  Controllability is one of the central concepts of modern control theory that
allows a good understanding of a system's behaviour. It consists in
constraining a system to reach the desired state from an initial state within a
given time interval. When the desired objective affects only a sub-region of
the domain, the control is said to be regional. The purpose of this paper is to
study a particular case of regional control using cellular automata models
since they are spatially extended systems where spatial properties can be
easily defined thanks to their intrinsic locality. We investigate the case of
boundary controls on the target region using an original approach based on
graph theory. Necessary and sufficient conditions are given based on the
Hamiltonian Circuit and strongly connected component. The controls are obtained
using a preimage approach.
