Intrinsic metrics in ring domains
: Rainio Oona
Publisher: Springer International Publishing
: 2022
: Complex Analysis and its Synergies
: Complex Analysis and its Synergies
: 3
: 8
: 1
: 2197-120X
DOI: https://doi.org/10.1007/s40627-022-00092-5
: https://doi.org/10.1007/s40627-022-00092-5
: https://research.utu.fi/converis/portal/detail/Publication/175495372
Three hyperbolic-type metrics including the triangular ratio metric, the j*-metric, and the Möbius metric are studied in an annular ring. The Euclidean midpoint rotation is introduced as a method to create upper and lower bounds for these metrics, and their sharp inequalities are found. A new Möbius-invariant lower bound is proved for the conformal capacity of a general ring domain by using a symmetric quantity defined with the Möbius metric.