PLL Ab
The algorithm, how to recognise it and how to practise it without cheating.
Recommended algorithm
x R2 D2 R U R' D2 R U' R x'9 moves
Alternatives
R2 B2 R F R' B2 R F' R9 moves
How to recognise it
All the edges are already solved and one side has headlights. Hold the headlights on the right: the solved 2×2 block is then at front left.
Its inverse is another case
Do the Ab algorithm backwards, x R' U R' D2 R U' R' D2 R2 x', and you are solving Aa.
That's why CubeDojo never scrambles Ab that way: it builds a random state with the case fixed, so you practise Ab and not Aa.
Practise Ab now
Random-state scrambles, a timer and spaced review. Free, on the web and on your phone.
Other cases: Adjacent swap
Aa
x R' U R' D2 R U' R' D2 R2 x'Adjacent swap · 1/18FR' U' F' R U R' U' R' F R2 U' R' U' R U R' U RAdjacent swap · 1/18GaR2 U R' U R' U' R U' R2 U' D R' U R D'Adjacent swap · 1/18GbR' U' R U D' R2 U R' U R U' R U' R2 DAdjacent swap · 1/18GcR2 U' R U' R U R' U R2 U D' R U' R' DAdjacent swap · 1/18GdR U R' U' D R2 U' R U' R' U R' U R2 D'Adjacent swap · 1/18Jax R2 F R F' R U2 r' U r U2 x'Adjacent swap · 1/18JbR U R' F' R U R' U' R' F R2 U' R'Adjacent swap · 1/18RaR U' R' U' R U R D R' U' R D' R' U2 R'Adjacent swap · 1/18RbR2 F R U R U' R' F' R U2 R' U2 RAdjacent swap · 1/18TR U R' U' R' F R2 U' R' U' R U R' F'Adjacent swap · 1/18