Local control and estimation performance in dynamical networks: Structural and graph-theoretic results

This work examines metrics for target reachability and source observability in dynamical networks, which are especially relevant in a network security context. Specifically, the energy required to control a target node in a network from a remote input is characterized, and dually the fidelity with which a source state can be estimated from a remote measurement is studied. The work highlights an essential asymmetry between the problems: We show that target reachability is often easy, while source observability is almost always impossible. Several spectral and graph-theoretic results are also presented, which give structural insight into how easy or hard target control and source estimation are.