2009
2009
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Alternative iterative methods for nonexpansive mappings, rates of convergence and applications
[OWP200919] (Mathematisches Forschungsinstitut Oberwolfach, 2009)Alternative iterative methods for a nonexpansive mapping in a Banach space are proposed and proved to be convergent to a common solution to a fixed point problem and a variational inequality. We give rates of asymptotic ... 
Proof mining in metric fixed point theory and ergodic theory
[OWP200905] (Mathematisches Forschungsinstitut Oberwolfach, 2009)In this survey we present some recent applications of proof mining to the fixed point theory of (asymptotically) nonexpansive mappings and to the metastability (in the sense of Terence Tao) of ergodic averages in uniformly ... 
Minimal Riesz energy on the sphere for axissupported external fields
[OWP200904] (Mathematisches Forschungsinstitut Oberwolfach, 2009)Abstract. We investigate the minimal Riesz $s$energy problem for positive measures on the ddimensional unit sphere $\mathbb{S}^d$ in the presence of an external field induced by a point charge, and more generally by ... 
HeisenbergWeyl algebra revisited: combinatorics of words and paths
[OWP200902] (Mathematisches Forschungsinstitut Oberwolfach, 2009)The Heisenberg–Weyl algebra, which underlies virtually all physical representations of Quantum Theory, is considered from the combinatorial point of view. We provide a concrete model of the algebra in terms of paths on a ... 
Geometric quantization of integrable systems with hyperbolic singularities
[OWP200901] (Mathematisches Forschungsinstitut Oberwolfach, 2009)We construct the geometric quantization of a compact surface using a singular real polarization coming from an integrable system. Such a polarization always has singularities, which we assume to be of nondegenerate type. ... 
Optimal bounds for the colored Tverberg Problem
[OWP200927] (Mathematisches Forschungsinstitut Oberwolfach, 20090320)We prove a "Tverberg type" multiple intersection theorem. It strengthens the prime case of the original Tverberg theorem from 1966, as well as the topological Tverberg theorem of Bárány et al. (1980), by adding color ... 
Weighted Fourier inequalities for radial functions
[OWP200926] (Mathematisches Forschungsinstitut Oberwolfach, 20090319)Weighted $L^p(\mathbb{R}^n) \to L^q(\mathbb{R}^n)$ Fourier inequalities are studied. We prove PittBoas type results on integrability with power weights of the Fourier transform of a radial function. 
A new counting function for the zeros of holomorphic curves
[OWP200925] (Mathematisches Forschungsinstitut Oberwolfach, 20090318)Let $f_1,..., f_p$ be entire functions that do not all vanish at any point, so that $(f_1,..., f_p)$ is a holomorphic curve in $\mathbb{CP}^{p1}$. We introduce a new and more careful notion of counting the order of the ... 
Discrete noncommutative integrability: the proof of a conjecture by M. Kontsevich
[OWP200924] (Mathematisches Forschungsinstitut Oberwolfach, 20090317)We prove a conjecture of Kontsevich regarding the solutions of rank two recursion relations for noncommutative variables which, in the commutative case, reduce to rank two cluster algebras of affine type. The conjecture ... 
On Siegel modular forms of level p and their properties mod p
[OWP200923] (Mathematisches Forschungsinstitut Oberwolfach, 20090316)Using theta series we construct Siegel modular forms of level p which behave well modulo $p$ in all cusps. This construction allows us to show (under a mild condition) that all Siegel modular forms of level p and weight 2 ... 
On the distribution of a second class particle in the asymmetric simple exclusion process
[OWP200922] (Mathematisches Forschungsinstitut Oberwolfach, 20090315)We give an exact expression for the distribution of the position $X(t)$ of a single second class particle in the asymmetric simple exclusion process (ASEP) where initially the second class particle is located at the origin ... 
Positivity of the Tsystem cluster algebra
[OWP200921] (Mathematisches Forschungsinstitut Oberwolfach, 20090314)We give the path model solution for the cluster algebra variables of the $A_r$ Tsystem with generic boundary conditions. The solutions are partition functions of (strongly) nonintersecting paths on weighted graphs. The ... 
Simple vector bundles on plane degenerations of an elliptic curve
[OWP200920] (Mathematisches Forschungsinstitut Oberwolfach, 20090313)In 1957 Atiyah classified simple and indecomposable vector bundles on an elliptic curve. In this article we generalize his classification by describing the simple vector bundles on all reduced plane cubic curves. Our main ... 
The contact polytope of the leech lattice
[OWP200918] (Mathematisches Forschungsinstitut Oberwolfach, 20090312)The contact polytope of a lattice is the convex hull of its shortest vectors. In this paper we classify the facets of the contact polytope of the Leech lattice up to symmetry. There are 1, 197, 362, 269, 604, 214, 277, 200 ... 
Approximation of discrete functions and size of spectrum
[OWP200917] (Mathematisches Forschungsinstitut Oberwolfach, 20090311)Let $\Lambda \subset \mathbb{R}$ be a uniformly discrete sequence and $S \subset \mathbb{R}$ a compact set. We prove that if there exists a bounded sequence of functions in PaleyWiener space $PW_s$, which approximates ... 
Control of Volterra systems with scalar kernels
[OWP200916] (Mathematisches Forschungsinstitut Oberwolfach, 20090310)Volterra observations systems with scalar kernels are studied. New sufficient conditions for admissibility of observation operators are developed and some examples are discussed. 
On the geometry of the space of fibrations
[OWP200915] (Mathematisches Forschungsinstitut Oberwolfach, 20090309)We study geometrical aspects of the space of fibrations between two given manifolds $M$ and $B$, from the point of view of Fréchet geometry. As a first result, we show that any connected component of this space is the ... 
Tilting on noncommutative rational projective curves
[OWP200914] (Mathematisches Forschungsinstitut Oberwolfach, 20090308)In this article we introduce a new class of noncommutative projective curves and show that in certain cases the derived category of coherent sheaves on them has a tilting complex. In particular, we prove that the right ... 
An introduction to heavytailed and sibexponential distributions
[OWP200913] (Mathematisches Forschungsinstitut Oberwolfach, 20090307)This text studies heavytailed distributions in probability theory, and especially convolutions of such distributions. The mail goal is to provide a complete and comprehensive introduction to the theory of longtailed ... 
Simple graded commutative algebras
[OWP200912] (Mathematisches Forschungsinstitut Oberwolfach, 20090306)We study the notion of $\Gamma$graded commutative algebra for an arbitrary abelian group $\Gamma$. The main examples are the Clifford algebras already treated in [2]. We prove that the Clifford algebras are the only ...