4 · The yellow cross

The goal: a yellow cross on top. Only the edges count — the corners can be any colour.

We only look at the edges

At this step, ignore the four corners completely. Look only at the yellow centre and the four edges around it. The corners are dealt with in steps 6 and 7.

A single algorithm

F R U R' U' F'

It flips edges on the top face. Depending on what you have, you apply it once, twice or three times — that is the whole of this step.

The three cases

The dot
No yellow edge.
3 times

The L
Two edges at a right angle.
2 times

The bar
Two edges in a line.
1 time

How to hold the cube

This is the only delicate point of the step, and it is simple once understood.

The dotThe LThe bar

No particular orientation. Apply the algorithm: you get the L or the bar. Carry on with whichever case you got.

Turn U to put the L at the top left, as in the diagram: the two arms point up and left.

Apply the algorithm: you get the bar. Apply it once more.

Turn U so that the bar is horizontal, left to right.

Apply the algorithm once: the cross appears.

The shortcut

Dot → L → bar → cross. Each application moves you one notch along that chain. If you get the orientation wrong you move backwards along the chain without ever breaking anything else — it is risk-free.

Check

A clean yellow cross on top. The yellow corners are pointing every which way: that is normal and expected.