The non-invariance of hyperbolicity in partial differential equations
The non-invariance of hyperbolicity in partial differential equations
Hyperbolicity is shown to be not an absolute invariant in the sense defined by the author.Specifically, an example of a nonhyperbolic system is given with a partial prolongation which is hyperbolic.A large class of systems is found which is closed under modified absolute equivalence and which contains all hyperbolic systems.These …