• Categorical Linearly Ordered Structures 

      [OWP-2018-08] Downey, Rod; Melnikov, Alexander; Ng, Keng Meng (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 ...
    • A categorical model for the virtual braid group 

      [OWP-2011-19] Kauffman, Louis H.; Lambropoulou, Sofia (Mathematisches Forschungsinstitut Oberwolfach, 2011-05-18)
    • Cauchy Completeness, Lax Epimorphisms and Effective Descent for Split Fibrations 

      [OWP-2023-06] Lucatelli Nunes, Fernando; Prezado, Rui; Sousa, Lurdes (Mathematisches Forschungsinstitut Oberwolfach, 2023-06-19)
      For any suitable base category $\mathcal{V} $, we find that $\mathcal{V} $-fully faithful lax epimorphisms in $\mathcal{V} $-$\mathsf{Cat} $ are precisely those $\mathcal{V}$-functors $F \colon \mathcal{A} \to \mathcal{B}$ ...
    • Central Limit Theorems for the Radial Spanning Tree 

      [OWP-2014-18] Schulte, Matthias; Thäle, Christoph (Mathematisches Forschungsinstitut Oberwolfach, 2014)
      Consider a homogeneous Poisson point process in a compact convex set in d-dimensional Euclidean space which has interior points and contains the origin. The radial spanning tree is constructed by connecting each point of ...
    • The Character Triple Conjecture for Maximal Defect Characters and the Prime 2 

      [OWP-2023-15] Rossi, Damiano (Mathematisches Forschungsinstitut Oberwolfach, 2023-08-22)
      We prove that Späth’s Character Triple Conjecture holds for every finite group with respect to maximal defect characters at the prime 2. This is done by reducing the maximal defect case of the conjecture to the so-called ...
    • A Characterization of Semisimple Plane Polynomial Automorphisms 

      [OWP-2008-08] Maubach, Stefan; Furter, Jean-Philippe (Mathematisches Forschungsinstitut Oberwolfach, 2008-03-12)
      It is well-known that an element of the linear group $GL_n(\mathbb{C})$ is semisimple if and only if its conjugacy class is Zariski closed. The aim of this paper is to show that the same result holds for the group of complex ...
    • Characterization of Tropical Planar Curves up to Genus Six 

      [OWP-2022-06] Tewari, Ayush Kumar (Mathematisches Forschungsinstitut Oberwolfach, 2022-03-16)
      We provide new forbidden criterion for realizability of smooth tropical plane curves. This in turn provides us a complete classification of smooth tropical plane curves up to genus six.
    • A Cheeger Type Inequality in Finite Cayley Sum Graphs 

      [OWP-2019-21] Biswas, Arindam; Saha, Jyoti Prakash (Mathematisches Forschungsinstitut Oberwolfach, 2019-07-31) - (5 May - 27 July 2019)
      Let $G$ be a finite group and $S$ be a symmetric generating set of $G$ with $|S| = d$. We show that if the undirected Cayley sum graph $C_{\Sigma}(G,S)$ is an expander graph and is non-bipartite, then the spectrum of its ...
    • Chirality of Real Non-Singular Cubic Fourfolds and Their Pure Deformation Classification 

      [OWP-2019-14] Finashin, Sergey; Kharlamov, Viatcheslav (Mathematisches Forschungsinstitut Oberwolfach, 2019-05-15)
      In our previous works we have classified real non-singular cubic hypersurfaces in the 5-dimensional projective space up to equivalence that includes both real projective transformations and continuous variations of ...
    • Classification of idempotent states on the compact quantum groups Uq(2), SUq(2) and SOq(3) 

      [OWP-2009-08] Franz, Uwe; Skalski, Adam; Tomatsu, Reiji (Mathematisches Forschungsinstitut Oberwolfach, 2009-03-02)
      We give a simple characterisation of those idempotent states on compact quantum groups which arise as Haar states on quantum subgroups, show that all idempotent states on quantum groups $U_q(2)$, $SU_q(2)$, and $SO_q(3) ...
    • Classification of totally real elliptic Lefschetz fibrations via necklace diagrams 

      [OWP-2011-13] Salepci, Nermin (Mathematisches Forschungsinstitut Oberwolfach, 2011)
      We show that totally real elliptic Lefschetz brations that admit a real section are classified by their "real loci" which is nothing but an $S^1$-valued Morse function on the real part of the total space. We assign to ...
    • The Cleavage Operad and String Topology of Higher Dimension 

      [OWP-2011-37] Bargheer, Tarje (Mathematisches Forschungsinstitut Oberwolfach, 2011)
    • Cluster structures on simple complex lie groups and the Belavin-Drinfeld classification 

      [OWP-2011-10] Gekhtman, Michael; Shapiro, Michael; Vainshtein, Alek (Mathematisches Forschungsinstitut Oberwolfach, 2011-05-12)
      We study natural cluster structures in the rings of regular functions on simple complex Lie groups and Poisson-Lie structutures compatible with these cluster structures. According to our main conjecture, each class in the ...
    • Cocharacter-closure and spherical buildings 

      [OWP-2015-12] Bate, Michael; Herpel, Sebastian; Martin, Benjamin; Röhrle, Gerhard (Mathematisches Forschungsinstitut Oberwolfach, 2015-07-29)
      Let $k$ be a field, let $G$ be a reductive $k$-group and $V$ an affine $k$-variety on which $G$ acts. In this note we continue our study of the notion of cocharacter-closed $G(k)$-orbits in $V$. In earlier work we used a ...
    • Cocharacter-Closure and the Rational Hilbert-Mumford Theorem 

      [OWP-2014-16] Bate, Michael; Herpel, Sebastian; Martin, Benjamin; Röhrle, Gerhard (Mathematisches Forschungsinstitut Oberwolfach, 2014-12-20)
      For a field $k$, let $G$ be a reductive $k$-group and $V$ an affine $k$-variety on which $G$ acts. Using the notion of cocharacter-closed $G(k)$-orbits in $V$ , we prove a rational version of the celebrated Hilbert-Mumford ...
    • Cocycle Superrigidity and Group Actions on Stably Finite C*-Algebras 

      [OWP-2017-01] Gardella, Eusebio; Lupini, Martino (Mathematisches Forschungsinstitut Oberwolfach, 2017-01-17)
      Let $\Lambda $ be a countably infinite property (T) group, and let $D$ be UHF-algebra of infinite type. We prove that there exists a continuum of pairwise non (weakly) cocycle conjugate, strongly outer actions of $\Lambda ...
    • The Colored Jones Polynomial and Kontsevich-Zagier Series for Double Twist Knots 

      [OWP-2017-29] Lovejoy, Jeremy; Osburn, Robert (Mathematisches Forschungsinstitut Oberwolfach, 2017-10-20)
      Using a result of Takata, we prove a formula for the colored Jones polynomial of the double twist knots $K_{(-m,-p)}$ and $K_{(-m,p)}$ where $m$ and $p$ are positive integers. In the $(-m,-p)$ case, this leads to new ...
    • Combinatorics of Vassiliev invariants 

      [OWP-2011-22] Chmutov, Sergei (Mathematisches Forschungsinstitut Oberwolfach, 2011-05-20)
      This paper is an introductory survey of the combinatorial aspects of the Vassiliev theory of knot invariants following the lectures delivered at the Advanced School on Knot Theory and its Applications to Physics and Biology ...
    • Commuting Differential Operators and Higher-dimensional Algebraic Varieties 

      [OWP-2012-02] Kurke, Herbert; Osipov, Denis; Zheglov, Alexander (Mathematisches Forschungsinstitut Oberwolfach, 2012-03-20)
      Several algebro-geometric properties of commutative rings of partial differential operators as well as several geometric constructions are investigated.
    • Composition of Irreducible Morphisms in Coils 

      [OWP-2017-32] Chaio, Claudia; Malicki, Piotr (Mathematisches Forschungsinstitut Oberwolfach, 2017-10-30)
      We study the non-zero composition of n irreducible morphisms between modules lying in coils in relation with the powers of the radical of their module category.