Models the production and degradation of cyclin B that drives the early embryonic cell cycle.Cyclin B is degraded by APC/C. The activity of APC/C is modeled not through biochemical interactions, but through a 'functional response curve'. This can be ultrasensitive (with the parameter alpha=0). in this case the system does not oscillate. Importantly the response can be made bistable and the form of the bistability can be easily prescribed. With a bistable response, the system oscillates.The uploaded file corresponds to the model used for Figs.3H, I in the publication.