Notes on strict system equivalence

It is shown that strict system equivalence in Rosenbrock's sense is equivalent to the existence of a certain bijective mapping between the sets of solutions to the differential equations describing the system. This leads to a simple proof of the fact that the equivalence classes under strict system equivalence are well defined, although the dimension of the system matrix is not uniquely defined. It is also shown that equivalence in Wolovich's sense is the same as strict system equivalence.