OLL Corners Tutorial — Rubik's Cube (LBL)
Recap
The yellow cross is done on top. This step orients the four top corners yellow-up too, completing a full yellow top.
This step uses two triggers: Sune (R U R' U R U2 R') and Anti-Sune (R U2 R' U' R U' R'). R / U / U2 are basic notation — see Fundamentals if rusty; assumes you've finished the OLL Cross.
Goal
A full yellow top = all four top corners yellow-up. This step only handles orientation (yellow up), not position — which slot a corner sits in doesn't matter; permuting positions is the later PLL step.
Recognition
Recognition looks at how many of the 4 top corners are yellow-up — you count corners here, not edges (that was the cross step). Ignore side colors; only watch which way the yellow sticker faces: on top (up) or on a corner's side.
Count yellow-up corners: 1 = a fish — rotate the single yellow-up corner (the head) to front-left, then check the front-right corner's yellow sticker: front = Sune, right = anti-fish (the two shown at left); 2 — check relative position: adjacent or diagonal; 0 = all on the sides; 4 = done.
Two of those groups split into a mirror pair of looks — the two-adjacent case (same-face vs opposite) and the no-corner case (two-pair vs one-pair). You don't need to memorize them: just match your top to one of the seven pictures below.
Why is the up-count never exactly 3? (mod-3 conservation)
Each top corner has an orientation value 0 / 1 / 2 (mod 3): 0 = yellow-up, 1 and 2 are the two twisted directions. On any legally-turned cube, the sum of all corner orientation values is always 0 (mod 3) — a conservation law for corner twist (you can't twist a single corner in isolation; every move twists corners in balanced groups). F2L is done, so the bottom four corners are all 0, which forces the top four to also sum to 0 (mod 3). "Exactly 3 up" = three 0s + one 1 or 2, summing to 1 or 2 ≠ 0 — a violation, so it's impossible. Hence the count is only 0, 1, 2, or 4. This mirrors the OLL-cross "edges flip in pairs": that's mod-2 conservation, this is mod-3.
Solve demo
This step uses a uniform flow: whenever it isn't a fish, do one Sune to turn it into a fish; then re-identify it (Sune or anti-fish), re-hold, and apply the matching trigger. The demo below starts from a two-adjacent·opposite case: do Sune → it becomes an anti-fish, U′ re-hold, then Anti-Sune → done. That's one full pass of “do Sune → observe → re-hold → solve the fish.”
- Two · oppositeRUR'URU2R'（Do Sune）
- Anti-fishU'（Re-hold U′）
- Anti-fish (held)RU2R'U'RU'R'（Do Anti-Sune）
- Done
How
Count how many top corners are yellow-up: 1 → one trigger; 0 or 2 → two triggers (one Sune to reduce to a fish, then one more). At most two triggers for any case.
Both triggers only re-orient the top corners — they leave the cross and the bottom two layers untouched. The key is the hold: the seven pictures below show each case in its correct hold — match the picture; for the fish apply the matching trigger, for the rest do one Sune to reduce to a fish.
① Fish (one trigger) — 1 yellow-up: tell Sune from anti-fish, hold right, apply one trigger, done.
Only one yellow-up; recognized as a Sune fish by the tell above (the FR corner's yellow faces front). → head at front-left (as shown), apply Sune → done.
Only one yellow-up; recognized as an anti-fish (the FR corner's yellow faces right). → head at back-right (as shown), apply Anti-Sune → done.
② Reduce to a fish first (two triggers) — 0 or 2 yellow-up: hold as shown → one Sune makes a fish → re-identify, re-hold → one more.
The two yellow-up corners sit on the same face, like a pair of headlights. → Sune turns it into an anti-fish; solve that as one.
The two yellow-up corners sit on adjacent faces, pointing opposite ways. → Sune turns it into an anti-fish; solve that as one. (This is the demo case.)
The two yellow-up corners sit on opposite (diagonal) slots. → Sune turns it into an anti-fish; solve that as one.
No yellow-up; of the four side yellows, one pair shares a face. → Sune turns it into a Sune fish; solve that as one.
No yellow-up; the side yellows sit in two opposite pairs. → Sune turns it into a Sune fish; solve that as one.
Why does one Sune always reduce to a fish?
Each of the five non-fish pictures is a carefully chosen hold — from that hold, a plain Sune happens to flip the three un-oriented corners into a 1-up fish. Note: it's not that *any* Sune works — only from the pictured hold does Sune reduce to a fish, which is why we stress “hold as shown.” From a wrong hold, Sune may turn it into a different non-fish shape, not a fish.
What does the Sune trigger actually do?
Sune (R U R' U R U2 R') uses only R and U turns, so it touches only the four top corners — the bottom two layers and the yellow cross stay put, which is exactly why it's safe at the OLL stage. It re-orients the top corners: it leaves one corner alone (the head) and flips the other three's yellows up — the mechanism by which it solves a fish. Anti-Sune is Sune's exact inverse (do one then the other and the cube is unchanged); together they cover any corner orientation.
How do 27 orientations become 7 cases? (combination distribution)
Four top corners, each with 3 orientations (0/1/2), naïvely give 3⁴ = 81 states. But a legal state requires the four orientation values to sum to 0 (mod 3) (the conservation law from Recognition above), leaving 81 / 3 = 27. Counting them by how many yellows point up:
| Yellows up | States | Cases |
|---|---|---|
| 4 | 1 | done |
| 3 | 0 | impossible (conservation) |
| 2 | 12 | Headlights / Chameleon / Diagonal |
| 1 | 8 | Sune / Anti-Sune |
| 0 | 6 | Pi / H |
| Total | 27 | 7 cases + done |
Of those 27, a U turn (a different hold) counts as the same case — so they collapse into 7 recognition cases + done, the seven pictured above. The "3 up" row is exactly 0, which is why you never meet it.
Pitfalls
A few common traps:
- Wrong fish-head direction: the trigger not only fails to finish, it regresses to 0 or 2 up (you must reduce again). For a fish, always hold the head at front-left first.
- Mixing up Sune / Anti-Sune (wrong trigger): the result isn't all yellow — re-identify and apply again. Tell them apart by: head to front-left, check the front-right corner's yellow — front = Sune, right = anti-fish.
- Expecting a 0- or 2-up case to finish in one trigger: one trigger only turns it into a fish (1 up) — you still need one more.
Practice
Scramble a cube and solve up to the yellow cross, then stop at the top. Drill the loop “count corners → recognize the case → hold → trigger” until all seven cases reach a full yellow top. Once the top is all yellow, the next step permutes the top corners and edges (PLL).
Practice corner orientation