Browsing 1  Oberwolfach Preprints (OWP) by Title
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Composition of Irreducible Morphisms in QuasiTubes
[OWP201503] (Mathematisches Forschungsinstitut Oberwolfach, 20150409)We study the composition of irreducible morphisms between indecomposable modules lying in quasitubes of the AuslanderReiten quivers of artin algebras $A$ in relation with the powers of the radical of their module category ... 
Computing Congruence Quotients of Zariski Dense Subgroups
[OWP201822] (Mathematisches Forschungsinstitut Oberwolfach, 20181026)We obtain a computational realization of the strong approximation theorem. That is, we develop algorithms to compute all congruence quotients modulo rational primes of a finitely generated Zariski dense group $H \leq ... 
Congruences Associated with Families of Nilpotent Subgroups and a Theorem of Hirsch
[OWP201916] (Mathematisches Forschungsinstitut Oberwolfach, 20190527)Our main result associates a family of congruences with each suitable system of nilpotent subgroups of a finite group. Using this result, we complete and correct the proof of a theorem of Hirsch concerning the class number ... 
A construction of hyperbolic Coxeter groups
[OWP201004] (Mathematisches Forschungsinstitut Oberwolfach, 2010)We give a simple construction of Gromov hyperbolic Coxeter groups of arbitrarily large virtual cohomological dimension. Our construction provides new examples of such groups. Using this one can construct e.g. new groups ... 
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 ... 
Contractive Idempotents on Locally Compact Quantum Groups
[OWP201219] (Mathematisches Forschungsinstitut Oberwolfach, 2012)A general form of contractive idempotent functionals on coamenable locally compact quantum groups is obtained, generalising the result of Greenleaf on contractive measures on locally compact groups. The image of a convolution ... 
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. 
Counting Curves on Toric Surfaces Tropical Geometry & the Fock Space
[OWP201718] (Mathematisches Forschungsinstitut Oberwolfach, 20170717)We study the stationary descendant Gromov–Witten theory of toric surfaces by combining and extending a range of techniques – tropical curves, floor diagrams, and Fock spaces. A correspondence theorem is established between ... 
Coxeter Arrangements and Solomon's Descent Algebra
[OWP201103] (Mathematisches Forschungsinstitut Oberwolfach, 2011056) 
Criteria for Algebraicity of Analytic Functions
[OWP201825] (Mathematisches Forschungsinstitut Oberwolfach, 20181112)We consider functions defined on an open subset of a nonsingular, either real or complex, algebraic set. We give criteria for an analytic function to be a Nash (resp. regular, resp. polynomial) function. Our criteria depend ... 
Cryptanalysis of Publickey Cryptosystems Based on Algebraic Geometry Codes
[OWP201201] (Mathematisches Forschungsinstitut Oberwolfach, 20120320)This paper addresses the question of retrieving the triple $(\mathcal{X},\mathcal{P},\mathcal{E})$ from the algebraic geometry code $\mathcal{C}_L(\mathcal{X},\mathcal{P},\mathcal{E})$, where $\mathcal{X}$ is an algebraic ... 
Crystal energy functions via the charge in types A and C
[OWP201125] (Mathematisches Forschungsinstitut Oberwolfach, 20110523)The RamYip formula for Macdonald polynomials (at $t=0$) provides a statistic which we call charge. In types $A$ and $C$ it can be defined on tensor products of KashiwaraNakashima single column crystals. In this ... 
Definable orthogonality classes in accessible categories are small
[OWP201114] (Mathematisches Forschungsinstitut Oberwolfach, 20110515)We lower substantially the strength of the assumptions needed for the validity of certain results in category theory and homotopy theory which were known to follow from Vopenka's principle. We prove that the necessary ... 
Deformation Classification of Real NonSingular Cubic Threefolds with a Marked Line
[OWP201802] (Mathematisches Forschungsinstitut Oberwolfach, 20180221)We prove that the space of pairs $(X,l)$ formed by a real nonsingular cubic hypersurface $X\subset P^4$ with a real line $l\subset X$ has 18 connected components and give for them several quite explicit interpretations. ... 
A Deformed Quon Algebra
[OWP201811] (Mathematisches Forschungsinstitut Oberwolfach, 20180625)The quon algebra is an approach to particle statistics in order to provide a theory in which the Pauli exclusion principle and Bose statistics are violated by a small amount. The quons are particles whose annihilation and ... 
Demailly’s Notion of Algebraic Hyperbolicity: Geometricity, Boundedness, Moduli of Maps
[OWP201820] (Mathematisches Forschungsinstitut Oberwolfach, 20181008)Demailly's conjecture, which is a consequence of the GreenGriffithsLang conjecture on varieties of general type, states that an algebraically hyperbolic complex projective variety is Kobayashi hyperbolic. Our aim is to ... 
Demailly’s Notion of Algebraic Hyperbolicity: Geometricity, Boundedness, Moduli of Maps (Revised Edition)
[OWP201820.2] (Mathematisches Forschungsinstitut Oberwolfach, 20200123)Demailly's conjecture, which is a consequence of the GreenGriffthsLang conjecture on varieties of general type, states that an algebraically hyperbolic complex projective variety is Kobayashi hyperbolic. Our aim is to ... 
Detecting Ineffective Features for Pattern Recognition
[OWP201726] (Mathematisches Forschungsinstitut Oberwolfach, 20171017)For a binary classification problem, the hypothesis testing is studied, that a component of the observation vector is not effective, i.e., that component carries no information for the classification. We introduce nearest ... 
Dirichlet Approximation and Universal Dirichlet
[OWP201612] (Mathematisches Forschungsinstitut Oberwolfach, 20160816)We characterize the uniform limits of Dirichlet polynomials on a right half plane. We extend the approximation theorems of Runge, Mergelyan and Vitushkin to the Dirichlet setting with respect to the Euclidean distance and ... 
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 ...