Monday, November 08, 2004

Rubik's Cube #2: The Solution

Here is the solution is in 5 steps. If not already, read part 1 first or this won't make any sense! The first step is to do the 4 top edges: TF, TR, TL, and TP. Try to solve it yourself with just knowing the basics and terminology first! The solution then moves downward, 4 cubits at a time. Solve each step in order and do each step several times before going to the next one, unless you just want to solve the cube and display it. Don't memorize it immediately except Step 1 which is considered very easy. When your ready to go to the next step, read it all before doing it with your cube.



STEP 1: Top Edges ~ TF, TR, TL, TP


A. Find the desired cue that is not correctly positioned
and move the cube so that it belongs at the TF
position. Rotate a face to move the cubit to the B
face. Rotate the B face so it is at the BF position.
If you displaced a correctly positioned cubit, move
it back now. F2. It is now correctly positioned.

B. If the desired cubit isn't correctly orientated, do
the following: F- T+ L- T-

This is a verbose way how to solve the top edges! If you
understand the terminology but don't know the 'why', observe
what you are doing. Do not go to Step 2 until you think the
above is stupid! For one, figure out how to correctly
position and orientate a cubit at the same time. This can be
done in 3 moves (4 if you need to put a cubit back in
position). Think ahead... don't drop the cubit to the B face
if you can position it without doing that.

Master this without referring to this step before continuing!
The steps will get harder and harder, and you should do this
step intuitively.



STEP 2: Top Corners ~ FRT, FLT, TRP, TLP

A. Find an incorrectly position corner cubit. If on the
T face, move the cube so the corner cube is in the
FRT position and do the following to move it to the B
face: R- B+ R+

B If on the B face, with the correct position at FRT,
rotate the B face so the corner cube is at BFR.

C If the T color is on the B face do this to orientate
it: R- B2 R+ B+

D. If the T color is on the R face: R- B- R+
E. If the T color is on the F face: F- B+ F+

Start with the corner cubits on the B face with the T color
not on the B face. That way the others may move to the B
face or get orientated, saving you some moves. Note there is
no real orientation moves except the third part of this step.
If you have to orientate a correctly orientated cubit, just
use one of the last two moves to move it down and then again
to send it back up.

The top third is now solved! This step is fairly easy to
memorize and if you just want to brag about one side solved,
go ahead and do this. It will actually make Step 3 easier.
You don't have to do this yet though. Step 3 is considered
moderately difficult to memorize.



Step 3: Middle Edges ~ FR, FL, RP, LP

Seq BF: B- R- B+ R+ B+ F+ B- F-
Seq BR: B+ F+ B- F- B- R- B+ R+

A. Look for an edge cube on the B face that belongs on
the equator. With the correct position at FR, rotate
the B face till the edge cubit is at BF (if the F
color is on the F face in this position) or BR (if
the R color is on the R face in this position). Do
one of the above sequences, depending on where the
cubit is.

B If there is none on the B face but there is
incorrectly positioned/orientated cubits on the
equator, just place it on the FR position and do
either of the two sequences (skipping the B- or B+ of
course!) to move it to the B face.

Two thirds done! Now comes the most difficult two steps!



Step 4: Bottom Edges ~ BFL, BFR, BRP, BLP

Switch: R- B- R+ F+ B+ F- R- B+ R+ B2
Orientate: R- B- R+ B- R- B2 R+ B2

A. Rotate the B face till you know you have the most
correctly positioned cubits possible. Use the switch
sequence above to switch the BFL and BFR cubits if
needed.

B. Correctly positioned, there is 7 patterns. The
'best' two have only one correctly orientated cubit
at the BFL position. Do the orientate sequence once
or twice to get them all correctly orientated; the
second one results in the other 'best' pattern. The
others will result in one of the 'best' patterns.
Since I lost Nourse's booklet, I'll leave it up to
you to figure out which of the remaining 5 should be
the F face!

Almost there! Note you can skip the B2 in the above
sequences to save a move. On the next step, parenthesis are
used to help you better visualize the moves.



Step 5: Bottom Edges ~ BT, BR, BL, BP

Position: (L- R+) F+ (L+ R-) B2
(L- R+) F+ (L+ R-)

Orientate: (L- R+) F+ (L+ R-) B- (L- R+) F-
(L+ R-) B- (L- R+) F2 (L+ R-)

A If there is no correctly positioned cubits, use the
position sequence to get one correctly positioned.

B If there is 1 correctly positioned, at BF, use the
position sequence once or twice to get them all
positioned.

C Now there is three patterns if not solved. 1) All
cubes not orientated, "Checker". 2) Two not
orientated at BF and BP, "H". 3) Two not orientated
at BL and BP, "Best". Doing Orientate then position
(also with the correct cubit at BF) will make pattern
#3 with the other two. With pattern #3, the cube
will be solved!

That's it! Note how the position sequence work. This moves
all but the BF cubits clockwise. If you need to move it
counter-clockwise, substitute F- for F+ and save yourself
from doing the sequence again.

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