Quote:
http://cube20.org/The hardest position for our programs. Hello, twisty puzzles legends, utillising the scramble for the «hardest
position», let us have a look at a sample solve illustrating the classic
block building technique and inserting algorithm(s)to cancel moves. In particular, we will see the optimisation of a first
«fewest moves» solution by moving the three-corner-cycle from the
end of the solution to the beginning (second solution) or by insertion
at a suitable position (third solution) in order to cancel some moves.
Quote:
http://cube20.org/The following position was the hardest for our programs to solve:

scrambleF U' F2 D' B U R' F' L D' R' U' L U B' D2 R' F U2 D2
first solution (block building)
block 2*2*2:
F B L2 D L' U' R2 B R' D (=10)
block 2*2*3:
B2 L' B2 L (+4 =14)
plus 1*2*2:
B' R' B R' (+4 =18)
block 2*3*3:
U R U' R' (+4 =22)
3*3*3: .
F' U2 F' D' F U2 F' D F2 .
U2 (+9+1 =32)
32 moves (40q, 32f, 32s) in <35 minutes

second solution (based on first)
3-corner-cycle: .
F' U2 F' D' F U2 F' D (F2... . (=9)
block 2*2*2:
...F) B L2 D L' U' R2 B R' D (-1+10 =18)
block 2*2*3:
B2 L' B2 L (+4 =22)
plus 1*2*2:
B' R' B R' (+4 =26)
block 2*3*3:
U R U' R' (+4 =30)
3*3*3:
U2 (+1 =31)
31 moves (38q, 31f, 30s) in <40 minutes
third solution (also based on first)
block 2*2*2:
F B L2 D L' U' R2 B R' D (=10)
block 2*2*3:
B2 L' B2 L (+4 =14)
3-corner-cycle: .
R' F R B' R' F' (R B) . (+8-2 =20)
plus 1*2*2: (B' R')
B R' (-2+4 =22)
block 2*3*3:
U R U' R' (+4 =26)
3*3*3:
U2 (+1 =27)
27 moves (32q, 27f, 25s) in <55 minutes


And now, for your viewing pleasure, check out the following animations.



computer-generated solutions by
http://software.rubikscube.info/JACube/JACube31c.zipjava -cp ACube3.jar ACube af
...
-UF -UR -UB -UL -DF -DR -DB -DL -BR -BL -FR -FL +UBL +ULF +UFR +URB -DLB -DBR -DRF -DFL
...
depth 12...
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L U' B R2 D R' F L U' L2 B' L' . U2 F2 D' L2 B2 R2 B2 U L2 D2 F2 (34q, 23f, 23s)
...
23 moves in <1 minute
...
depth 14...
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L D2 F' U L' B R' F' U' B2 L' U2 D F . R2 U F2 U B2 R2 D B2 (30q, 22f, 22s)
L B' U' F L D R B U' L U D' F2 R' . D F2 L2 D' R2 F2 L2 U (28q, 22f, 22s)
L B' U' F L D R B U' L E R2 B' . D R2 F2 D' B2 R2 F2 U (28q, 22f, 21s)
...
22 moves in <5 minutes
...
depth 15...
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L B2 U F R2 D L R2 B L2 R F D L2 F' . L2 F2 U' F2 L2 U (30q, 21f, 21s)
...
21 moves in <55 minutes
...
depth ??...
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20 moves in ?? hours