tailcalled comments on Price’s equation for neural networks

[tailcalled]

I’ve been meaning to write for a while now:

I’ve realized that since the derivative is infinitesimal, we can actually strengthen the covariance niceties a lot. If $f$ and $g$ are arbitrary functions, then I believe that:

$ntcov\left(f\right(x),g(y\left)\right)=Jf\left(x\right)ntcov(x,y)Jg(y{)}^{\top }$