2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/140340This article is meant as a mathematical appendix or comment on [BT]. We first consider the notion of transcritical bifurcations of fixed points of general area-preserving maps, and then adress some questions related to [BT] on bifurcation in Poincaré maps of 2-dimensional Hamiltonian systems. [BT] M. Brack and K. Tanaka, arXiv:0705.0753Symplectic GeometryDynamical SystemsChaotic DynamicsLaTeX, 13 pagestext