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  4 days ago by aschnell | Reply

  So the IDA* algorithm looks more clear now. It finds the solution by iterating the "game tree" but concentrates on the "best" path on every iteration. This is done using a heuristic.

  BTW: Back then test research papers were considered part of artificial intelligence so I'm also doing AI after all.

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So the IDA* algorithm looks more clear now. It finds the solution by iterating the "game tree" but concentrates on the "best" path on every iteration. This is done using a heuristic. BTW: Back then test research papers were considered part of artificial intelligence so I'm also doing AI after all.
 
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Reply to aschnell
So the IDA* algorithm looks more clear now. It finds the solution by iterating the "game tree" but concentrates on the "best" path on every iteration. This is done using a heuristic.
BTW: Back then test research papers were considered part of artificial intelligence so I'm also doing AI after all.
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  3 days ago by aschnell | Reply

  I have looked at various programs implementing IDA* based solvers. Many are unfortunately unfinished, broken and undocumented.

  The best so far is https://github.com/benbotto/rubiks-cube-cracker. Among other things it properly implements the index to the pattern databases while other programs seem to simply use a hash. It also gives speed measurements: It is really slow (several hours and more). The Korf IDA* solver is apparently still so slow.

  That made me think what the online solver at ruwix.com uses since it usually finds a good solution (never had more that 20 moves) in less than a minute. Maybe it uses another approach called the "Two-Phase-Algorithm" (https://kociemba.org/cube.htm). That also used IDA* but combines it with some group theory.

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I have looked at various programs implementing IDA* based solvers. Many are unfortunately unfinished, broken and undocumented. The best so far is https://github.com/benbotto/rubiks-cube-cracker. Among other things it properly implements the index to the pattern databases while other programs seem to simply use a hash. It also gives speed measurements: It is really slow (several hours and more). The Korf IDA* solver is apparently still so slow. That made me think what the online solver at ruwix.com uses since it usually finds a good solution (never had more that 20 moves) in less than a minute. Maybe it uses another approach called the "Two-Phase-Algorithm" (https://kociemba.org/cube.htm). That also used IDA* but combines it with some group theory.
 
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Reply to aschnell
I have looked at various programs implementing IDA* based solvers. Many are unfortunately unfinished, broken and undocumented.
The best so far is https://github.com/benbotto/rubiks-cube-cracker. Among other things it properly implements the index to the pattern databases while other programs seem to simply use a hash. It also gives speed measurements: It is really slow (several hours and more). The Korf IDA* solver is apparently still so slow.
That made me think what the online solver at ruwix.com uses since it usually finds a good solution (never had more that 20 moves) in less than a minute. Maybe it uses another approach called the "Two-Phase-Algorithm" (https://kociemba.org/cube.htm). That also used IDA* but combines it with some group theory.
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  about 20 hours ago by aschnell | Reply

  Another very old and interesting algorithm is the Thistlethwaite's algorithm that again uses group theory. I proved that any cube can be solved in 52 or less moves. It was later enhanced to use 42 moves (https://www.jaapsch.net/puzzles/thistle.htm). The already mentioned "Two-Phase-Algorithm" is based on the Thistlethwaite's algorithm. And there is also a version of Thistlethwaite's algorithm called Human Thistlethwaite Algorithm.

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Another very old and interesting algorithm is the Thistlethwaite's algorithm that again uses group theory. I proved that any cube can be solved in 52 or less moves. It was later enhanced to use 42 moves (https://www.jaapsch.net/puzzles/thistle.htm). The already mentioned "Two-Phase-Algorithm" is based on the Thistlethwaite's algorithm. And there is also a version of Thistlethwaite's algorithm called Human Thistlethwaite Algorithm.
 
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Reply to aschnell
Another very old and interesting algorithm is the Thistlethwaite's algorithm that again uses group theory. I proved that any cube can be solved in 52 or less moves. It was later enhanced to use 42 moves (https://www.jaapsch.net/puzzles/thistle.htm). The already mentioned "Two-Phase-Algorithm" is based on the Thistlethwaite's algorithm. And there is also a version of Thistlethwaite's algorithm called Human Thistlethwaite Algorithm.
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