A transformation of PDE systems related to the Drach theorem

We will define a new transformation of PDE systems as follows. Given a particular PDE system F, there is a new system ˆF whose solutions are the spaces of elements attached to the solutions of F. We will show that the system ˆF is a second order PDE system in a single unknown. As an application, we will derive as well a global version of the Drach theorem.  2003 Elsevier Inc. All rights reserved