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Looking for Charles Tsai 8-step 4x4x4 solver

mrCage

mrCage

Member
Joined
Jun 17, 2006
Messages
655
Does anyone have the source code for this solver? Or even better a description of each of the steps involved. I have been getting queries about it, as i wrote an online PHP implementation many years back. I no longer have access to any of the code, Besides HTML of course ... **sigh**

Any input is more than welcome:tu

I know Bruce Norskog worked on a 5-step solver also ...

Per
 
I think Josef Jelinek (ACube creator) helped Charles Tsai create his solver. And Bruce Norskog worked on a 5-step solver. That's some more clues to follow up ...

Per (qq, what's your name?)
 
Hi Per,

perhaps you have already found it but here goes:
Bruce's 5 step solver can be found here: http://www.speedsolving.com/forum/showthread.php?18615-Five-Step-4x4x4-Solver

Some cut n paste from Bruce’s post in the 4x4x4 linear FMC thread
http://www.speedsolving.com/forum/showthread.php?31779-4x4-Linear-Fewest-Moves-Challenge/page5

The solver uses these five steps:
Step 1: Make the cube <U,u,d,D,L2,l2,r2,R2,F2,f,b,B2>-solvable.
Step 2: Make the cube <U,u2,d2,D,L2,l2,r2,R2,F2,f,b,B2>-solvable.
Step 3: Make the cube <U,u2,d2,D,L2,l2,r2,R2,F2,f2,b2,B2>-solvable.
Step 4: Make the cube <U2,u2,d2,D2,L2,l2,r2,R2,F2,f2,b2,B2>-solvable.
Step 5: Finish solving the cube.

The scramble is from the weekly forum contest 2011-34, first speedsolve scramble:
L' Fw' L' Fw D' R2 D' Uw' L2 B' F2 L Rw2 F' Rw R2 B Fw Uw U2
L R' D R Uw2 B2 Fw F2 D' L Fw' Rw R2 B2 D2 F' D' L' D2 B'

The solution is:
Step 1: U2 Lw' D' d Lw' B2 U x' (7/7)
Step 2: L2 d Fw2 d R2 Dw' b Lw2 d f y (10/17)
Step 3: D f2 D U2 b' Lw2 d2 f2 D f (10/27)
Step 4: D R2 D F2 D B2 Lw2 D2 R2 D Bw2 U (12/39)
Step 5: Lw2 F2 D2 f2 u2 l2 b2 U2 L2 Bw2 Dw2 (11/50)

-----------------------------

Step 1
Orient the corner cubies, and put the u- and d-layer edges into those two layers. (A d-layer edge may be in u layer, and a u-layer edge may be in the d layer.)

Step 2
Put front and back centers onto the front and back faces into one of the twelve configurations that can be solved using only half-turn moves. Arrange u- and d-layer edges within the u- and d-layers so that they will be in one of the 96 configurations that can be solved using only half-turn moves.

Step 3
Put centers for left and right faces into the left and right faces so that they are in one of the 12 configurations that can be solved using only half-turn moves. This leaves the centers for the U and D faces arbitrarily arranged in the U and D faces. Put top and and bottom layer edges into positions such that the U or D facelet is facing either up or down. Also, put these edges into an even permutation.

Step 4
Put corners into one of the 96 configurations that can be solved using only half-turn moves. Put U and D centers into one of the 12 configurations that can be solved using only half-turn moves. Put all U- and D-layer edges into a configuration that can be solved using only half-turn moves. This consists of 96 possible configurations for the l- and r-layer edges, and 96 for the f- and b-layer edges.

I note that my solver program does not output any cube rotations. So steps 2, 3, and 4 may use a different set of allowed turns than what those steps are supposed to use. It is simply translating the moves due to the cube being in a different orientation than it's supposed to be for those steps.
 
Last edited:
Thanks everyone!

Charles himself sent me a detailed description of all the steps of his 8-step solver. And now we have the binaries also. Still looking for the source code i used to have access to.

Per
 
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