TheChaiCuber
Regular
dang, thats really cool! ill pass tho xDYeah, OLL parity happens when the wings have odd permutation parity, which happens when the total number of inner layer quarter turns to get to that state from a solved cube is odd.
If you trace out the wing cycles like you would in 4BLD during inspection, you can tell if the scramble did an even or odd number of inner layer quarter turns, and you can use that to ensure that when you finish solving centers the number is even, thus avoiding OLL parity - after centers are solved you can stop caring because then there's no reason to use an alg which has an odd number of inner layer quarter turns unless you're solving OLL parity.
It's been known for years, but it's really difficult and very few people are inclined (or able) to do it.
