Rafael Ortega

BOUNDEDNESS IN A PIECEWISE LINEAR OSCILLATOR AND A VARIANT OF THE SMALL TWIST THEOREM

Consider the differential equation

The stability of the equilibrium of a nonlinear Hill's equation

\ddot{x} +n^2 x+h_L (x) =p(t),

The index of lyapunov stable fixed points in two dimensions

where

The twist coefficient of periodic solutions of a time-dependent Newton's equation

n=1,2,\dots

On the Families of Periodic Orbits of the Sitnikov Problem

is an integer,

Parabolic fixed points and stability criteria for nonlinear Hill's equation

p

Bounded solutions of second order semilinear evolution equations and applications to the telegraph equation

is a

Non-continuation of the periodic oscillations of a forced pendulum in the presence of friction

2\pi