Browsing 2010 by Issue Date
Now showing items 120 of 22

There is a unique real tight contact 3ball
[OWP201001] (Mathematisches Forschungsinstitut Oberwolfach, 2010)We prove that there is a unique real tight contact structure on the 3ball with convex boundary up to isotopy through real tight contact structures. We also give a partial classification of the real tight solid tori with ... 
Supertropical linear algebra
[OWP201014] (Mathematisches Forschungsinstitut Oberwolfach, 2010)The objective of this paper is to lay out the algebraic theory of supertropical vector spaces and linear algebra, utilizing the key antisymmetric relation of "ghost surpasses." Special attention is paid to the various ... 
Supertropical semirings and supervaluations
[OWP201005] (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 maxplus setting), and then define a supervaluation $\varphi$ as a suitable map into ... 
A series of algebras generalizing the Octonions and HurwitzRadon Identity
[OWP201010] (Mathematisches Forschungsinstitut Oberwolfach, 2010)We study nonassociative twisted group algebras over $(\mathbb{Z}_2)^n$ with cubic twisting functions. We construct a series of algebras that extend the classical algebra of octonions in the same way as the Clifford algebras ... 
On the complement of the dense orbit for a quiver of type A
[OWP201011] (Mathematisches Forschungsinstitut Oberwolfach, 2010)Let $\mathbb{A}_t$ be the directed quiver of type $A$ with $t$ vertices. For each dimension vector $d$ there is a dense orbit in the corresponding representation space. The principal aim of this note is to use just rank ... 
Supertropical Matrix Algebra III : Powers of Matrices and Generalized Eigenspaces
[OWP201020] (Mathematisches Forschungsinstitut Oberwolfach, 2010)We investigate powers of supertropical matrices, with special attention to the role of the coefficients of the supertropical characteristic polynomial (especially the supertropical trace) in controlling the rank of a power ... 
A construction of hyperbolic Coxeter groups
[OWP201004] (Mathematisches Forschungsinstitut Oberwolfach, 2010)We give a simple construction of Gromov hyperbolic Coxeter groups of arbitrarily large virtual cohomological dimension. Our construction provides new examples of such groups. Using this one can construct e.g. new groups ... 
Nonintegrated defect relation for meromorphic maps of complete Kähler manifolds into a projective variety intersecting hypersurfaces
[OWP201019] (Mathematisches Forschungsinstitut Oberwolfach, 2010)In 1985, Fujimoto established a nonintegrated defect relation for meromorphic maps of complete Kähler manifolds into the complex projective space intersecting hyperplanes in general position. In this paper, we generalize ... 
Weakduality based adaptive finite element methods for PDEconstrained optimization with pointwise gradient stateconstraints
[OWP201015] (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. ... 
On Generalizations of KacMoody Groups
[OWP201006] (Mathematisches Forschungsinstitut Oberwolfach, 20100310)In [7] we define a CurtisTits group as a certain generalization of a KacMoody group. We distinguish between orientable and nonorientable CurtisTits groups and identify all orientable CurtisTits groups as KacMoody ... 
Representation Theory of NonCommutative Association Schemes of Order
[OWP201007] (Mathematisches Forschungsinstitut Oberwolfach, 20100311)In this note, we investigate association schemes of order 6. We prove that nonnormal closed subsets of such schemes have order 2 and that normal closed subsets of noncommutative schemes have order 2 or 3. After that, ... 
Spectral Sequences in Combinatorial Geometry: Cheeses, Inscribed Sets, and BorsukUlam Type Theorems
[OWP201008] (Mathematisches Forschungsinstitut Oberwolfach, 20100312)Algebraic topological methods are especially suited to determining the nonexistence of continuous mappings satisfying certain properties. In combinatorial problems it is sometimes possible to define a mapping from a space ... 
On the Complement of the Richardson Orbit
[OWP201009] (Mathematisches Forschungsinstitut Oberwolfach, 20100313)We consider parabolic subgroups of a general algebraic group over an algebraically closed field $k$ whose Levi part has exactly $t$ factors. By a classical theorem of Richardson, the nilradical of a parabolic subgroup $P$ ... 
Plethysms, replicated Schur functions and series, with applications to vertex operators
[OWP201012] (Mathematisches Forschungsinstitut Oberwolfach, 20100314)Specializations of Schur functions are exploited to define and evaluate the Schur functions $s_\lambda [\alpha X]$ and plethysms $s_\lambda [\alpha s_\nu(X))]$ for any $\alpha$integer, real or complex. Plethysms are then ... 
Locally conformally Kähler manifolds admitting a holomorphic conformal flow
[OWP201013] (Mathematisches Forschungsinstitut Oberwolfach, 20100315)A manifold $M$ is locally conformally Kähler (LCK) if it admits a Kähler covering $\tilde{M}$ with monodromy acting by holomorphic homotheties. Let $M$ be an LCK manifold admitting a holomorphic conformal flow of ... 
Shape Theory and Extensions of C*Algebras
[OWP201016] (Mathematisches Forschungsinstitut Oberwolfach, 20100316)Let A, A' be separable $C^*$algebras, $B$ a stable $\sigma$unital $C^*$algebra. Our main result is the construction of the pairing $[[A', A]] \times Ext^{1/2}(A,B) \to Ext^{1/2}(A',B)$, where $[[A', A]]$ denotes the ... 
SemiInvertible Extensions of C*Algebras
[OWP201017] (Mathematisches Forschungsinstitut Oberwolfach, 20100317)We prolonge the list of $C^*$algebras for which all extensions by any stable separable $C^*$algebra are semiinvertible. In particular, we handle certain amalgamations, both of $C^*$algebras and of groups. Concerning ... 
On Selfinjective Artin Algebras Having Generalized Standard Quasitubes
[OWP201018] (Mathematisches Forschungsinstitut Oberwolfach, 20100318)We give a complete description of the Morita equivalence classes of all connected selfinjective artin algebras for which the AuslanderReiten quiver admits a family of quasitubes having common composition factors, closed ... 
Unconditional Convergence of Spectral Decompositions of 1D Dirac Operators with Regular Boundary Conditions
[OWP201021] (Mathematisches Forschungsinstitut Oberwolfach, 20100319) 
Stochastic mean payoff game: smoothed analysis and approximation schemes
[OWP201022] (Mathematisches Forschungsinstitut Oberwolfach, 20100320)We consider twoperson zerosum stochastic mean payoff games with perfect information modeled by a digraph with black, white, and random vertices. These BWRgames games are polynomially equivalent with the classical Gillette ...