• 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 ...
    • Averages of Shifted Convolutions of d3(n) 

      [OWP-2011-11] Baier, Stephan; Browning, Tim; Marasingha, Gihan; Zhao, Liangyi (Mathematisches Forschungsinstitut Oberwolfach, 2011-05-13)
      We investigate the first and second moments of shifted convolutions of the generalised divisor function $d_3(n)$.
    • Asymptotic behavior of the eigenvalues and eigenfunctions to a spectral problem in thick cascade junction with concentrated masses 

      [OWP-2011-12] Chechkin, Gregory A.; Mel'nyk, Taras A. (Mathematisches Forschungsinstitut Oberwolfach, 2011-05-14)
      The asymptotic behavior (as $\varepsilon \to 0$) of eigenvalues and eigenfunctions of a boundaryvalue problem for the Laplace operator in a thick cascade junction with concentrated masses is investigated. This cascade ...
    • Definable orthogonality classes in accessible categories are small 

      [OWP-2011-14] Bagaria, Joan; Casacuberta, Carles; Mathias, Adrian R. D.; Rosický, Jiří (Mathematisches Forschungsinstitut Oberwolfach, 2011-05-15)
      We lower substantially the strength of the assumptions needed for the validity of certain results in category theory and homotopy theory which were known to follow from Vopenka's principle. We prove that the necessary ...
    • Formal adjoints of linear DAE operators and their role in optimal control 

      [OWP-2011-15] Kunkel, Peter; Mehrmann, Volker (Mathematisches Forschungsinstitut Oberwolfach, 2011-05-16)
      For regular strangeness-free linear differential-algebraic equations (DAEs) the definition of an adjoint DAE is straightforward. This definition can be formally extended to general linear DAEs. In this paper, we analyze ...
    • An inductive approach to coxeter arrangements and solomon's descent algebra 

      [OWP-2011-16] Douglass, J. Matthew; Pfeiffer, Götz; Röhrle, Gerhard (Mathematisches Forschungsinstitut Oberwolfach, 2011-05-17)
      In our recent paper [3], we claimed that both the group algebra of a finite Coxeter group W as well as the Orlik-Solomon algebra of W can be decomposed into a sum of induced one-dimensional representations of centralizers, ...
    • A categorical model for the virtual braid group 

      [OWP-2011-19] Kauffman, Louis H.; Lambropoulou, Sofia (Mathematisches Forschungsinstitut Oberwolfach, 2011-05-18)
    • Braid equivalences and the L-moves 

      [OWP-2011-20] Lambropoulou, Sofia (Mathematisches Forschungsinstitut Oberwolfach, 2011-05-19)
      In this survey paper we present the L-moves between braids and how they can adapt and serve for establishing and proving braid equivalence theorems for various diagrammatic settings, such as for classical knots, for knots ...
    • 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 ...
    • A note on delta hedging in markets with jumps 

      [OWP-2011-23] Mijatović, Aleksandar; Urusov, Mikhail A. (Mathematisches Forschungsinstitut Oberwolfach, 2011-05-21)
      Modelling stock prices via jump processes is common in financial markets. In practice, to hedge a contingent claim one typically uses the so-called delta-hedging strategy. This strategy stems from the Black–Merton–Scholes ...
    • Extremal configurations of polygonal linkages 

      [OWP-2011-24] Khimshiashvili, Giorgi; Panina, Gaiane; Siersma, Dirk; Zhukova, Alena (Mathematisches Forschungsinstitut Oberwolfach, 2011-05-22)
    • Crystal energy functions via the charge in types A and C 

      [OWP-2011-25] Lenart, Cristian; Schilling, Anne (Mathematisches Forschungsinstitut Oberwolfach, 2011-05-23)
      The Ram-Yip formula for Macdonald polynomials (at $t=0$) provides a statistic which we call charge. In types $A$ and $C$ it can be defined on tensor products of Kashiwara-Nakashima single column crystals. In this ...
    • Self-adjoint differential-algebraic equations 

      [OWP-2011-27] Kunkel, Peter; Mehrmann, Volker; Scholz, Lena (Mathematisches Forschungsinstitut Oberwolfach, 2011-05-24)
      Motivated from linear-quadratic optimal control problems for differential-algebraic equations (DAEs), we study the functional analytic properties of the operator associated with the necessary optimality boundary value ...
    • Infeasibility certificates for linear matrix inequalities 

      [OWP-2011-28] Klep, Igor; Schweighofer, Markus (Mathematisches Forschungsinstitut Oberwolfach, 2011-05-25)
      Farkas' lemma is a fundamental result from linear programming providing linear certi cates for infeasibility of systems of linear inequalities. In semidefinite programming, such linear certificates only exist for strongly ...
    • Steinberg groups for Jordan pairs 

      [OWP-2011-29] Loos, Ottmar; Neher, Erhard (Mathematisches Forschungsinstitut Oberwolfach, 2011-05-26)
      We introduce categories of groups with commutator relations with respect to root groups and Weyl elements, permuting the root groups. This allows us to view the classical Steinberg groups, for example the Steinberg group ...
    • Algebraic geometric comparison of probability distributions 

      [OWP-2011-30] Király, Franz J.; Bünau, Paul von; Meinecke, Frank C.; Blythe, Duncan A. J.; Müller, Klaus-Robert (Mathematisches Forschungsinstitut Oberwolfach, 2011-05-27)
      We propose a novel algebraic framework for treating probability distributions represented by their cumulants such as the mean and covariance matrix. As an example, we consider the unsupervised learning problem of finding ...
    • The Weyl group of the Cuntz 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 ...
    • On Canonical Forms for Two-person Zero-sum Limit Average Payoff Stochastic Games 

      [OWP-2011-35] Boros, Endre; Elbassioni, Khaled; Gurvich, Vladimir; Makino, Kazuhisa (Mathematisches Forschungsinstitut Oberwolfach, 2011-05-29)
      We consider two-person zero-sum mean payoff undiscounted stochastic games. We give a sufficient condition for the existence of a saddle point in uniformly optimal stationary strategies. Namely, we obtain sufficient ...
    • Quotients of Index Two and General Quotients in a Space of Orderings 

      [OWP-2011-36] Gladki, Pawel; Marshall, Murray (Mathematisches Forschungsinstitut Oberwolfach, 2011-05-30)
      In this paper we investigate quotient structures and quotient spaces of a space of orderings arising from subgroups of index two. We provide necessary and sufficient conditions for a quotient structure to be a quotient ...
    • Coxeter Arrangements and Solomon's Descent Algebra 

      [OWP-2011-03] Douglass, J. Matthew; Pfeiffer, Götz; Röhrle, Gerhard (Mathematisches Forschungsinstitut Oberwolfach, 2011-05-6)