On the spectral theory of 1D Schrödinger and Dirac operators with point interactions and quantum graphs.

We will consider certain spectral properties of three classical operators:
1. one dimensional Schrödinger operators with point interactions;
2. 1D Dirac operators with point interactions;
3. quantum graphs.
A connection of two first classes of operators with certain classes of Jacobi matrices will be discussed.
A connection of quantum graphs with discrete graphs will be discussed too.