Conformal capacity of hedgehogs
: Betsakos Dimitrios, Solynin Alexander, Vuorinen Matti
Publisher: AMER MATHEMATICAL SOC
: 2023
: Conformal Geometry and Dynamics
: CONFORMAL GEOMETRY AND DYNAMICS
: CONFORM GEOM DYN
: 27
: 5
: 55
: 97
: 43
: 1088-4173
DOI: https://doi.org/10.1090/ecgd/381
: https://doi.org/10.1090/ecgd/381
: https://arxiv.org/abs/2205.08107v2
: https://arxiv.org/abs/2205.08107v1
We discuss problems concerning the conformal condenser capacity of “hedgehogs”, which are compact sets E in the unit disk D = {z: |z| < 1} consisting of a central body E0 that is typically a smaller disk Dr = {z: |z| ≤ r}, 0 < r < 1, and several spikes Ek that are compact sets lying on radial intervals I(αk) = {teiαk: 0 ≤ t < 1}. The main questions we are concerned with are the following: (1) How does the conformal capacity cap(E) of (E = ∪nk=0Ek) behave when the spikes Ek, k = 1,…, n, move along the intervals I(αk) toward the central body if their hyperbolic lengths are preserved during the motion? (2) How does the capacity cap(E) depend on the distribution of angles between the spikes Ek? We prove several results related to these questions and discuss methods of applying symmetrization type transformations to study the capacity of hedgehogs. Several open problems, including problems on the capacity of hedgehogs in the three-dimensional hyperbolic space, will also be suggested.