• A Pseudo-Polynomial Algorithm for Mean Payoff Stochastic Games with Perfect Information and Few Random Positions 

      [OWP-2015-20] Boros, Endre; Elbassioni, Khaled; Gurvich, Vladimir; Makino, Kazuhisa (Mathematisches Forschungsinstitut Oberwolfach, 2015)
      We consider two-person zero-sum stochastic mean payoff games with perfect information, or BWR-games, given by a digraph $G = (V,E)$, with local rewards $r : E \to \mathbb{Z}$, and three types of positions: black $V_B$, ...
    • A potential reduction algorithm for two-person zero-sum mean payoff stochastic games 

      [OWP-2015-19] Boros, Endre; Elbassioni, Khaled; Gurvich, Vladimir; Makino, Kazuhisa (Mathematisches Forschungsinstitut Oberwolfach, 2015)
      We suggest a new algorithm for two-person zero-sum undiscounted stochastic games focusing on stationary strategies. Given a positive real $\epsilon$, let us call a stochastic game $\epsilon$-ergodic, if its values from any ...
    • Simulation of Multibody Systems with Servo Constraints through Optimal Control 

      [OWP-2015-18] Altmann, Robert; Heiland, Jan (Mathematisches Forschungsinstitut Oberwolfach, 2015)
      We consider mechanical systems where the dynamics are partially constrained to prescribed trajectories. An example for such a system is a building crane with a load and the requirement that the load moves on a certain path. ...
    • Milnor fibre homology via deformation 

      [OWP-2015-22] Siersma, Dirk; Tibăr, Mihai-Marius (Mathematisches Forschungsinstitut Oberwolfach, 2015)
      In case of one-dimensional singular locus, we use deformations in order toget refined information about the Betti numbers of the Milnor fibre.
    • A nested family of k-total effective rewards for positional games 

      [OWP-2015-21] Boros, Endre; Elbassioni, Khaled; Gurvich, Vladimir; Makino, Kazuhisa (Mathematisches Forschungsinstitut Oberwolfach, 2015)
      We consider Gillette's two-person zero-sum stochastic games with perfect information. For each $k \in \mathbb{Z}_+$ we introduce an effective reward function, called $k$-total. For $k = 0$ and $1$ this function is known ...
    • Composition of Irreducible Morphisms in Quasi-Tubes 

      [OWP-2015-03] Chaio, Claudia; Malicki, Piotr (Mathematisches Forschungsinstitut Oberwolfach, 2015-04-09)
      We study the composition of irreducible morphisms between indecomposable modules lying in quasi-tubes of the Auslander-Reiten quivers of artin algebras $A$ in relation with the powers of the radical of their module category ...
    • Realizing Spaces as Classifying Spaces 

      [OWP-2015-01] Lupton, Gregory; Smith, Samuel Bruce (Mathematisches Forschungsinstitut Oberwolfach, 2015-04-10)
      Which spaces occur as a classifying space for fibrations with a given fibre? We address this question in the context of rational homotopy theory. We construct an infinite family of finite complexes realized (up to rational ...
    • 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 ...
    • Maximal Cohen-Macaulay modules over non-isolated surface singularities and matrix problems 

      [OWP-2015-06] Burban, Igor; Drozd, Yuriy (Mathematisches Forschungsinstitut Oberwolfach, 2015-05-13)
      In this article we develop a new method to deal with maximal Cohen-Macaulay modules over non-isolated surface singularities. In particular, we give a negative answer on an old question of Schreyer about surface singularities ...
    • Gibbs measures associated to the integrals of motion of the periodic derivative nonlinear Schrödinger equation 

      [OWP-2015-04] Genovese, Giuseppe; Lucatti, Renato; Valeri, Daniele (Mathematisches Forschungsinstitut Oberwolfach, 2015-05-18)
      We study the one dimensional periodic derivative nonlinear Schrödinger (DNLS) equation. This is known to be a completely integrable system, in the sense that there is an infinite sequence of formal integrals of motion $\int ...
    • Discrete Translates in Lp (R) 

      [OWP-2015-09] Olevskij, Aleksandr M.; Ulanovskii, Alexander (Mathematisches Forschungsinstitut Oberwolfach, 2015-06-18)
      A set $\Lambda$ is called $p$-spectral if there is a function $g \in L^p (\mathbb{R})$ such that all $\Lambda$-translates $\{g(t-\lambda),\lambda \in \Lambda\}$ span $L^p(\mathbb{R})$. We prove that exponentially small ...
    • 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 ...
    • 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 ...
    • The algebra of differential operators for a Gegenbauer weight matrix 

      [OWP-2015-07] Ignacio Nahuel Zurrián (Mathematisches Forschungsinstitut Oberwolfach, 2015-07-29)
      In this work we study in detail the algebra of differential operators $\mathcal{D}(W)$ associated with a Gegenbauer matrix weight. We prove that two second order operators generate the algebra, indeed $\mathcal{D}(W)$ is ...
    • Instability of point defects in a two-dimensional nematic liquid crystal model 

      [OWP-2015-05] Ignat, Radu; Nguyen, Luc; Slastikov, Valeriy; Zarnescu, Arghir (Mathematisches Forschungsinstitut Oberwolfach, 2015-07-29)
      We study a class of symmetric critical points in a variational 2$D$ Landau - de Gennes model where the state of nematic liquid crystals is described by symmetric traceless $3 \times 3$ matrices. These critical points play ...
    • Hight functions on quaternionic Stiefel manifolds 

      [OWP-2015-10] Macías-Virgós, Enrique; Strom, Jeffrey; Tanré, Daniel; Oprea, John (Mathematisches Forschungsinstitut Oberwolfach, 2015-07-29)
      In this note, we study height functions on quaternionic Stiefel manifolds and prove that all these height functions are Morse-Bott. Among them, we characterize the Morse functions and give a lower bound for their number ...
    • Graphical constructions for the sl(3), C2 and G2 invariants for virtual knots, virtual braids and free knots 

      [OWP-2015-13] Kauffman, Louis H.; Manturov, Vassily Olegovich (Mathematisches Forschungsinstitut Oberwolfach, 2015-07-31)
      We construct graph-valued analogues of the Kuperberg sl(3) and $G_2$ invariants for virtual knots. The restriction of the sl(3) and $G_2$ invariants for classical knots coincides with the usual Homflypt sl(3) invariant and ...
    • Prediction and Quantification of Individual Athletic Performance 

      [OWP-2015-11] Blythe, Duncan A. J.; Király, Franz J. (Mathematisches Forschungsinstitut Oberwolfach, 2015-08-27)
      We present a novel, quantitative view on the human athletic performance of individuals. We obtain a predictor for athletic running performances, a parsimonious model, and a training state summary consisting of three numbers, ...
    • 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 ...
    • Noncommutative Marked Surfaces 

      [OWP-2015-16] Berenstein, Arkady; Retakh, Vladimir (Mathematisches Forschungsinstitut Oberwolfach, 2015-11-18)
      The aim of the paper is to attach a noncommutative cluster-like structure to each marked surface $\Sigma$. This is a noncommutative algebra $\mathcal{A}_\Sigma$ generated by “noncommutative geodesics” between marked points ...