Lesson 61 18 min Expert

COLL in practice

When to reach for it instead of OLL, how to recognise a case in the time you have, and the four edge permutations it leaves you with.

By the end you will be able to

Check edge orientation and choose between OLL and COLL without hesitating
Recognise a COLL case by family first and side stickers second
Finish with the four edge permutations and tell them apart at a glance
Judge the cases where running OLL and PLL is the faster choice

COLL is not an alternative to OLL. It is what you do instead of OLL on the one solve in eight where the last-layer edges arrive already oriented, and the decision has to be made in the same glance you were making anyway.

The check comes first

The last pair goes in and you look at the top face. If the four edges show yellow upwards — a complete cross, whatever the corners are doing — you are in COLL territory. If not, run OLL and PLL as you always have. That is the whole of the decision and it should take no longer than reading an OLL shape.

Seven families

The corner-orientation shapes are the ones you learnt for two-look OLL, and cubers name them by their pictures rather than their numbers.

Sune and anti-sune — one corner facing up, the other three twisted the same way round
Pi and H — no corner facing up at all, told apart by which pairs of side stickers line up
T, U and L — two corners facing up, told apart by where the other two point

Each family holds six cases, one for each way the four corners can sit relative to one another. One of those six is the OLL algorithm you already use, which is a pleasant thing to discover: run plain sune on the right sune case and the corners come out finished rather than merely oriented.

RUR^'URU²R^' 7

Sune as a COLL algorithm. Corners solved, and the edges left in a three-cycle — which is to say a U permutation, one of the four things that can be left.

RU²R^'U^'RU^'R^' 7

Anti-sune, doing the same job for its own family. Seven turns, two faces, and already in your hands.

RU²R²U^'R²U^'R²U²R 9

A COLL you do not know: nine turns, every one of them on R or U, which makes it quicker to execute than its length suggests. This is the sort of algorithm the set is full of.

RUR^'URU^'R^'URU²R^' 11

The H family — all four corners twisted in opposite pairs. Sune, then most of sune again. Learning the set family by family means learning shapes like this one rather than eleven unrelated turns.

Recognition, in two stages

Reading the family is free; you have been doing it for years. Telling the six cases within a family apart is the new skill, and it is done on the side stickers of the corners rather than the top.

Read the shape on the top face and name the family. Nothing new here.
Look around the sides for headlights — two corners on the same face showing the same colour. How many faces have them, and where they sit relative to the twisted corner, is what separates the six.
Turn the top face to the position your algorithm expects, run it, and finish with one of four edge cases.

The four edge cases

With the corners finished, the four edges must be an even rearrangement of themselves. There are twelve of those, and they fall into four shapes — the same four you met as the second half of two-look PLL, and now the only thing standing between you and a solved cube.

M²UMU²M^'UM² 7

Ua. Three edges cycle, one is already home: hold that one at the back. Eight of the twelve arrangements are a U permutation one way or the other.

M²U^'MU²M^'U^'M² 7

Ub. The same seven turns with every single U reversed, and nothing else.

M²UM²U²M²UM² 7

H. Every edge swaps with the one opposite. Symmetrical, so there is nothing to line up before you start. One in twelve.

M²UM²UM^'U²M²U²M^'U² 10

Z. Two pairs of neighbours change places. Hold it so the front and right edges are the pair that want to swap. Two in twelve.

When to leave it alone

When you are not certain within a second. OLL and PLL cost around twelve extra turns and no thinking. Hesitation costs more.
When you have only half the set. Covered above, and it is the commonest way people lose time to COLL.
In the middle of a competition average. A set you learnt last week will desert you under pressure. Bring it in when it is boring.

COLL, family by family All forty-two, grouped the way you should learn them, with move counts. Drill a family until it names itself The trainer shows a case, times your answer, and returns to the slow ones more often.