🍔 is the set of integers modulo 2 (more literally, if two integers differ by an even integer you consider them the same). I can write out more in a bit.
Edit: this previous post has some good comments, and you can find some of the notation and the answer on the wikipedia page for cohomology ring (they use F2 for integers mod 2 and RPn instead of Pn(R)). I don’t know enough algebraic topology to actually know why that’s the answer but I can at least answer these:
The first definition of 🍕 with the contravariant thing also doesn’t parse for me, what does that “-” mean in the function arguments?
I assume it’s shorthand for saying that if you define f(x) = 🍕(x, B) then f : C --> Set is contravariant.
In the definition of 🌭, what is the n (or the P)? ChatGPT started yapping about real projective space, but I’m not sure if that’s correct.
Ah thanks for the info! Together with the other in-depth comment this is painting a good picture of what’s happening. Though I have some terms to study before I’ll get it.
🍔 is the set of integers modulo 2 (more literally, if two integers differ by an even integer you consider them the same). I can write out more in a bit.
Edit: this previous post has some good comments, and you can find some of the notation and the answer on the wikipedia page for cohomology ring (they use F2 for integers mod 2 and RPn instead of Pn(R)). I don’t know enough algebraic topology to actually know why that’s the answer but I can at least answer these:
I assume it’s shorthand for saying that if you define f(x) = 🍕(x, B) then f : C --> Set is contravariant.
It’s not the notation I’m used to (I’d also think of power sets first), but I think it’s n-dimensional real projective space.
Ah thanks for the info! Together with the other in-depth comment this is painting a good picture of what’s happening. Though I have some terms to study before I’ll get it.