Browsing 1  Oberwolfach Preprints (OWP) by Title
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On Dykstra’s Algorithm with Bregman Projections
[OWP202404] (Mathematisches Forschungsinstitut Oberwolfach, 20240416)We provide quantitative results on the asymptotic behavior of Dykstra’s algorithm with Bregman projections, a combination of the wellknown Dykstra’s algorithm and the method of cyclic Bregman projections, designed to find ... 
On Generalizations of KacMoody Groups
[OWP201006] (Mathematisches Forschungsinstitut Oberwolfach, 20100310)In [7] we define a CurtisTits group as a certain generalization of a KacMoody group. We distinguish between orientable and nonorientable CurtisTits groups and identify all orientable CurtisTits groups as KacMoody ... 
On Local Combinatorial Formulas for Chern Classes of Triangulated Circle Bundle
[OWP201616] (Mathematisches Forschungsinstitut Oberwolfach, 20160817)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 Overgroups of Distinguished Unipotent Elements in Reductive Groups and Finite Groups of Lie Type
[OWP202405] (Mathematisches Forschungsinstitut Oberwolfach, 20240618)Suppose G is a simple algebraic group defined over an algebraically closed field of good characteristic p. In 2018 Korhonen showed that if H is a connected reductive subgroup of G which contains a distinguished unipotent ... 
On periodic solutions and global dynamics in a periodic differential delay equation
[OWP201408] (Mathematisches Forschungsinstitut Oberwolfach, 20140513)Several aspects of global dynamics and the existence of periodic solutions are studied for the scalar differential delay equation $x'(t) = a(t)f(x([tK]))$, where $f(x)$ is a continuous negative feedback function, $x \cdot ... 
On Reflection Subgroups of Finite Coxeter Groups
[OWP201106] (Mathematisches Forschungsinstitut Oberwolfach, 2011059)Let $W$ be a finite Coxeter group. We classify the reflection subgroups of $W$ up to conjugacy and give necessary and sufficient conditions for the map that assigns to a reflection subgroup $R$ of $W$ the conjugacy class ... 
On Residuals of Finite Groups
[OWP201917] (Mathematisches Forschungsinstitut Oberwolfach, 20190528)A theorem of Dolfi, Herzog, Kaplan, and Lev [DHKL07, Thm. C] asserts that in a finite group with trivial Fitting subgroup, the size of the soluble residual of the group is bounded from below by a certain power of the group ... 
On Selfinjective Artin Algebras Having Generalized Standard Quasitubes
[OWP201018] (Mathematisches Forschungsinstitut Oberwolfach, 20100318)We give a complete description of the Morita equivalence classes of all connected selfinjective artin algebras for which the AuslanderReiten quiver admits a family of quasitubes having common composition factors, closed ... 
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 test sets for nonlinear integer maximization
[OWP200705] (Mathematisches Forschungsinstitut Oberwolfach, 20070323)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 ... 
On the autonomous metric on groups of Hamiltonian diffeomorphisms of closed hyperbolic surfaces
[OWP201318] (Mathematisches Forschungsinstitut Oberwolfach, 20130723)Let $\Sigma_g$ be a closed hyperbolic surface of genus $g$ and let Ham($\Sigma_ g$) be the group of Hamiltonian diffeomorphisms of $\Sigma_g$. The most natural word metric on this group is the autonomous metric. It has ... 
On the autonomous metric on the group of areapreserving diffeomorphisms of the 2disc
[OWP201216] (Mathematisches Forschungsinstitut Oberwolfach, 2012)Let $D^2$ be the open unit disc in the Euclidean plane and let $G := Diff(D^2; area)$ be the group of smooth compactly supported areapreserving diffeomorphisms of $D^2$. For every natural number $k$ we construct an injective ... 
On the complement of the dense orbit for a quiver of type A
[OWP201011] (Mathematisches Forschungsinstitut Oberwolfach, 2010)Let $\mathbb{A}_t$ be the directed quiver of type $A$ with $t$ vertices. For each dimension vector $d$ there is a dense orbit in the corresponding representation space. The principal aim of this note is to use just rank ... 
On the Complement of the Richardson Orbit
[OWP201009] (Mathematisches Forschungsinstitut Oberwolfach, 20100313)We consider parabolic subgroups of a general algebraic group over an algebraically closed field $k$ whose Levi part has exactly $t$ factors. By a classical theorem of Richardson, the nilradical of a parabolic subgroup $P$ ... 
On the Computational Content of the Theory of Borel Equivalence Relations
[OWP202106] (Mathematisches Forschungsinstitut Oberwolfach, 20210317)This preprint offers computational insights into the theory of Borel equivalence relations. Specifically, we classify equivalence relations on the Cantor space up to computable reductions, i.e., reductions induced by Turing ... 
On the Derived Category of Grassmannians in Arbitrary Characteristic
[OWP201324] (Mathematisches Forschungsinstitut Oberwolfach, 20131209)In this paper we consider Grassmannians in arbitrary characteristic. Generalizing Kapranov's wellknown characteristiczero results we construct dual exceptional collections on them (which are however not strong) as well ... 
On the Directionally Newtonnondegenerate Singularities of Complex Hypersurfaces
[OWP200816] (Mathematisches Forschungsinstitut Oberwolfach, 2008)We introduce a minimal generalization of Newtonnondegenerate singularities of hypersurfaces. Roughly speaking, an isolated hypersurface singularity is called directionally Newtonnondegenerate if the local embedded ... 
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 ... 
On the Enumeration of Finite $L$Algebras
[OWP202211] (Mathematisches Forschungsinstitut Oberwolfach, 20220629)We use Constraint Satisfaction Methods to construct and enumerate finite Lalgebras up to isomorphism. These objects were recently introduced by Rump and appear in Garside theory, algebraic logic, and the study of the ... 
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 ...