leave invariant any proper non-degenerate subspace. We realize ...
On an Effective Variation of Kronecker’s Approximation Theorem Avoiding Algebraic Sets
[OWP-2017-28] (Mathematisches Forschungsinstitut Oberwolfach, 2017-10-19)
Let $\Lambda \subset \mathbb R^n$ be an algebraic lattice, coming from a projective module over the ring of integers of a number field $K$. Let $\mathcal Z \subset \mathbb R^n$ be the zero locus of a finite collection of ...