Mean-zero score identity under quadratic-mean differentiability
= Mean-zero score identity under quadratic-mean differentiability
{title2=$Pg=0$}
For a <differentiable-in-quadratic-mean path>, normalization gives $\langle(\sqrt{p_t}-\sqrt p)/t,\sqrt{p_t}+\sqrt p\rangle=0$. The two factors converge in <L2 space> to $g\sqrt p/2$ and $2\sqrt p$. Continuity of the <inner product> therefore gives $Pg=0$. This proves <score function> centering without differentiating the density <integral>.