An optimal irrigation network with infinitely many branching points

¹ Max-Planck-Institut für Mathematik in den Naturwissenschaften, Inselstraße 22, 04103 Leipzig, Germany
marchese@mis.mpg.de
² Institut für Mathematik, Universität Zürich, Winterthurerstrasse 190, 8057 Zürich, Switzerland
annalisa.massaccesi@math.uzh.ch

Received: 24 November 2014

Abstract

The Gilbert−Steiner problem is a mass transportation problem, where the cost of the transportation depends on the network used to move the mass and it is proportional to a certain power of the “flow”. In this paper, we introduce a new formulation of the problem, which turns it into the minimization of a convex functional in a class of currents with coefficients in a group. This framework allows us to define calibrations. We apply this technique to prove the optimality of a certain irrigation network in the separable Hilbert space ℓ², having countably many branching points and a continuous amount of endpoints.