Edge pairing

With the centres done, the remaining dedges are paired a few at a time: line up wings that belong together on opposite sides of a slice, turn the slice to join them, replace the joined dedges with unpaired ones using an outer-turn sequence that keeps the joined pairs safe, and turn the slice back so the centres are restored. The usual grouping after Yau is 3-2-3: three dedges at once, then two, then three. Plain reduction often pairs six, then the last two (6-2).