  After introducing commutativity concept and summarizing the relevant
literature, this work is focused on the commutativity of feedback conjugates.
It is already known that a linear time-varying differential system describing a
single input-single output dynamical system is always commutative with its
constant gain feedback pairs. In this article, it is proven that among the
time-varying feedback conjugates of a linear time-varying system, constant
feedback conjugates are the only commutative feedback pairs and any of the
time-varying feedback conjugates cannot constitutes a commutative pair of a
linear time-varying system.
