Hi,
throughout speedsolving.com, readers can find mentions about David Gilday´s own 2-phase 3x3x3 algorithm (such as here or here). Since I haven´t found an explanation of his two-phase algorithm anywhere on speedsolving.com, I was wondering what exactly is it?
To complicate things, David (or rather his robots) seems to be also using a 2-phase algorithm based on 2-phase Kociemba´s algoritm (regardless whether being optimized for robot solving or not - but this is not a subject of this post).
So what do we know about Gilday´s algorithm? Example solve taken from here.
His phase 1 ends with at least 7 pieces being solved according to this post. If move no. 11 was R, a 2x2x3 block would be build. Move no. 11 is R2 because the last move in phase 1 is R and the first move in phase 2 is also R. Another example taken from the second link above:
Now phase 1 = moves 1-10, phase 2 = moves 11-21. So there you have it: David Gilday´s two-phase algorithm seems to be this solving process: Scrambled -> 2x2x3 block -> Solved (in at most 12 moves, see next paragraph).
Phase 1 needs at most 11 moves and phase 2 needs at least 18 moves according to this post and this analysis for a specific block. However, David says that the solution length of phase 2 is limited to 12 moves in this post so his phase 1 solution length will probably be longer than 11 moves for some scrambles.
Some other 2-phase algorithms for comparison are listed here.
throughout speedsolving.com, readers can find mentions about David Gilday´s own 2-phase 3x3x3 algorithm (such as here or here). Since I haven´t found an explanation of his two-phase algorithm anywhere on speedsolving.com, I was wondering what exactly is it?
To complicate things, David (or rather his robots) seems to be also using a 2-phase algorithm based on 2-phase Kociemba´s algoritm (regardless whether being optimized for robot solving or not - but this is not a subject of this post).
So what do we know about Gilday´s algorithm? Example solve taken from here.
His phase 1 ends with at least 7 pieces being solved according to this post. If move no. 11 was R, a 2x2x3 block would be build. Move no. 11 is R2 because the last move in phase 1 is R and the first move in phase 2 is also R. Another example taken from the second link above:
Now phase 1 = moves 1-10, phase 2 = moves 11-21. So there you have it: David Gilday´s two-phase algorithm seems to be this solving process: Scrambled -> 2x2x3 block -> Solved (in at most 12 moves, see next paragraph).
Phase 1 needs at most 11 moves and phase 2 needs at least 18 moves according to this post and this analysis for a specific block. However, David says that the solution length of phase 2 is limited to 12 moves in this post so his phase 1 solution length will probably be longer than 11 moves for some scrambles.
Some other 2-phase algorithms for comparison are listed here.
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