Rarity invites Twilight for an impromptu lesson in fashion design, and in so doing, discovers an unexpected fatal flaw in her own sense of style. Twilight has an answer, of course. It only requires a small amount of set theory...

Just a tongue-in-cheek exploration of what might really happen if Rarity's spur-of-the moment fashion sense met Twilight's encyclopedic nerdiness head on.

This is set somewhere in the middle of Season 4. Because amongst other things, I really miss the Golden Oak Library...