• On Concentrators and Related Approximation Constants 

      [OWP-2013-14] Bondarenko, A. V.; Prymak, A.; Radchenko, D. (Mathematisches Forschungsinstitut Oberwolfach, 2013-06-10)
      Pippenger ([Pip77]) showed the existence of (6m, 4m, 3m, 6)-concentrator for each positive integer m using a probabilistic method. We generalize his approach and prove existence of (6m, 4m, 3m, 5.05)-concentrator (which ...
    • On conjugacy of MASAs and the outer automorphism group of the Cuntz algebra 

      [OWP-2013-21] Conti, Roberto; Hong, Jeong Hee; Szymański, Wojciech (Mathematisches Forschungsinstitut Oberwolfach, 2013-10-29)
      We investigate the structure of the outer automorphism group of the Cuntz algebra and the closely related problem of conjugacy of MASAa in $\mathcal{O}_n$. In particular, we exhibit an uncountable family of MASAs, conjugate ...
    • Solid extensions of the Cesàro operator on the Hardy space H2(D) 

      [OWP-2013-11] Curbera, Guillermo P.; Ricker, Werner J. (Mathematisches Forschungsinstitut Oberwolfach, 2013-04-23)
      We introduce and study the largest Banach space of analytic functions on the unit disc which is solid for the coefficient-wise order and to which the classical Ces`aro operator $\mathcal{C}:H^2 \to H^2$ can be continuously ...