RubiksIllusions

Rubik's Cube solution: Lars Petrus method

The basic idea of this method is to solve the whole Rubik's Cube from here moving only the two free sides, but if we try doing that we notice that some edges are ever not well oriented. In this step we have to well orient them.
Also if this step can seem incomprensible until you don't learn it, it is the easier.

In this step we have to do two things:

• understand what edges of the seven remaining are not well oriented. To do this we can move every edge in the position they should be, now we can understand if they are or not well oriented. Now that we know we can't do anything because we will orinent them in the next step;
• turn the edge the are not well oriented. There are evere an odd number of edges not well oriented, 0, 2, 4, 6, than it's possible well orient them in couples. The simpler mode is the sequence showed in the picture.

As we want only know if an edge should be well oriented if it would be in its position, we don't need to lose moves moving it there really.
It's easy to see if an edge is well oriented without moving it. Let's call the colors of the two central cubes of the free faces (the only ones we have to consider) A and B.
There are four simple rules to remember:

• an edge in the A side that has a face of color A near the central cube of A is well oriented;
• an edge in the A side that has a face of color A far the central cube of A is not well oriented;
• an edge in the B side that has a face of color A far the central cube of B is not well oriented;
• an edge in the B side that has a face of color A far the central cube of B is not well oriented;

Note per la redazione: l'articolo originale di Lars Petrus spiega a questo punto come risolvere tutti i casi che si possono presentare con 2, 4, 6, spigoli girati al contrario.
Tale spiegazione verrà ripresa in un secondo tempo in quanto, per ora, l'interesse di questo articolo si focalizza su come risolvere il Cubo.