The structure of the category of parabolic equations

Marina Prokhorova

Published 2005-12-05, updated 2009-05-29Version 5

We define here the category of partial differential equations. Special cases of morphisms from an object (equation) are symmetries of the equation and reductions of the equation by a symmetry groups, but there are many other morphisms. We are mostly interested in a subcategory that arises from second order parabolic equations on arbitrary manifolds. We introduce a certain structure in this category enabling us to find the simplest representative of every quotient object of the given object, and develop a special-purpose language for description and study of structures of this kind. An example that deals with nonlinear reaction-diffusion equation is discussed in more detail.