Autor: Hildeberto Cabral

Hildeberto Cabral is Professor of Mathematics at the Federal University of Pernambuco in Recife, Brazil. He has published on periodic solutions, stability, and other topics in Hamiltonian systems and celestial mechanics. Florin Diacu is Professor of Mathematics and Director of the Pacific Institute for the Mathematical Sciences at the University of Victoria. He is the author of Singularities of the N-Body Problem and An Introduction to Differential Equations and coauthor of Celestial Encounters (Princeton).