• Representation Theory of Non-Commutative Association Schemes of Order 

      [OWP-2010-07] Hanaki, Akihide; Zieschang, Paul-Hermann (Mathematisches Forschungsinstitut Oberwolfach, 2010-03-11)
      In this note, we investigate association schemes of order 6. We prove that non-normal closed subsets of such schemes have order 2 and that normal closed subsets of non-commutative schemes have order 2 or 3. After that, ...
    • Semi-Invertible Extensions of C*-Algebras 

      [OWP-2010-17] Manujlov, Vladimir M.; Thomsen, Klaus (Mathematisches Forschungsinstitut Oberwolfach, 2010-03-17)
      We prolonge the list of $C^*$-algebras for which all extensions by any stable separable $C^*$-algebra are semi-invertible. In particular, we handle certain amalgamations, both of $C^*$-algebras and of groups. Concerning ...
    • A series of algebras generalizing the Octonions and Hurwitz-Radon Identity 

      [OWP-2010-10] Morier-Genoud, Sophie; Ovsienko, Valentin (Mathematisches Forschungsinstitut Oberwolfach, 2010)
      We study non-associative 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 ...
    • Shape Theory and Extensions of C*-Algebras 

      [OWP-2010-16] Manujlov, Vladimir M.; Thomsen, Klaus (Mathematisches Forschungsinstitut Oberwolfach, 2010-03-16)
      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 ...
    • Spectral Sequences in Combinatorial Geometry: Cheeses, Inscribed Sets, and Borsuk-Ulam Type Theorems 

      [OWP-2010-08] Blagojevic, Pavle V. M.; Blagojevic, Aleksandra; Dimitrijevic McCleary, John (Mathematisches Forschungsinstitut Oberwolfach, 2010-03-12)
      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 ...
    • Stochastic mean payoff game: smoothed analysis and approximation schemes 

      [OWP-2010-22] Boros, Endre; Elbassioni, Khaled; Fouz, Mahmoud; Gurvich, Vladimir; Manthey, Bodo (Mathematisches Forschungsinstitut Oberwolfach, 2010-03-20)
      We consider two-person zero-sum stochastic mean payoff games with perfect information modeled by a digraph with black, white, and random vertices. These BWR-games games are polynomially equivalent with the classical Gillette ...
    • Supertropical linear algebra 

      [OWP-2010-14] Izhakian, Zur; Knebusch, Manfred; Rowen, Louis (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 Matrix Algebra III : Powers of Matrices and Generalized Eigenspaces 

      [OWP-2010-20] Izhakian, Zur; Rowen, Louis (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 ...
    • 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 ...
    • 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 ...
    • 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)
    • Weak-duality based adaptive finite element methods for PDE-constrained optimization with pointwise gradient state-constraints 

      [OWP-2010-15] Hintermüller, Michael; Hinze, Michael; Hoppe, Ronald H. W. (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. ...