• The Varchenko Determinant of a Coxeter Arrangement 

      [OWP-2017-33] Pfeiffer, Götz; Randriamaro, Hery (Mathematisches Forschungsinstitut Oberwolfach, 2017-11-24)
      The Varchenko determinant is the determinant of a matrix defined from an arrangement of hyperplanes. Varchenko proved that this determinant has a beautiful factorization. It is, however, not possible to use this factorization ...
    • Varieties of Invariant Subspaces Given by Littlewood-Richardson Tableaux 

      [OWP-2014-01] Kosakowska, Justyna; Schmidmeier, Markus (Mathematisches Forschungsinstitut Oberwolfach, 2014-04-25)
      Given partitions $\alpha, \beta, \gamma$, the short exact sequences $0 \rightarrow N_\alpha \rightarrow N_\beta \rightarrow N_\gamma \rightarrow 0$ of nilpotent linear operators of Jordan types $\alpha, \beta, \gamma$, ...
    • Vector bundles on degenerations of elliptic curves and Yang-Baxter equations 

      [OWP-2007-04] Burban, Igor; Kreußler, Bernd (Mathematisches Forschungsinstitut Oberwolfach, 2007-03-22)
      In this paper we introduce the notion of a gemetric associative r-matrix attached to a genus one fibration with a section and irreducible fibres. It allows us to study degenerations of solutions of the classical Yang-Baxter ...
    • Very general monomial valuations of P2 and a Nagata type conjecture 

      [OWP-2013-22] Dumnicki, Marcin; Harbourne, Brian; Küronya, Alex; Roé, Joaquim; Szemberg, Tomasz (Mathematisches Forschungsinstitut Oberwolfach, 2013-10-29)
    • Virtual Polytopes 

      [OWP-2015-02] Panina, Gaiane; Streinu, Ileana (Mathematisches Forschungsinstitut Oberwolfach, 2015-04-10)
      Originating in diverse branches of mathematics, from polytope algebra and toric varieties to the theory of stressed graphs, virtual polytopes represent a natural algebraic generalization of convex polytopes. Introduced as ...
    • Visual analysis of Spanish male mortality 

      [SNAP-2015-012-ENSNAP-2015-012-DE] Marron, J. S. (Mathematisches Forschungsinstitut Oberwolfach, 2015)
      [also available in German] Statistical visualization uses graphical methods to gain insights from data. Here we show how a technique called principal component analysis is used to analyze mortality in Spain over about the ...
    • Weak Expansiveness for Actions of Sofic Groups 

      [OWP-2014-05] Chung, Nhan-Phu; Zhang, Guohua (Mathematisches Forschungsinstitut Oberwolfach, 2014-04-25)
      In this paper, we shall introduce $h$-expansiveness and asymptotical $h$-expansiveness for actions of sofic groups. By the definitions, each h-expansive action of sofic groups is asymptotically $h$-expansive. We show that ...
    • Weak-duality based adaptive finite element methods for PDE-constrained optimization with pointwise gradient state-constraints 

      [OWP-2010-15] Hintermüller, Michael; Hinze, Michael; Hoppe, Ronald H. W. (Mathematisches Forschungsinstitut Oberwolfach, 2010)
      Adaptive finite element methods for optimization problems for second order linear elliptic partial di erential equations subject to pointwise constraints on the $\ell^2$-norm of the gradient of the state are considered. ...
    • Weakly Complex Homogeneous Spaces 

      [OWP-2012-04] Moroianu, Andrei; Semmelmann, Uwe (Mathematisches Forschungsinstitut Oberwolfach, 2012-04-24)
      We complete our recent classification of compact inner symmetric spaces with weakly complex tangent bundle by filling up a case which was left open, and extend this classification to the larger category of compact homogeneous ...
    • Weighted Fourier inequalities for radial functions 

      [OWP-2009-26] Gorbachev, D.; Liflyand, E.; Tichonovič, S. V. (Mathematisches Forschungsinstitut Oberwolfach, 2009-03-19)
      Weighted $L^p(\mathbb{R}^n) \to L^q(\mathbb{R}^n)$ Fourier inequalities are studied. We prove Pitt-Boas type results on integrability with power weights of the Fourier transform of a radial function.
    • A Well-Posedness Result for Viscous Compressible Fluids with Only Bounded Density 

      [OWP-2018-10] Danchin, Raphaël; Fanelli, Francesco; Paicu, Marius (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 ...
    • Wer ist Alexander Grothendieck? 

      Scharlau, Winfried (Mathematisches Forschungsinstitut Oberwolfach, 2006)
      The Oberwolfach Lecture "Wer ist Alexander Grothendieck" (in German) was held by Prof. Dr. Winfried Scharlau as a public lecture on occasion of the annual meeting of the Gesellschaft für Mathematische Forschung e.V. 2006 ...
    • The Weyl group of the Curtz algebra 

      [OWP-2011-31] Conti, Roberto; Hong, Jeong Hee; Szymański, Wojciech (Mathematisches Forschungsinstitut Oberwolfach, 2011-05-28)
      The Weyl group of the Cuntz algebra $\mathcal{O}_n$ is investigated. This is (isomorphic to) the group of polynomial automorphisms $\lambda_u$ of $\mathcal{O}_n$, namely those induced by unitaries u that can be written ...
    • Weyl-Titchmarsh Functions of Vector-Valued Sturm-Liouville Operators on the Unit Interval 

      [OWP-2008-13] Chelkak, Dmitry; Korotyaev, Evgeny (Mathematisches Forschungsinstitut Oberwolfach, 2008)
      The matrix-valued Weyl-Titchmarsh functions $M(\lambda)$ of vector-valued Sturm-Liouville operators on the unit interval with the Dirichlet boundary conditions are considered. The collection of the eigenvalues (i.e., poles ...
    • What does ">" really mean? 

      [SNAP-2014-004-EN] Reznick, Bruce (Mathematisches Forschungsinstitut Oberwolfach, 2014)
      This Snapshot is about the generalization of ">" from ordinary numbers to so-called fields. At the end, I will touch on some ideas in recent research.
    • Wie steuert man einen Kran? 

      [SNAP-2016-007-DE] Altmann, Robert; Heiland, Jan (Mathematisches Forschungsinstitut Oberwolfach, 2016)
      Die Steuerung einer Last an einem Kran ist ein technisch und mathematisch schwieriges Problem, da die Bewegung der Last nur indirekt beeinflusst werden kann. Anhand eines Masse-Feder-Systems illustrieren wir diese ...
    • The Willmore Conjecture 

      [SNAP-2016-011-EN] Nowaczyk, Nikolai (Mathematisches Forschungsinstitut Oberwolfach, 2016)
      The Willmore problem studies which torus has the least amount of bending energy. We explain how to think of a torus as a donut-shaped surface and how the intuitive notion of bending has been studied by mathematics over time.
    • Winkeltreue zahlt sich aus 

      [SNAP-2017-001-DE] Günther, Felix (Mathematisches Forschungsinstitut Oberwolfach, 2017-08-23)
      Nicht nur Seefahrerinnen, auch Computergrafikerinnen und Physikerinnen wissen Winkeltreue zu schätzen. Doch beschränkte Rechenkapazitäten und Vereinfachungen in theoretischen Modellen erfordern es, winkeltreue Abbildungen ...
    • Yet another algorithm for the symmetric eigenvalue problem 

      [OWP-2016-02] Aurentz, Jared L.; Mach, Thomas; Vandebril, Raf; Watkins, David S. (Mathematisches Forschungsinstitut Oberwolfach, 2016-05-10)
      In this paper we present a new algorithm for solving the symmetric matrix eigenvalue problem that works by first using a Cayley transformation to convert the symmetric matrix into a unitary one and then uses Gragg’s ...
    • Z2-Thurston Norm and Complexity of 3-Manifolds, II 

      [OWP-2017-36] Jaco, William; Rubinstein, J. Hyam; Spreer, Jonathan; Tillmann, Stephan (Mathematisches Forschungsinstitut Oberwolfach, 2017-12-20)
      In this sequel to earlier papers by three of the authors, we obtain a new bound on the complexity of a closed 3-manifold, as well as a characterisation of manifolds realising our complexity bounds. As an application, we ...