2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/134863We give an elementary proof of the analytic KAM theorem by reducing it to a Picard iteration of a PDE with quadratic nonlinearity, the so called Polchinski renormalization group equation studied in quantum field theory.17 pages, no figuresMathematical Physics37J40 ; 37J25text