Lesson 4
Parity
Sometimes edges have an odd number of targets. This means a single edge-swap (T-perm) at the end would leave two corners swapped. We fix this with a special parity algorithm before starting corners.
When Does Parity Happen?
A 3x3 cube permutation must be even overall. If your edge cycle has an odd number of targets, your corner cycle will be "off" by one swap. You detect this during memo: count your edge targets.
Rule:
Odd number of edge targets → parity exists. Apply the parity alg between edges and corners.
Parity Algorithm
D' L2 D M2 D' L2 D
Execute this once after finishing all edge targets and before starting corners.
Full Solve Flow with Parity
- Memorize edges and corners separately.
- Solve all edge targets using T-perms.
- If edge target count is odd: apply
D' L2 D M2 D' L2 D - Solve all corner targets using Y-perms.
- Remove blindfold and celebrate.