"First, consider that the following formula detects 2-ness" Consider changing this to something like "First, consider that the following formula detects 2-ness among the numbers as we want them to be"? It wasn't immediately obvious to me that the starred chain's '-1*' didn't satisfy the equation.

Er, also, you might want to have only one of the interlocutors beginning sentences with "Er" lest we lose track of which is supposed to be current-you. ;)

But yeah, a nice exposition!