Projective rigidity of circle packings

Francesco Bonsante (U Pavia)

Oct 16. 2023, 09:30 — 10:20

Observing that the notion of disk in CP^1 is invariant under projective transformations, Kojima, Mizushima and Tan proposed the study of circle packings on surfaces equipped with  complex projective structure. The main observation is that  combinatorially  a circle packing is described by a triangulation of the surface, called the nerve of the circle packing. In the talk we will prove that for a fixed surface S of genus g bigger than one, and for a fixed triangulation T on S,  the moduli space of pairs (P,C), where P is a complex projective structure S and C is a circle packing with nerve equal to T, is naturally a manifold of dimension 6g-6. We moreover prove that the circle packing is locally rigid, in the sense that there is no local deformation of C within the projective surface P. 

Results presented in the talk are part of a  collaboration with Michael Wolf.

Further Information
Venue:
ESI Boltzmann Lecture Hall
Associated Event:
Geometry beyond Riemann: Curvature and Rigidity (Thematic Programme)
Organizer(s):
Ivan Izmestiev (TU Vienna)
Athanase Papadopoulos (IRMA, Strasbourg)
Marc Troyanov (EPFL, Lausanne)
Sumio Yamada (Gakushuin U, Tokyo)