• Supertropical Quadratic Forms I 

      [OWP-2013-27] Knebusch, Manfred; Rowen, Louis; Izhakian, Zur (Mathematisches Forschungsinstitut Oberwolfach, 2013)
      We initiate the theory of a quadratic form q over a semiring $R$. As customary, one can write $q(x+y)=q(x)+q(y)+b(x,y)$, where b is a companion bilinear form. But in contrast to the ring-theoretic case, the companion ...
    • Supertropical semirings and supervaluations 

      [OWP-2010-05] Izhakian, Zur; Knebusch, Manfred; Rowen, Louis (Mathematisches Forschungsinstitut Oberwolfach, 2010)
      We interpret a valuation $\upsilon$ on a ring $R$ as a map $\upsilon:R \rightarrow M$ into a so called bipotent semiring $M$ (the usual max-plus setting), and then define a supervaluation $\varphi$ as a suitable map into ...
    • Sur le Minimum de la Fonction de Brjuno 

      [OWP-2018-26] Balazard, Michel; Martin, Bruno (Mathematisches Forschungsinstitut Oberwolfach, 2018-12-11)
      The Brjuno function attains a strict global minimum at the golden section.
    • The Sylow Structure of Scalar Automorphism Groups 

      [OWP-2018-05] Herfort, Wolfgang; Hofmann, Karl Heinrich; Kramer, Linus; Russo, Francesco G. (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 ...
    • The T-Graph of a Multigraded Hilbert Scheme 

      [OWP-2011-34] Hering, Milena; Maclagan, Diane (Mathematisches Forschungsinstitut Oberwolfach, 2011)
      The $T$-graph of a multigraded Hilbert scheme records the zero and one-dimensional orbits of the $T=(K^*)^n$ action on the Hilbert scheme induced from the $T$-action on $\mathbb{A}^n$. It has vertices the $T$-fixed points, ...
    • Tensor Representations of q(∞) 

      [OWP-2016-09] Grantcharov, Dimitar; Serganova, Vera (Mathematisches Forschungsinstitut Oberwolfach, 2016-06-17)
      We introduce a symmetric monoidal category of modules over the direct limit queer superalgebra $\mathfrak{q}(\infty)$. The category can be defined in two equivalent ways with the aid of the large annihilator condition. ...
    • Theoretical Analysis and Simulation Methods for Hawkes Processes and their Diffusion Approximation 

      [OWP-2020-09] Chevallier, Julien; Melnykova, Anna; Tubikanec, Irene (Mathematisches Forschungsinstitut Oberwolfach, 2020-03-30)
      Oscillatory systems of interacting Hawkes processes with Erlang memory kernels were introduced in Ditlevsen and Löcherbach (2017). They are piecewise deterministic Markov processes (PDMP) and can be approximated by a ...
    • There is a unique real tight contact 3-ball 

      [OWP-2010-01] Öztürk, Ferit; Salepci, Nermin (Mathematisches Forschungsinstitut Oberwolfach, 2010)
      We prove that there is a unique real tight contact structure on the 3-ball with convex boundary up to isotopy through real tight contact structures. We also give a partial classification of the real tight solid tori with ...
    • Tilting on non-commutative rational projective curves 

      [OWP-2009-14] Burban, Igor; Drozd, Jurij A. (Mathematisches Forschungsinstitut Oberwolfach, 2009-03-08)
      In this article we introduce a new class of non-commutative projective curves and show that in certain cases the derived category of coherent sheaves on them has a tilting complex. In particular, we prove that the right ...
    • Time and band limiting for matrix valued functions, an example 

      [OWP-2015-08] Grünbaum, F. A.; Pacharoni, I.; Zurrián, Ignacio Nahuel (Mathematisches Forschungsinstitut Oberwolfach, 2015-07-29)
      The main purpose of this paper is to extend to a situation involving matrix valued orthogonal polynomials and spherical functions, a result that traces its origin and its importance to work of Claude Shannon in laying the ...
    • Time Discretization Schemes for Hyperbolic Systems on Networks by ε-Expansion 

      [OWP-2019-03] Altmann, Robert; Zimmer, Christoph (Mathematisches Forschungsinstitut Oberwolfach, 2019-02-12)
      We consider partial differential equations on networks with a small parameter $\epsilon$, which are hyperbolic for $\epsilon>0$ and parabolic for $\epsilon=0$. With a combination of an $\epsilon$-expansion and Runge-Kutta ...
    • Torsion-free Covers of Solvable Minimax Groups 

      [OWP-2015-15] Kropholler, Peter H.; Lorensen, Karl (Mathematisches Forschungsinstitut Oberwolfach, 2015-11-18)
      We prove that every finitely generated solvable minimax group can be realized as a quotient of a torsion-free solvable minimax group. This result has an application to the investigation of random walks on finitely generated ...
    • Totally Acyclic Complexes 

      [OWP-2016-14] Estrada, Sergio; Fu, Xianhui; Iacob, Alina (Mathematisches Forschungsinstitut Oberwolfach, 2016-08-17)
      We prove first (Proposition 3) that, over any ring $R$, an acyclic complex of projective modules is totally acyclic if and only if the cycles of every acyclic complex of Gorenstein projective modules are Gorenstein projective. ...
    • The Tutte Polynomial of Ideal Arrangements 

      [OWP-2018-28] Randriamaro, Hery (Mathematisches Forschungsinstitut Oberwolfach, 2018-12-21)
      The Tutte polynomial is originally a bivariate polynomial enumerating the colorings of a graph and of its dual graph. But it reveals more of the internal structure of the graph like its number of forests, of spanning ...
    • Unconditional Convergence of Spectral Decompositions of 1D Dirac Operators with Regular Boundary Conditions 

      [OWP-2010-21] Djakov, Plamen; Mitjagin, Boris S. (Mathematisches Forschungsinstitut Oberwolfach, 2010-03-19)
    • A Uniform Model for Kirillov-Reshetikhin Crystals I: Lifting the Parabolic Quantum Bruhat Graph 

      [OWP-2012-18] Lenart, Cristian; Naito, Satoshi; Sagaki, Daisuke; Schilling, Anne; Shimozono, Mark (Mathematisches Forschungsinstitut Oberwolfach, 2012)
      We consider two lifts of the parabolic quantum Bruhat graph, one into the Bruhat order in the affine Weyl group and the other into a level-zero weight poset first considered by Littelmann. The lift into the affine Weyl ...
    • Upper bounds for the number of solutions to quartic thue equations 

      [OWP-2011-21] Akhtari, Shabnam (Mathematisches Forschungsinstitut Oberwolfach, 2011)
      We will give upper bounds for the number of integral solutions to quartic Thue equations. Our main tool here is a logarithmic curve $\phi(x,y)$ that allows us to use the theory of linear forms in logarithms. This manuscript ...
    • Upper tails for intersection local times of random walks in supercritical dimensions 

      [OWP-2008-02] Chen, Xia; Mörters, Peter (Mathematisches Forschungsinstitut Oberwolfach, 2008-03-06)
      We determine the precise asymptotics of the logarithmic upper tail probability of the total intersection local time of $p$ independent random walks in $\mathbb{Z}^d$ under the assumption $p(d-2)>d$. Our approach allows a ...
    • Urn Models & Operator Ordering Procedures 

      [OWP-2008-06] Blasiak, Pawel (Mathematisches Forschungsinstitut Oberwolfach, 2008-03-10)
      Ordering of operators is purely combinatorial task involving a number of commutators shuffling components of operator expression to desired form. Here we show how it can be illustrated by simple urn models in which normal ...
    • 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 ...