International Workshop

Invariant Distances and Metrics in Complex Analysis

in honour of our teacher and friend Prof. Dr. Peter Pflug on the occasion of his 80th birthday

July 11 – 15, 2023,
Sofia, Bulgaria

in the frame of the International Conference “Mathematics Days in Sofia”

T

he workshop will bring together researchers around a central theme of the geometric properties of various distances and metric of domains in Cn (squeezing function, Gromov hyperbolicity, visibility of geodesics) as well as related subjects.

Organizing Committee

  • Nikolai Nikolov (Institute of Mathematics and Informatics, Bulgaria)
  • Pascal J. Thomas (Université Paul Sabatier, France)
  • Krassimira Ivanova (Institute of Mathematics and Informatics, Bulgaria) – scientific secretary

Speakers

  • Ahmed Yekta Ökten, Université Paul Sabatier, France (PhD student)

  • Anand Chavan, Jagiellonian University, Poland (PhD student)

  • Andrew Zimmer, University of Wisconsin-Madison, USA

  • Armen Edigarian, Jagiellonian University, Poland

  • Filippo Bracci, Università di Roma “Tor Vergata”, Italy

  • Gautam Bharali, Indian Institute of Science, India

  • Hervé Gaussier, Université Grenoble 1, France

  • Łukasz Kosinski, Jagiellonian University, Poland

  • Matteo Fiacchi, University of Ljubljana, Slovenia

  • Sławomir Dinew, Jagiellonian University, Poland

  • Włodzimierz Zwonek, Jagiellonian University, Poland
  • Zywomir Dinew, Jagiellonian University, Poland

Program and Abstracts

Hall 503, Institute of Mathematics and Informatics

12th July (Wednesday)
Chair: Gautam Bharali
14:00 Filippo Bracci: Visibility and geodesic loops in Kobayashi complete hyperbolic and Gromov hyperbolic domains
14:45 Matteo Fiacchi: The Julia-Wolff-Carathéodory theorem in convex domains of finite type
15:30 Coffee Break
Chair: Filippo Bracci
16:00 Gautam Bharali: The squeezing function: exact computations and a new application
16:45 Armen Edigarian: Isometries on the symmetrized bidisc
13th July (Thursday)
Chair: Armen Edigarian
14:00 Włodzimierz Zwonek: 2-proper holomorphic images of the Cartan domains
14:45 Łukasz Kosinski: Extension property
15:30 Coffee Break
Chair: Wlodzimierz Zwonek
16:00 Sławomir Dinew: Complex nonlinear equations, weak solutions and admissible domains
16:45 Zywomir Dinew: Aspects of B-regularity
14th July (Friday)
Chair: Pascal J. Thomas
14:00 Herve Gaussier: Invariant metrics – old and more recent results
14:45 Ahmed Yekta Ökten: Estimates of the Kobayashi distance of strongly pseudoconvex domains
15:30 Coffee Break
Chair: Herve Gaussier
16:00 Andrew Zimmer: Bounded geometry in several complex variables
16:45 Open problems
  • Ahmed Yekta Ökten

    Estimates of the Kobayashi distance of strongly pseudoconvex domains

    We will present sharp upper and lower bounds (of the same type) for the Kobyashi distance of a C2,α-smooth strongly pseudoconvex domain. These bounds come from the study of the behaviour of complex geodesics and extend the well-known Balogh-Bonk estimate (2000). The talk is based on a joint work with L. Kosinski and N. Nikolov.

    Presentation

  • Andrew Zimmer

    Bounded geometry in several complex variables

    I will discuss several different bounded geometry conditions for a complex manifold. Then describe some applications.

    Presentation

  • Armen Edigarian

    Isometries on the symmetrized bidisc

    We study Caratheodory isometries in the symmetrized bidisc. We show that any C1-isometry is holomorphic or anti-holomorphic. By-pass we give also a new proof of the description of automorphisms of the symmetrized bidisc, using „only” formulas for the distance and infinitesimal metric, but not using W. Kaup’s result on the orbit of the origin under automorphisms (as it was done by Jarnicki-Pflug).

  • Filippo Bracci

    Visibility and geodesic loops in Kobayashi complete hyperbolic and Gromov hyperbolic domains

    In this talk I will summarise the recent results (and open questions) about visibility and geodesic loops in bounded domains of the complex space which are both complete Kobayashi hyperbolic and Gromov hyperbolic. In particular, I will give a characterization of visibility and the existence of geodesic loops in terms of “geodesic frames” and show some applications.

    Presentation

  • Gautam Bharali

    The squeezing function: exact computations and a new application

    In recent years, work on the squeezing function has focused largely on a diagnostic for detecting (local) strong Levi pseudoconvexity. Comparatively less attention has been focused on what the squeezing function can say about the complex geometry of a domain and on the very amusing — but rather hard — problem of computing the squeezing function exactly. In this talk, we shall revisit the latter aspects of the squeezing function. This examination of the squeezing function will rely on an old idea, suitably adapted, of “fitting” large polydiscs into domains, which has been useful in the past in the non-strongly pseudoconvex context. The talk is based on a joint work with Diganta Borah and Sushil Gorai.

    Presentation

  • Herve Gaussier

    Invariant metrics – old and more recent results

    Invariant metrics under the action of biholomorphisms, such as the Kobayashi and Carathéodory metrics, or the Bergman and Kähler-Einstein metrics, are important metrics that can encode certain properties of the complex manifolds on which they are defined. In this talk, I will address some problems concerning their study. I will present some classical results establishing links between the geometric properties of complex manifolds and the properties of their invariant metrics. I will also present more recent studies in this direction.

    Presentation

  • Łukasz Kosinski

    Extension property

    We study sets in convex domains that have the polynomial extension property.

  • Matteo Fiacchi

    The Julia-Wolff-Carathéodory theorem in convex domains of finite type

    The classical Julia-Wolff-Carathéodory theorem says that, if f is a holomorphic self-map of the unit disk D and ξ∈∂D such that liminfz→ξ(1−|f(z)|)/(1−|z|)<∞ then the derivative f′ has non-tangential limit at ξ and the limit value can be computed in terms of the Poincaré distance. The theorem has been generalized to several complex variables by Rudin in the unit ball, by Abate in strongly convex and by Abate-Tauraso in convex domains of finite type, under some technical assumptions. In this talk I will present a version of the Julia-Wolff-Carathéodory theorem in convex domains of finite type in full generality, using metric geometry techniques.
    This is a joint work with L. Arosio.

    Presentation

  • Sławomir Dinew

    Complex nonlinear equations, weak solutions and admissible domains

    We report on recent progress in the study of nonlinear elliptic equations in domains in Cn. Existence of weak solutions to those, if suitable boundary behavior is assumed, forces geometric properties of the domain.

  • Włodzimierz Zwonek

    2-proper holomorphic images of the Cartan domains

    The ideas that generalize the construction of the symmetrized bidisc and the tetrablock as 2-proper holomorphic images of the Cartan domains will be presented. The new domains have many geometric properties that will be presented in the lecture. That will contain description of automorphisms, properties of the Bergman kernel, (non)-convexity of the domains. The talk is based on the common research with Gargi Ghosh.

    Presentation

  • Zywomir Dinew

    Aspects of B-regularity

    The notion of B-regularity was introduced by Sibony in his famous Duke paper from 1987. For compact sets it means that one can approximate uniformly an arbitrary continuous function by continuous plurisubharmonic functions defined on (varying) neighborhoods. We will present some new properties of B-regular compacts and domains and provide some examples. This is an ongoing research with Slawomir Dinew.

    Presentation

Venue and General Information

The workshop will be held at Institute of Mathematics and Informatics at the Bulgarian Academy of Sciences (Sofia, Acad. Georgi Bonchev Str., Block 8), Hall 503.

Arrival day: 11th of July, Departure day: 15th of July.

The Event is Supported by: