I think the prior for aliens having visited Earth should be lower, since it a priori it seems unlikely to me that aliens would interact with Earth but not to an extent which makes it clear to us that they have. My intuition is that its probably rare to get to other planets with sapient life before building a superintelligence (which would almost certainly be obvious to us if it did arrive) and even if you do manage to go to other planets with sapient life, I don't think aliens would not try to contract us if they're anything like humans.

It ought to be a top-level post on the EA forum as well.

Well that's because it's meant to be quantifying over linear equations. $x$ and $y$ are not meant to be replaced but $a$ and $b$ are.

i is often used as an index in math, similar to how it is used as an index in for loops.

What would an event optimized for this sort of thing look like?

Why not generate it after it's posted publically?

Aaaa! I'm used to Arial or whatever Windows' default display font is. The larger stroke weight is rather uncomfortable to me.

Yarvin was not part of the CCRU. I think Land and Yarvin only became associates post-CCRU.

Maybe make a post on the EA forum?

It seems like if the SCP hypothesis is true, block characters should cause it to act strangely.