Step 4/4 · Faster reduction

Advanced parity

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Four wide OLL parity algorithms, two of which also fix PLL parity, and three PLL parity forms besides opposite edge pairs.

Goal

Fix 4x4 parity with the algorithms fast solvers use. This lesson follows Parity in the beginner method.

OLL parity: four algorithms

All four algorithms here use only U2 and wide turns (Rw, Lw), so they are easy to do fast. In exchange, they twist the top corners. Do OLL parity as soon as you see the flipped pair, and only then do OLL.

The two algorithms of the second case also swap two edge pairs, which fixes PLL parity. During OLL you cannot tell whether PLL parity is there. So either version is fine: about half the time, PLL parity is still left at the end.

PLL parity: four forms

PLL parity is not only two swapped edge pairs. The top layer looks like a case a 3x3 can never have:

  • Two opposite edge pairs swapped: the PLL parity case in the beginner Parity lesson.
  • Two neighboring corners, two diagonal corners or two neighboring edge pairs swapped: the last three cases here.

These three work the same way: PLL parity first, then a 3x3 PLL. F is in PLL: neighboring corner swaps, Na in PLL: diagonal corner swaps and Ua in 2-look PLL: edges of CFOP.

Common mistakes

  • Doing OLL first and fixing OLL parity after. The wide algorithm twists the corners you just solved.
  • Seeing two swapped corners and looking for a 3x3 PLL. None works; do PLL parity first.

Next lesson

This is the last lesson of faster reduction. The 3x3 stage has seven lessons in the beginner method, starting with White cross.

Step 1 / 18

Rw: 2 Right layers: turn 90°, front face goes up

While making the yellow cross, the top front edge pair is flipped: two yellow stickers face the front. Ignore the corners.

The flipped pair on top, at the front. The algorithm twists the top corners, so do it before OLL.

Step 1 of 18: Rw. 2 Right layers: turn 90°, front face goes up