Harmonic Functions and Potentials on Finite or Infinite Networks Random walks Markov chains and electrical networks serve as an introduction to the study of real valued functions on finite or infinite graphs with appropriate interpretations using probability theory and current voltage laws. The relation between this type of function theory and the (Newton) potential theory on the Euclidean spaces is well established. The latter theory has been variously generalized one example being the axiomatic potential theory on locally compact spaces developed by Brelot with later ramifications from Bauer Constantinescu and Cornea. A network is a graph with edge weights that need not be symmetric. This book presents an autonomous theory of harmonic functions and potentials defined on a finite or infinite network on the lines of axiomatic potential theory. Random walks and electrical networks are important sources for the advancement of the theory. 1 Laplace Operators on Networks and Trees 2 Potential Theory on Finite Networks 3 Harmonic Function Theory on Infinite Networks 4 Schrödinger Operators and Subordinate Structures on Infinite Networks 5 Polyharmonic Functions on Trees.