= Quartic-inflation endpoint estimate
{title2=$|\phi_e|\simeq M_P/\sqrt\pi$}
For $V=\lambda\phi^4/4$ and unreduced <Planck mass> $M_P$, the <potential slow-roll parameter> is $\epsilon_V=M_P^2/(\pi\phi^2)$. Setting it to one gives the displayed conventional endpoint. The exact end of scalar-dominated <accelerating expansion> is $\epsilon_H=1$, equivalently $\dot\phi^2=V$. Since <slow-roll> is failing near that point, a precise endpoint requires evolving the full <inflaton equation of motion>; potential and kinetic criteria evaluated with a failing approximation need not give the same order-one coefficient.
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