Functions in Hardy spaces on multiply-connected domains in the plane are given an explicit characterization in terms of a boundary condition inspired by the two-dimensional Ising model. The key underlying property is the positivity of a certain operator constructed inductively on the number of components of the boundary.
Joachim Stubbe, Luigi Provenzano, Paolo Luzzini, Davide Buoso
Annalisa Buffa, Pablo Antolin Sanchez, Giuliano Guarino