A Degenerate Hopf Bifurcation Theorem in Infinite Dimensions

Abstract

A Hopf bifurcation theorem is established for the abstract evolution equation $\frac{\mathrm{d}x}{\mathrm{d}t}=F(x,\lambda )$ in infinite dimensions under the degeneracy condition $Re{\mu }^{\prime }({\lambda }_0)=0$ and suitable assumptions. The stability properties of bifurcating periodic solutions are also derived. Interestingly, it is shown that a transcritical Hopf bifurcation still can occur at ${\lambda }_0$ although the stability property of the trivial solutions does not change near ${\lambda }_0$. Our results do not require the analyticity of $F$. The main tools are the Lyapunov--Schmidt reduction and a Morse lemma. Applications to a multi-parameter diffusive predator--prey system discover new branches of periodic solutions.

The last part in the proofs of Theorem 2.2 and Corollary 2.3 has been revised