ELI5: Explain Like I'm 5

Rook polynomial

Imagine you have a chess board, and you want to know how many ways you can put rooks on it without any of them being able to attack each other. A rook can move horizontally or vertically, but not diagonally.

The rook polynomial is a formula that helps you figure this out for any size chess board. It looks like a bunch of letters and numbers, but it's really just a way to count all the different ways you can place the rooks.

For example, if you have a 4x4 chess board, you can use the rook polynomial to find that there are 40 different ways to place the rooks. But if you have a bigger board, like an 8x8 or a 12x12, the number of ways to place the rooks gets much bigger!

The rook polynomial takes into account things like symmetry and repetition, to make sure you don't count the same arrangement twice. It's a really helpful tool for mathematicians and chess players alike!