A smooth flat Riemannian
manifold is called an exceptional domain if it admits positive harmonic functions
having vanishing Dirichlet boundary data and constant (nonzero) Neumann
boundary data. In analogy with minimal surfaces, a representation formula is derived
and applied to the classification of exceptional domains. Some interesting open
problems are proposed along the way.
Université Paris Diderot–Paris
7
Institut de Mathématiques de Jussieu, UMR CNRS 7586
UFR de Mathématiques, Case 7012
Bâtiment Chevaleret
75205 Paris Cedex 13
France