• Alternative iterative methods for nonexpansive mappings, rates of convergence and applications 

      [OWP-2009-19] Colao, Vittorio; Leuştean, Laurenţiu; López, Genaro; Martín Márquez, Victoria (Mathematisches Forschungsinstitut Oberwolfach, 2009)
      Alternative iterative methods for a nonexpansive mapping in a Banach space are proposed and proved to be convergent to a common solution to a fixed point problem and a variational inequality. We give rates of asymptotic ...
    • Categorical Linearly Ordered Structures 

      [OWP-2018-08] Downey, Rod; Melnikov, Alexander; Ng, Keng Meng (Mathematisches Forschungsinstitut Oberwolfach, 2018-04-26)
      We prove that for every computable limit ordinal $\alpha$ there exists a computable linear ordering $\mathcal{A}$ which is $\Delta^0_\alpha$-categorical and $\alpha$ is smallest such, but nonetheless for every isomorphic ...
    • Cocycle Superrigidity and Group Actions on Stably Finite C*-Algebras 

      [OWP-2017-01] Gardella, Eusebio; Lupini, Martino (Mathematisches Forschungsinstitut Oberwolfach, 2017-01-17)
      Let $\Lambda $ be a countably infinite property (T) group, and let $D$ be UHF-algebra of infinite type. We prove that there exists a continuum of pairwise non (weakly) cocycle conjugate, strongly outer actions of $\Lambda ...
    • 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 ...
    • Dominance and Transmissions in Supertropical Valuation Theory 

      [OWP-2011-07] Izhakian, Zur; Knebusch, Manfred; Rowen, Louis (Mathematisches Forschungsinstitut Oberwolfach, 2011)
      This paper is a sequel of [IKR1], where we defined supervaluations on a commutative ring $R$ and studied a dominance relation $\Phi >= v$ between supervaluations $\varphi$ and $\upsilon$ on $R$, aiming at an enrichment of ...
    • Monoid valuations and value ordered supervaluations 

      [OWP-2011-17] Izhakian, Zur; Knebusch, Manfred; Rowen, Louis (Mathematisches Forschungsinstitut Oberwolfach, 2011)
      We complement two papers on supertropical valuation theory ([IKR1], [IKR2]) by providing natural examples of m-valuations (= monoid valuations), after that of supervaluations and transmissions between them. The supervaluations ...
    • New representations of matroids and generalizations 

      [OWP-2011-18] Izhakian, Zur; Rhodes, John L. (Mathematisches Forschungsinstitut Oberwolfach, 2011)
      We extend the notion of matroid representations by matrices over fields by considering new representations of matroids by matrices over finite semirings, more precisely over the boolean and the superboolean semirings. This ...
    • 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 ...