On two-dimensional area-preserving diffeomorphisms with infinitely many elliptic islands (Q5934433)

The authors prove existence of \(C^r\)-smooth \((r\geq 6)\) area-preserving symplectic diffeomorphisms which have, in a bounded domain of the phase space, infinitely many isolated generic elliptic periodic points and, as a result, infinitely many elliptic islands. Note that they study two parameter families of maps, that are diffeomorphisms with simplest structurally unstable heteroclinic cycles.