Monotonicity of the period map for the equation $-{\phi }^{\prime \prime }+\phi -{\phi }^k=0$

Fábio Natali, Giovana Alves

In this paper, we establish the monotonicity of the period map in terms of the energy levels for certain periodic solutions of the equation $-{\phi }^{\prime \prime }+\phi -{\phi }^k=0$, where $k>1$ is a real…