# Rubik solution – bottoms up

This method of solving professor Rubik’s cube completes the cube in layers starting from the bottom. To assist in solving the rubik cube we provide diagrams that show how blocks will move when a certain sequence of face turns is performed.

The key diagram identifies for any one move sequence a front face and thereby a left, right, bottom, top and back faces. The key diagram and the move sequences below show the blue face as the front face but any colour face can be the front face for the duration of a move sequence.

In performing the moves hold the cube as in the diagram with the front right edge facing you. The key diagram also shows how lower case letters call for anti-clockwise rotations of faces and capital letters call for clockwise rotations of those faces.

The stages in completing the cube from bottom up are as follows:-
1. The four bottom face edge blocks are put in position.
2. The four bottom corner blocks are put in position.
3. The four side edge blocks are put in position.
4. The four top edge blocks are put in position.
5. The four top corner blocks are put in position.

Stage 1 – Pick a colour that is going to be your bottom face. I usually choose white. It will be the bottom face throughout the cube solution. I provide no help diagram for this stage but give two pieces of advice. Aim to get a bottom edge block on the top level above its “home” position and with a matching side face colour. A 180 degree face turn will finalise that block. The second piece of advice is that if at any stage you have to turn a side face that has a bottom block correctly positioned make sure to put that block back in position as soon as you can.

Stage 2 – Look for bottom corner blocks at the top level that have the cube bottom face colour on one of the cube side faces. Rotate the cube so that the lower front corner is the “home” position for this block. One of the two moves illustrated below, will transport and finalise your selected block in its “home” position bottom front. Position your selected block ( by rotating the top face ) and perform the chosen move sequence.

When there are no such blocks that meet the above criteria look for blocks at top level that have bottom face colours pointing skyward. Rotate the cube so that the “home” position for that block is bottom front, then rotate the top face to position the selected block above its home position. Now turn either the front cube face anti-clockwise or right face clockwise so that this block has its bottom face colour on the cube side of the top layer. Note that this rotation disturbs already finalized bottom layer blocks so turn the top layer to position this block at the top rear before reversing the side face rotation you made. Now you can proceed as in the previous paragraph.

If you have to move a corner block from the bottom layer to the top layer for further treatment then position such a block at the bottom front and do either of the above moves

Stage 3 – Find a middle layer edge block on the top face. Rotate the cube as a whole so that the vertical edge facing you is the “home” position for the selected block. Select from the moves illustrated below the one that will deliver the desired result. Rotate the cube top face to appropriately position the selected edge block and do the chosen move. Repeat this process as necessary for other vertical edge blocks.

If at some stage you need to move a middle layer edge block to the top face simply rotate the cube so the block is at the font facing edge and do either move.

Stage 4 – First rotate any top edge blocks that do not have their top colour face uppermost. If four blocks need rotation perform either of the block flipping move sequences illustrated below so that you are left with two to rotate. Then do the move sequence that rotates that pair. When completed all top face edge block colours match the top face colour creating a colour cross.

Now rotate the top face to see the alignment you have between those top face edge blocks and the cubes coloured side faces. You may be lucky and have full alignment in which case proceed to the next stage. More likely is you can align two faces and need to swap the position of the other two or you have been unlucky and cannot align a pair.  The edge re position sequence illustrated above should secure alignment. Perform it twice if need be.

Stage 5 – With the edge blocks aligned look for corner blocks correctly located (but probably in need of rotation). If all corner blocks are correctly located then proceed as per the next paragraph. If one is correctly located then choose from the two move sequences illustrated below the one that delivers the desired result. If neither of the above apply choose from the two move sequences so as to deliver one correctly located block and then the sequence that will correctly locate the other three.

Now we have correctly located our top corner blocks some of them will need rotating. Two rotation moves are provided, one clockwise and one anticlockwise. Do not now rotate the cube – hold it in the same position until all corners have been completed following the instructions below.

Pick a top corner block in need of rotation and rotate the top face of the cube to bring that block to the top front position. Select and perform the clockwise or anticlockwise rotation move illustrated above to rotate and finalise that block.

Having done the above move the cube will appear messed up but don’t rotate the cube. Simply keep repeating the process in the above paragraph until all corner blocks are finalised and the cube is finalised