Abstract graph-like space and vector-valued metric graphs
  In this note we present some abstract ideas how one can construct spaces from building blocks according to a graph. The coupling is expressed via boundary pairs, and can be applied to very different spaces such as discrete graphs, quantum graphs or graph-like manifolds. We show a spectral analysis of graph-like spaces, and consider as a special case vector-valued quantum graphs. Moreover, we provide a prototype of a convergence theorem for shrinking graph-like spaces with Dirichlet boundary conditions. (Dedicated to Pavel Exner's 70th birthday) 
Olaf Post
math.SP math-ph math.CO math.FA math.MP