Reciprocal transformations associated with admitted conservation laws were
originally used to derive invariance properties in non-relativistic gasdynamics
and applied to obtain reduction to tractable canonical forms. They have
subsequently been shown to have diverse physical applications to nonlinear
systems, notably in the analytic treatment of Stefan-type moving boundary
problem and in linking inverse scattering systems and integrable hierarchies in
soliton theory. Here,invariance under classes of reciprocal transformations in
relativistic gasdynamics is shown to be linked to a Lie group procedure.
Normal forms, canonical forms, and invariants of single input nonlinear systems under feedback