= Fold delay
{title2=$\Delta t=O(\varepsilon^{2/3})$}
Near a nondegenerate <fold point of a critical manifold> crossed with nonzero slow speed, the local balance can be written $\varepsilon\dot x=y-x^2$, $\dot y=-1$ up to nonzero scalings and higher-order terms. A time interval $T$ gives $y=O(T)$; balancing $x^2$ with $y$ gives $x=O(T^{1/2})$, and balancing $\varepsilon x/T$ with $T$ gives $T=O(\varepsilon^{2/3})$, $x=O(\varepsilon^{1/3})$. This layer delays departure from the fold relative to an instantaneous singular jump. It differs from the order-$\varepsilon$ fast motion away from the fold.
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