Non-bifurcation of critical periods from semi-hyperbolic polycycles of quadratic centers

David Marín, Mariana Saavedra, Jordi Villadelprat

In this paper we consider the unfolding of saddle-node \[ X= \frac{1}{xU_a(x,y)}\Big(x(x^μ-\varepsilon)\partial_x-V_a(x)y\partial_y\Big), \] parametrized by $(\epsilon ,a)$ with…