Slow manifold
= Slow manifold
{title2=$f(x,y)=0$}
For a fast-slow system $\epsilon\dot x=f(x,y)$, $\dot y=g(x,y)$, the formal critical manifold is $f=0$. Where the fast <linearization> has <eigenvalues> with strictly negative real parts, trajectories rapidly approach a nearby attracting <slow manifold> and then evolve on the slow time. Near folds or loss of this spectral condition, simply imposing $f=0$ may fail.