The map g is constructed by perturbing B along the unstable (vertical) direction, maintaining the vertical foliation as a g-invariant foliation. We create on the unstable line of the fixed point p0=(0,0)\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$p_0 = (0, 0)$$\end{document} two new fixed points in such way that it changes the stable index of p0\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$p_0$$\end{document}, so that g is not uniformly hyperbolic