Title: Indefinite boundary value problems on graphs,
Abstract: We consider the spectral structure of indefinite second order boundary-value
problems on graphs. A variational formulation for such boundary-value problems
on graphs is given and we obtain both full and half-range completeness results.
This leads to a max-min principle and as a consequence we can formulate an
analogue of Dirichlet-Neumann bracketing and this in turn gives rise to
asymptotic approximations for the eigenvalues.