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The extremal length systole of the cube punctured at its vertices

Samuel Dobchies and Maxime Fortier Bourque

Vol. 345 (2026), No. 1, 45–84
Abstract

We prove that the extremal length systole of the cube punctured at its vertices is realized by the twelve curves surrounding its edges and give a characterization of the corresponding quadratic differentials, allowing us to estimate its value to high precision. The proof uses a mixture of exact calculations done using branched covers and elliptic integrals, together with estimates obtained using either the geometry of geodesic trajectories on the cube or explicit conformal maps.

Keywords
extremal length, systole, punctured sphere
Mathematical Subject Classification
Primary: 30F30, 30F45, 31A15
Milestones
Received: 4 June 2024
Revised: 17 April 2026
Accepted: 9 July 2026
Published: 25 September 2026
Authors
Samuel Dobchies
Département de mathématiques
Université de Sherbrooke
Sherbrooke
Canada
Maxime Fortier Bourque
Département de mathématiques et de statistique
Université de Montréal
Montréal
Canada

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