1-harmonic functions on a network

A minimizer of the Dirichlet norm of order 1 is called a 1-harmonic function. The aim of this paper is a research of properties of 1-harmonic functions on a network. First we consider the 1-Dirichlet space and show that every network is of 1-hyperbolic type and that the ideal boundary coincides with the 1-harmonic boundary. Next we introduce the notion of 1-harmonic functions and that of strongly 1-harmonic functions. We discuss the Dirichlet problem and the maximum principle with respect to (strongly) 1-harmonic functions.