Browsing 2011 by Issue Date
Now showing items 2138 of 38

An inductive approach to coxeter arrangements and solomon's descent algebra
[OWP201116] (Mathematisches Forschungsinstitut Oberwolfach, 20110517)In our recent paper [3], we claimed that both the group algebra of a finite Coxeter group W as well as the OrlikSolomon algebra of W can be decomposed into a sum of induced onedimensional representations of centralizers, ... 
A categorical model for the virtual braid group
[OWP201119] (Mathematisches Forschungsinstitut Oberwolfach, 20110518) 
Braid equivalences and the Lmoves
[OWP201120] (Mathematisches Forschungsinstitut Oberwolfach, 20110519)In this survey paper we present the Lmoves 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
[OWP201122] (Mathematisches Forschungsinstitut Oberwolfach, 20110520)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
[OWP201123] (Mathematisches Forschungsinstitut Oberwolfach, 20110521)Modelling stock prices via jump processes is common in financial markets. In practice, to hedge a contingent claim one typically uses the socalled deltahedging strategy. This strategy stems from the Black–Merton–Scholes ... 
Extremal configurations of polygonal linkages
[OWP201124] (Mathematisches Forschungsinstitut Oberwolfach, 20110522) 
Crystal energy functions via the charge in types A and C
[OWP201125] (Mathematisches Forschungsinstitut Oberwolfach, 20110523)The RamYip 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 KashiwaraNakashima single column crystals. In this ... 
Selfadjoint differentialalgebraic equations
[OWP201127] (Mathematisches Forschungsinstitut Oberwolfach, 20110524)Motivated from linearquadratic optimal control problems for differentialalgebraic equations (DAEs), we study the functional analytic properties of the operator associated with the necessary optimality boundary value ... 
Infeasibility certificates for linear matrix inequalities
[OWP201128] (Mathematisches Forschungsinstitut Oberwolfach, 20110525)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
[OWP201129] (Mathematisches Forschungsinstitut Oberwolfach, 20110526)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
[OWP201130] (Mathematisches Forschungsinstitut Oberwolfach, 20110527)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
[OWP201131] (Mathematisches Forschungsinstitut Oberwolfach, 20110528)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 Twoperson Zerosum Limit Average Payoff Stochastic Games
[OWP201135] (Mathematisches Forschungsinstitut Oberwolfach, 20110529)We consider twoperson zerosum 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
[OWP201136] (Mathematisches Forschungsinstitut Oberwolfach, 20110530)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
[OWP201103] (Mathematisches Forschungsinstitut Oberwolfach, 2011056) 
Localized Endomorphisms of Graph Algebras
[OWP201104] (Mathematisches Forschungsinstitut Oberwolfach, 2011057)Endomorphisms of graph $C^*$algebras are investigated. A combinatorial approach to analysis of permutative endomorphisms is developed. Then invertibility criteria for localized endomorphisms are given. Furthermore, ... 
Higher Finiteness Properties of Reductive Arithmetic Groups in Positive Characteristic: the Rank Theorem
[OWP201105] (Mathematisches Forschungsinstitut Oberwolfach, 2011058)We show that the finiteness length of an $S$arithmetic subgroup $\Gamma$ in a noncommutative isotropic absolutely almost simple group $\mathcal{G}$ over a global function field is one less than the sum of the local ranks ... 
On Reflection Subgroups of Finite Coxeter Groups
[OWP201106] (Mathematisches Forschungsinstitut Oberwolfach, 2011059)Let $W$ be a finite Coxeter group. We classify the reflection subgroups of $W$ up to conjugacy and give necessary and sufficient conditions for the map that assigns to a reflection subgroup $R$ of $W$ the conjugacy class ...