Now, before you solve corner permutation, you’ll want to fix parity. I do this by recognizing the PLLs of both layers. It’s a lot like recognizing permutation parity on 4×4: if the PLL is a valid 3×3 PLL, the layer has no parity. Otherwise, it does. If both layers have parity, or neither does, the whole puzzle does not have parity. If only one layer has parity you need to perform a parity fix.

The optimal way to solve parity is this: /3,3/1,2/4,-2/-4,2/-1,-2/-3,-3/.

For those of you who care, this changes parity because the middle / (in between the 4,2s) swaps 3 pairs of corners, for an overall odd number of swaps.

Without leaving cube shape, all possible twists do an even number of swaps: 2 pairs of corners & 2 pairs of edges.

This is the best time to perform parity in my opinion, because it preserves orientation but messes up CP. Some people use a (much) longer parity alg but don’t recognize parity until after CP is solved. This saves a bit of recognition time but the alg is nasty. Plus, my way leads into CP parity later.

The next step is Corner Permutation, so head on over there when you’re ready.