Cross + 1 F2L Tab — Algorithm & How to Use It
This tab doesn't just find a cross — it picks the cross direction that makes the first F2L slot easiest. The app analyzes all 6 cross colors, ranks them by cross length and F2L recognizability, then suggests an F2L sequence for the chosen slot.
What problem does this tab solve?
In real CFOP solves, the best cross direction is sometimes not the absolute shortest one, but the one that leaves an easy-to-see, easy-to-recognize, or short first F2L case. The Cross + 1 F2L tab simulates that thinking: cross + the next F2L slot are treated as one combined inspection decision.
Basic vs. Pro
The Basic / Pro toggle works like the Cross tab (and shares the same saved preference). The key difference when combined with F2L:
| Criteria | Basic | Pro |
|---|---|---|
| Cross used for ranking | Shortest QTM (every color) | Ergonomic for the selected color; fast QTM for the other 5 |
| Ranking the 6 directions | Fewer cross moves → easier F2L recognition | Ergonomic cost + F2L cost + slot-breaking penalty |
| 3D viewer | Focused on cross (+ basic F2L) | Full cube, F2L highlighted |
Step 1 — Scan all 6 cross directions
For each cross color, the engine tries 4 cube orientations and computes a cross solution. Results for each color are pushed to the UI progressively — you don't have to wait for all 6 colors before seeing the table.
Step 2 — Score F2L recognition (no MCTS yet)
After each candidate cross solution, the app simulates the resulting cube state and scores all 4 F2L slots based on speedcubing recognition criteria, for example:
- +100 — corner and edge already paired on U.
- +50 — both pieces on U but not paired.
- −30 — a piece is stuck / a hard-to-recognize case.
- Front-facing slots (FR, FL…) are preferred on ties.
This stage doesn't run MCTS — it's just a fast way to rank the 6 directions. That keeps the 6-color table appearing quickly and lightweight, compared to running a full search for every direction.
Step 3 — MCTS for the winning slot
Once the best cross direction is chosen (by tier), the engine runs MCTS once (~600 iterations) to find an actual F2L move sequence for the suggested slot. MCTS favors moves with low finger-trick cost — similar in spirit to Pro mode.
The UI shows: the F2L slot (FR / FL / BL / BR), why it was chosen (recognition), and the suggested sequence after the cross.
How to read the analysis table
- Cross move count — the length of the cross sequence for that direction.
- F2L slot score — the easiest slot after the candidate cross (recognition).
- Min — the best direction according to the algorithm (not always the plain shortest cross).
Try clicking through each color to compare: sometimes an extra cross move is worth it if the first F2L slot becomes a paired case — a real trade-off worth considering during inspection.
Cache & performance
Results are cached separately for the Cross + 1 F2L tab and for each Basic/Pro tier. Switching tiers for the same scramble restores instantly from cache. A new scramble triggers a fresh computation.
Suggested practice routine
- New scramble → open the Cross + 1 F2L tab.
- In Basic, check the Min direction and read the suggested F2L slot.
- Execute the cross + first F2L slot as suggested; compare it to what you'd pick during inspection.
- Switch to Pro to see a more realistic execution sequence for the same scramble.