文摘
In this article, using an infinite-dimensional equivariant Conley index, we prove a generalization of the profitable Liapunov center theorem for symmetric potentials. Consider a system \((*)\; \ddot{q}= -\nabla U(q)\), where U(q) is a \(\Gamma \)-invariant potential and \(\Gamma \) is a compact Lie group acting linearly on \({\mathbb {R}}^n\). If system \((*)\) possess a non-degenerate orbit of stationary solutions \(\Gamma (q_0)\) with trivial isotropy group, such that there exists at least one positive eigenvalue of the Hessian \(\nabla ^2 U(q_0)\), then in any neighborhood of \(\Gamma (q_0)\) there is a non-stationary periodic orbit of solutions of system \((*)\).