Pavel Golubtsov

Polymorphisms are a class of multivalued measure-preserving self-maps of Lebesgue spaces. Specifically, polymorphisms can be used to describe the change in the adiabatic invariant due to separatrix crossing. In this case, it consists of smooth functions mapping the unit interval into itself. In addition, there are some conditions these functions must satisfy in a typical case, namely, that their endpoints form rigid structures that persist under small perturbations. Here we will describe these conditions.