Third F2L pair -> OLS step -> PLL
The OLS step is the step between the Third F2L pair and the PLL.
OLS, an acronym for Orientation of the Last Slot, is a last slot method used to skip any OLL case while simultaneously solving the last F2L pair. All OLS cases can be solved using one of the algorithms found in VLS or HLS. If the pair cannot be solved using RUR' or RU'R', it can be intuitively changed to be able to do so. For example, if you were to set up this case (RU'R'URU2R'), the pair can be easily changed to an HLS case by intuitively doing this algorithm (RU2R'U'). However, setup moves and OLS can be done at the same time if the correct algorithms are used. Unfortunately, this would require up to 17,712 algorithms so it is not put into full use by any human. This method is quite helpful with decreasing times once the solver gets used to using the algorithms. Some notable speedsolvers who use parts of this method from time to time include Feliks Zemdegs, Seung Hyuk Nahm, and Mats Valk to name a few.
As previously stated, OLS is mainly split into two groups: VLS and HLS. These two groups are split into 8 subsets, each, that are based on edge misorientation. The subsets under VLS include WV, UF, UL, UB, UFUL, ULUB, UFUB, and all edges. The subsets under HLS include SV, UF, UL, UR, UFUR, UFUL, ULUR, and all edges. Each of these subsets has 54 algorithms, including mirrors. It is usually recommended to first learn WV, then SV, followed by the rest of VLS, and finally the rest of HLS.
- Move count is decreased by about 4 moves compared to normally doing the last F2L pair, then OLL.
- It requires less look ahead if implemented into solves, compared to doing the last F2L pair and OLL. So, although it only saves 4 moves, decreased look ahead can help reduce your solve times.
- Increased chance of a last layer skip.
- There are a total of at least 864 algorithms, including mirrors.
- Because of the first point, this means that if the solver were to learn full VLS and HLS, it would take over a year to learn if 2 algorithms were learned per day.