[1] Univ Fed Rio de Janeiro, Inst Matemat, Rio De Janeiro, Brazil
[2] Acad Sci, Math Inst, Zitna 25, Prague 11567 1, Czech Republic
[3] Univ Fed Rio de Janeiro, Polo Xerem, Rio De Janeiro, Brazil
[4] CNRS, UMR 5142, LMAP, Lab Math & Applicat, Bat IPRA,Ave Univ, F-64013 Pau, France
[5] Univ Bio Bio, Ave Colla 1202,Casilla 5-C, Concepcion, Chile