Browsing 2018 by Title
Now showing items 524 of 29

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 ... 
Exceptional Legendrian Torus Knots
[OWP201804] (Mathematisches Forschungsinstitut Oberwolfach, 20180321)We present classification results for exceptional Legendrian realisations of torus knots. These are the first results of that kind for nontrivial topological knot types. Enumeration results of DingLiZhang concerning ... 
Generalized Vector Cross Products and Killing Forms on Negatively Curved Manifolds
[OWP201817] (Mathematisches Forschungsinstitut Oberwolfach, 20180717)Motivated by the study of Killing forms on compact Riemannian manifolds of negative sectional curvature, we introduce the notion of generalized vector cross products on $\mathbb{R}^n$ and give their classification. Using ... 
Global Variants of Hartogs' Theorem
[OWP201824] (Mathematisches Forschungsinstitut Oberwolfach, 20181106)Hartogs' theorem asserts that a separately holomorphic function, defined on an open subset of $\mathbb{C}^n$, is holomorphic in all the variables. We prove a global variant of this theorem for functions defined on an open ... 
Herbrand’s Theorem as Higher Order Recursion
[OWP201801] (Mathematisches Forschungsinstitut Oberwolfach, 20180219)We provide a means to compute Herbrand disjunctions directly from sequent calculus proofs with cuts. Our approach associates to a firstorder classical proof $\pi \vdash \exists v F$, where $F$ is quantifier free, an ... 
Homogenization of a nonlinear monotone problem with nonlinear Signorini boundary conditions in a domain with highly rough boundary
[OWP201806] (Mathematisches Forschungsinstitut Oberwolfach, 20180416)We consider a domain $\Omega_\varepsilon\subset\mathbb{R}^N$, $N\geq2$, with a very rough boundary depending on~$\varepsilon$. For instance, if $N=3$ the domain $\Omega_\varepsilon$ has the form of a brush with an ... 
The Magic Square of Reflections and Rotations
[OWP201813] (Mathematisches Forschungsinstitut Oberwolfach, 20180701)We show how Coxeter’s work implies a bijection between complex reflection groups of rank two and real reflection groups in 0(3). We also consider this magic square of reflections and rotations in the framework of Clifford ... 
The Martin Boundary of Relatively Hyperbolic Groups with Virtually Abelian Parabolic Subgroups
[OWP201803] (Mathematisches Forschungsinstitut Oberwolfach, 20180319)Given a probability measure on a finitely generated group, its Martin boundary is a way to compactify the group using the Green's function of the corresponding random walk. We give a complete topological characterization ... 
MaxLinear Models on Infinite Graphs Generated by Bernoulli Bond Percolation
[OWP201809] (Mathematisches Forschungsinstitut Oberwolfach, 20180517)We extend previous work of maxlinear models on finite directed acyclic graphs to infinite graphs, and investigate their relations to classical percolation theory. We formulate results for the oriented square lattice graph ... 
A McKay Correspondence for Reflection Groups
[OWP201814] (Mathematisches Forschungsinstitut Oberwolfach, 20180702)We construct a noncommutative desingularization of the discriminant of a finite reflection group $G$ as a quotient of the skew group ring $A=S*G$. If $G$ is generated by order two reflections, then this quotient identifies ... 
Metric Connections with Parallel SkewSymmetric Torsion
[OWP201816] (Mathematisches Forschungsinstitut Oberwolfach, 20180716)A geometry with parallel skewsymmetric torsion is a Riemannian manifold carrying a metric connection with parallel skewsymmetric torsion. Besides the trivial case of the LeviCivita connection, geometries with nonvanishing ... 
MOSES: A Streaming Algorithm for Linear Dimensionality Reduction
[OWP201812] (Mathematisches Forschungsinstitut Oberwolfach, 20180626)This paper introduces Memorylimited Online Subspace Estimation Scheme (MOSES) for both estimating the principal components of data and reducing its dimension. More specifically, consider a scenario where the data vectors ... 
On the Gauss Algebra of Toric Algebras
[OWP201807] (Mathematisches Forschungsinstitut Oberwolfach, 20180425)Let $A$ be a $K$subalgebra of the polynomial ring $S=K[x_1,\ldots,x_d]$ of dimension $d$, generated by finitely many monomials of degree $r$. Then the Gauss algebra $\mathbb{G}(A)$ of $A$ is generated by monomials of ... 
On the Invariants of the Cohomology of Complements of Coxeter Arrangements
[OWP201821] (Mathematisches Forschungsinstitut Oberwolfach, 20181022)We refine Brieskorn's study of the cohomology of the complement of the reflection arrangement of a finite Coxeter group W. As a result we complete the verification of a conjecture by Felder and Veselov that gives an explicit ... 
An Optimal Bound for the Ratio Between Ordinary and Uniform Exponents of Diophantine Approximation
[OWP201815] (Mathematisches Forschungsinstitut Oberwolfach, 20180709)We provide a lower bound for the ratio between the ordinary and uniform exponents of both simultaneous Diophantine approximation to n real numbers and Diophantine approximation for one linear form in n variables. This ... 
Real Analyticity is Concentrated in Dimension 2
[OWP201823] (Mathematisches Forschungsinstitut Oberwolfach, 20181105)We prove that a realvalued function on a real analytic manifold is analytic whenever all its restrictions to $2$dimensional analytic submanifolds are analytic functions. We also obtain analogous results in the framework ... 
Some Results Related to Schiffer's Problem
[OWP201818] (Mathematisches Forschungsinstitut Oberwolfach, 20180816)We consider the following semilinear overdetermined problem on a two dimensional bounded or unbounded domain $\Omega$ with analytic boundary $\partial\Omega$ having at least one bounded connected component \begin{eqnarray*} ...