Observe permutation parity

The Basic 4PAIRs are placed in the shape as shown on the right, where the silver center represents the F face, and the black center represents the U face.

Observe permutation parity of Base 4PAIRs

The permutation parity can be judged by the position with the color below

Even permutation:     Odd permutation:

Permutation parity of the other three corners on the U layer excluding Hub Corner

For the convenience of explanation, use to represent the Hub Corner that does not consider the twist orientation.
The U layer is as shown on the left, and observe the two corners of the arrow head and tail in the direction of the arrow.

The following three are all even permutations, and those that do not belong to the following three are odd permutations.

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