Correspondence between the parameters of the models ℳ(14, 25, 28) and ℳ(5, 8, 15). Parameters of the first model are gathered into monomials that are parameters of the reduced model. The integers on the arrows connecting parameters represent the corresponding powers of the parameters in the monomial. The critical monomials are connected to the property on which they act upon (here sustained oscillations). Thus, an increase of k21p 1= k2k9 favors significantly the oscillations.