Multi angle

H 1 The story of Kalton's last unpublished paper

Auteurs : Castillo, Jesús M.F. (Auteur de la Conférence)
CIRM (Editeur )

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    Résumé : I'd like to share with the audience the Kaltonian story behind [1], started in 2004, including the problems we wanted to solve, and could not.
    In that paper we show that Rochberg's generalized interpolation spaces $\mathbb{Z}^{(n)}$ [5] can be arranged to form exact sequences $0\to\mathbb{Z}^{(n)}\to\mathbb{Z}^{(n+k)}\to\mathbb{Z}^{(k)} \to 0$. In the particular case of Hilbert spaces obtained from the interpolation scale of $\ell_p$ spaces then $\mathbb{Z}^{(2)}$ becomes the well-known Kalton-Peck $Z_2$ space, and one gets from here that there are quite natural nontrivial twisted sums $0\to Z_2\to\mathbb{Z}^{(4)}\to Z_2 \to0$ of $Z_2$ with itself. The twisted sum space $\mathbb{Z}^{(4)}$ does not embeds in, or is a quotient of, a twisted Hilbert space and does not contain $\ell_2$ complemented. We will also construct another nontrivial twisted sum of $Z_2$ with itself that contains $\ell_2$ complemented. These results have some connection with the nowadays called Kalton calculus [3, 4], and thus several recent advances [2] in this theory that combines twisted sums and interpolation theory will be shown.

    Banach space - twisted sum - complex interpolation - Hilbert space

    Codes MSC :
    46B20 - Geometry and structure of normed linear spaces
    46B70 - Interpolation between normed linear spaces
    46M18 - Homological methods

      Informations sur la Vidéo

      Langue : Anglais
      Date de publication : 21/01/15
      Date de captation : 14/01/15
      Collection : Research talks ; Analysis and its Applications
      Format : quicktime ; audio/x-aac
      Durée : 00:46:27
      Domaine : Analysis and its Applications
      Audience : Chercheurs ; Doctorants , Post - Doctorants
      Download : https://videos.cirm-math.fr/2015-01-14_Castillo.mp4

    Informations sur la rencontre

    Nom de la rencontre : Banach spaces and their applications in analysis / Espaces de Banach et applications à l'analyse
    Organisateurs de la rencontre : Albiac, Fernando ; Casazza, Peter G. ; Godefroy, Gilles
    Dates : 12/01/15 - 16/01/15
    Année de la rencontre : 2015

    Citation Data

    DOI : 10.24350/CIRM.V.18666103
    Cite this video as: Castillo, Jesús M.F. (2015). The story of Kalton's last unpublished paper. CIRM. Audiovisual resource. doi:10.24350/CIRM.V.18666103
    URI : http://dx.doi.org/10.24350/CIRM.V.18666103


    1. [1] Cabello, F., Castillo, J.M.F., & Kalton, N.J. (2014). Complex interpolation and twisted twisted Hilbert spaces. - http://arxiv.org/abs/1406.6723v1

    2. [2] Castillo, J.M.F., Ferenczi, V., & Gonzalez, M. (2014). Singular twisted sums generated by complex interpolation. - http://arxiv.org/abs/1410.5505v1

    3. [3] Kalton, N.J. (1988). Nonlinear commutators in interpolation theory. Memoirs of the American Mathematical Society, 385, 85 p. - https://zbmath.org/?q=an:0658.46059

    4. [4] Kalton, N.J. (1992). Differentials of complex interpolation processes for Köthe function spaces. Transactions of the American Mathematical Society, 333(2), 479-529 - http://dx.doi.org/10.1090/s0002-9947-1992-1081938-1

    5. [5] Rochberg, R. (1996). Higher order estimates in complex interpolation theory. Pacific Journal of Mathematics, 174(1), 247-267 - https://www.zbmath.org/?q=an:0866.46047

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