Rohin Shah comments on Beliefs at different timescales

[Rohin Shah]

I find the current notation fine, but if you want to make it more explicit, you could do

$\sum _{x_{k+2}}\sum _{x_{k+3}}\cdots \sum _{x_{k+n}}{P}_n(\dots )$

[Nisan]

Thanks, I made this change to the post.