Now showing items 1-20 of 29

• Herbrand’s Theorem as Higher Order Recursion ﻿

[OWP-2018-01] (Mathematisches Forschungsinstitut Oberwolfach, 2018-02-19)
We provide a means to compute Herbrand disjunctions directly from sequent calculus proofs with cuts. Our approach associates to a first-order classical proof $\pi \vdash \exists v F$, where $F$ is quantifier free, an ...
• Deformation Classification of Real Non-Singular Cubic Threefolds with a Marked Line ﻿

[OWP-2018-02] (Mathematisches Forschungsinstitut Oberwolfach, 2018-02-21)
We prove that the space of pairs $(X,l)$ formed by a real non-singular 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. ...
• The Martin Boundary of Relatively Hyperbolic Groups with Virtually Abelian Parabolic Subgroups ﻿

[OWP-2018-03] (Mathematisches Forschungsinstitut Oberwolfach, 2018-03-19)
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 ...
• Exceptional Legendrian Torus Knots ﻿

[OWP-2018-04] (Mathematisches Forschungsinstitut Oberwolfach, 2018-03-21)
We present classification results for exceptional Legendrian realisations of torus knots. These are the first results of that kind for non-trivial topological knot types. Enumeration results of Ding-Li-Zhang concerning ...
• The Sylow Structure of Scalar Automorphism Groups ﻿

[OWP-2018-05] (Mathematisches Forschungsinstitut Oberwolfach, 2018-03-22)
For any locally compact abelian periodic group A its automorphism group contains as a subgroup those automorphisms that leave invariant every closed subgroup of A, to be denoted by SAut(A). This subgroup is again a locally ...
• Homogenization of a nonlinear monotone problem with nonlinear Signorini boundary conditions in a domain with highly rough boundary ﻿

[OWP-2018-06] (Mathematisches Forschungsinstitut Oberwolfach, 2018-04-16)
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 ...
• On the Gauss Algebra of Toric Algebras ﻿

[OWP-2018-07] (Mathematisches Forschungsinstitut Oberwolfach, 2018-04-25)
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 ...
• Categorical Linearly Ordered Structures ﻿

[OWP-2018-08] (Mathematisches Forschungsinstitut Oberwolfach, 2018-04-26)
We prove that for every computable limit ordinal $\alpha$ there exists a computable linear ordering $\mathcal{A}$ which is $\Delta^0_\alpha$-categorical and $\alpha$ is smallest such, but nonetheless for every isomorphic ...
• Max-Linear Models on Infinite Graphs Generated by Bernoulli Bond Percolation ﻿

[OWP-2018-09] (Mathematisches Forschungsinstitut Oberwolfach, 2018-05-17)
We extend previous work of max-linear 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 Well-Posedness Result for Viscous Compressible Fluids with Only Bounded Density ﻿

[OWP-2018-10] (Mathematisches Forschungsinstitut Oberwolfach, 2018-05-28)
We are concerned with the existence and uniqueness of solutions with only bounded density for the barotropic compressible Navier-Stokes equations. Assuming that the initial velocity has slightly sub-critical regularity and ...
• A Deformed Quon Algebra ﻿

[OWP-2018-11] (Mathematisches Forschungsinstitut Oberwolfach, 2018-06-25)
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 ...
• MOSES: A Streaming Algorithm for Linear Dimensionality Reduction ﻿

[OWP-2018-12] (Mathematisches Forschungsinstitut Oberwolfach, 2018-06-26)
This paper introduces Memory-limited 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 ...
• The Magic Square of Reflections and Rotations ﻿

[OWP-2018-13] (Mathematisches Forschungsinstitut Oberwolfach, 2018-07-01)
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 ...
• A McKay Correspondence for Reflection Groups ﻿

[OWP-2018-14] (Mathematisches Forschungsinstitut Oberwolfach, 2018-07-02)
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 ...
• An Optimal Bound for the Ratio Between Ordinary and Uniform Exponents of Diophantine Approximation ﻿

[OWP-2018-15] (Mathematisches Forschungsinstitut Oberwolfach, 2018-07-09)
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 ...
• Metric Connections with Parallel Skew-Symmetric Torsion ﻿

[OWP-2018-16] (Mathematisches Forschungsinstitut Oberwolfach, 2018-07-16)
A geometry with parallel skew-symmetric torsion is a Riemannian manifold carrying a metric connection with parallel skew-symmetric torsion. Besides the trivial case of the Levi-Civita connection, geometries with non-vanishing ...
• Generalized Vector Cross Products and Killing Forms on Negatively Curved Manifolds ﻿

[OWP-2018-17] (Mathematisches Forschungsinstitut Oberwolfach, 2018-07-17)
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 ...
• Some Results Related to Schiffer's Problem ﻿

[OWP-2018-18] (Mathematisches Forschungsinstitut Oberwolfach, 2018-08-16)
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*} ...
• Affine Space Fibrations ﻿

[OWP-2018-19] (Mathematisches Forschungsinstitut Oberwolfach, 2018-09-05)
We discuss various aspects of affine space fibrations. Our interest will be focused in the singular fibers, the generic fiber and the propagation of properties of a given smooth special fiber to nearby fibers.
• Demailly’s Notion of Algebraic Hyperbolicity: Geometricity, Boundedness, Moduli of Maps ﻿

[OWP-2018-20] (Mathematisches Forschungsinstitut Oberwolfach, 2018-10-08)
Demailly's conjecture, which is a consequence of the Green-Griffiths-Lang conjecture on varieties of general type, states that an algebraically hyperbolic complex projective variety is Kobayashi hyperbolic. Our aim is to ...