AN ANALYTIC CENTER MANIFOLD FOR A SIMPLE EPIDEMIOLOGIC MODEL

A simple epidemiological model whose dynamics are described by a pair of nonlinearly coupled Lotka-Volterra oscillators is shown to have a t wo-dimensional center manifold. This center manifold turns out to be i dentical to the center eigenspace and is thus analytically determinabl e. On the center manifold, the system is reduced to a single Lotka-Vol terra oscillator.