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⬅️ Previous capture (2023-01-29)
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My favorite twisty puzzle is the 4x4x4 cube, also known as Rubik's Revenge Cube. The even number of layers in the puzzle allows for trickier piece arrangements than on odd-numbered cubes, such as incorrectly-placed centers, an odd number of flipped edges, or a bad permutation parity among pieces. It's much more challenging, and much more fascinating to analyze, than the standard 3x3x3 Rubik's Cube.
The 4x4x4 is also the puzzle I've practiced speedsolving the most after the 3x3x3. Recently I purchased a stickerless version of the QiYi WuQue 4x4x4 by Mo Fang Ge, and it's inspired me to begin practicing more regularly again.
I currently use a reduction method to solve the puzzle. I gather all similarly-colored center pieces on their respective faces, then I pair up all similar edge pieces. This essentially reduces the state space of the puzzle from a 4x4x4 to a 3x3x3. Parity issues aside, the two cubes can be solved in exactly the same way at that point.
In the edge-pairing step of this method, I used to use the E slices (the layers between the U and D faces) as my working layers. I first used d (twisting the bottom two layers) to pair edges, but I can't perform d moves quickly, so I switched to using u instead. However, I still found my recognition to be slow, particularly for edges on the D layer or in the BL or BR positions. A few months ago I switched away from the E slices entirely; I now use the M slices (between L and R) to pair edges, and my recognition has improved significantly as a result.
I had some down-time yesterday, so I decided to pull out my old StackMat timer and see how much progress I've made on the 4x4x4. The result was surprising: the majority of my solves were under 1:10, and absolutely none of them (that didn't involve mistakes on my part!) were slower than 1:25. As I warmed up, my times dropped even more, and soon I was getting several times under one minute.
The highlight of the day was a new personal best time of 53.43 seconds. The scramble for that solve is below:
Rw R' Fw2 B' D2 B' Uw2 B' Rw B' U2 D2 B2 Fw2 Uw Rw F2 Rw Fw2 R2 Rw' Uw' Fw2 R2 Fw' U2 F2 Rw2 F2 Rw' D Fw2 D' Fw2 B L2 Rw' U2 Rw2 B
At time of writing, the world record for the 4x4x4 single is 16.79 seconds. I know I'll never get anywhere close to a time as ridiculous as that. But in the day when I first started getting into Rubik's Cubes, the world record for the 4x4x4 was 55.38 seconds, and I still think of that time as world-class speed. If I ever manage to breach the 50-second barrier, I think I'd be content with that.
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[Last updated: 2022-11-12]