3 papers
math.DS2026
Variance of vector fields -- Definition and properties
Jacky Cresson, Jordy Palafox
We give a self contained presentation of the notion of variance of a vector field introduced by Jean Ecalle and Bruno Vallet in \cite{ev} following a previous work of Jean Ecalle a…
math.DS2017
Lie algebras and geometric complexity of an isochronous center condition
Jacky Cresson, Jordy Palafox
Using the mould formalism introduced by Jean Ecalle, we define and study the geometric complexity of an isochronous center condition. The role played by several Lie ideals is discu…
math.DS2016
Isochronous centers of polynomial Hamiltonian systems and a conjecture of Jarque and Villadelprat
Jacky Cresson, Jordy Palafox
We study the conjecture of Jarque and Villadelprat stating that every center of a planar polynomial Hamiltonian system of even degree is nonisochronous. This conjecture is proved f…