Now showing items 204-223 of 357

• #### Observability of systems with delay convoluted observation ﻿

[OWP-2014-10] (Mathematisches Forschungsinstitut Oberwolfach, 2014-05-13)
This paper analyzes finite dimensional linear time-invariant systems with observation of a delay, where that delay satisfies a particular implicit relation with the state variables, rendering the entire problem nonlinear. ...
• #### Obtaining Error-Minimizing Estimates and Universal Entry-Wise Error Bounds for Low-Rank Matrix Completion ﻿

[OWP-2013-12] (Mathematisches Forschungsinstitut Oberwolfach, 2013-06-10)
We propose a general framework for reconstructing and denoising single entries of incomplete and noisy entries. We describe: effective algorithms for deciding if and entry can be reconstructed and, if so, for reconstructing ...
• #### 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 a Cheeger Type Inequality in Cayley Graphs of Finite Groups ﻿

[OWP-2019-20] (Mathematisches Forschungsinstitut Oberwolfach, 2019-07-22) - (7 July - 7 October 2017)
Let $G$ be a finite group. It was remarked by Breuillard-Green-Guralnick-Tao that if the Cayley graph $C(G,S)$ is an expander graph and is non-bipartite then the spectrum of the adjacency operator $T$ is bounded away from ...
• #### On a Group Functor Describing Invariants of Algebraic Surfaces ﻿

[OWP-2019-08] (Mathematisches Forschungsinstitut Oberwolfach, 2019-03-01)
Liedtke (2008) has introduced group functors $K$ and $\tilde K$, which are used in the context of describing certain invariants for complex algebraic surfaces. He proved that these functors are connected to the theory of ...
• #### 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 ...
• #### On Canonical Forms for Two-person Zero-sum Limit Average Payoff Stochastic Games ﻿

[OWP-2011-35] (Mathematisches Forschungsinstitut Oberwolfach, 2011-05-29)
We consider two-person zero-sum mean payoff undiscounted stochastic games. We give a sufficient condition for the existence of a saddle point in uniformly optimal stationary strategies. Namely, we obtain sufficient ...
• #### On Co-Minimal Pairs in Abelian Groups ﻿

[OWP-2019-19] (Mathematisches Forschungsinstitut Oberwolfach, 2019-07-09)
A pair of non-empty subsets $(W,W')$ in an abelian group $G$ is a complement pair if $W+W'=G$. $W'$ is said to be minimal to $W$ if $W+(W'\setminus \{w'\}) \neq G, \forall \,w'\in W'$. In general, given an arbitrary subset ...
• #### On commuting varieties of nilradicals of borel subalgebras of reductive lie algebras ﻿

[OWP-2012-14] (Mathematisches Forschungsinstitut Oberwolfach, 2012-12-04)
Let $G$ be a connected reductive algebraic group defined over an algebraically closed field $\mathbb{k}$ of characteristic zero. We consider the commuting variety $\mathcal{C}(\mathfrak{u})$ of the nilradical $\mathfrak{u}$ ...
• #### On Concentrators and Related Approximation Constants ﻿

[OWP-2013-14] (Mathematisches Forschungsinstitut Oberwolfach, 2013-06-10)
Pippenger ([Pip77]) showed the existence of (6m, 4m, 3m, 6)-concentrator for each positive integer m using a probabilistic method. We generalize his approach and prove existence of (6m, 4m, 3m, 5.05)-concentrator (which ...
• #### On conjugacy of MASAs and the outer automorphism group of the Cuntz algebra ﻿

[OWP-2013-21] (Mathematisches Forschungsinstitut Oberwolfach, 2013-10-29)
We investigate the structure of the outer automorphism group of the Cuntz algebra and the closely related problem of conjugacy of MASAa in $\mathcal{O}_n$. In particular, we exhibit an uncountable family of MASAs, conjugate ...
• #### On densities of lattice arrangements intersecting every i-dimensional affine subspace ﻿

[OWP-2016-08] (Mathematisches Forschungsinstitut Oberwolfach, 2016-05-10)
In 1978, Makai Jr. established a remarkable connection between the volume-product of a convex body, its maximal lattice packing density and the minimal density of a lattice arrangement of its polar body intersecting every ...
• #### On Generalizations of Kac-Moody Groups ﻿

[OWP-2010-06] (Mathematisches Forschungsinstitut Oberwolfach, 2010-03-10)
In [7] we define a Curtis-Tits group as a certain generalization of a Kac-Moody group. We distinguish between orientable and non-orientable Curtis-Tits groups and identify all orientable Curtis-Tits groups as Kac-Moody ...
• #### On Local Combinatorial Formulas for Chern Classes of Triangulated Circle Bundle ﻿

[OWP-2016-16] (Mathematisches Forschungsinstitut Oberwolfach, 2016-08-17)
Principal circle bundle over a PL polyhedron can be triangulated and thus obtains combinatorics. The triangulation is assembled from triangulated circle bundles over simplices. To every triangulated circle bundle over a ...
• #### On periodic solutions and global dynamics in a periodic differential delay equation ﻿

[OWP-2014-08] (Mathematisches Forschungsinstitut Oberwolfach, 2014-05-13)
• #### On test sets for nonlinear integer maximization ﻿

[OWP-2007-05] (Mathematisches Forschungsinstitut Oberwolfach, 2007-03-23)
A finite test set for an integer maximation problem enables us to verify whether a feasible point atains the global maximum. We establish in this paper several general results that apply to integer maximization problems ...