Mechanical structure: The fourth-order cube is much more complicated than the third-order cube. Its composition is divided into two categories. One is that the center is a sphere, and each surrounding small block is connected with the slide rail of the center ball, and will slide on the slide rail along the direction of force when moving. The second is the fourth-order Rubik's cube with the axis as the core. The composition of this Rubik's Cube is very complicated. Besides the central ball and the surrounding squares, there are many accessories.
Order reduction method: regarding the fourth-order Rubik's cube, the most commonly used method is order reduction method. The simple explanation of order reduction method is to reduce the high-order Rubik's cube to the model of low-order Rubik's cube, and then complete it with the solution of low-order Rubik's cube. At present, Rubik's cube community uses reduction method to solve high-order Rubik's cube.
Special circumstances: If there are special circumstances, it can be recovered by the third-order Rubik's Cube PLL formula.
The fastest record: 19.36 seconds. feliks zemdegs came from Germany.