Role of saddle tori in the mutual synchronization of periodic oscillations BalanovAlexander G. JansonNatalia B. AstakhovV.V. McClintockP.V.E. 2006 We show that in the mutual synchronization of periodic oscillators, besides an attracting torus, there is also a saddle torus that plays an equally important role. We demonstrate that the saddle and stable tori form an elegant structure, allowing for a variety of phenomena, both known and new, related to the origin and evolution of coexisting synchronous regimes (phase multistability).