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max number of pseudo legal move

Posted: Sun Jun 09, 2019 3:14 pm
by xr_a_y
is there a worst position than this one

[d] 3Q4/1Q4Q1/4Q3/2Q4R/Q4Q2/3Q4/1Q4Rp/1K1BBNNk w - - 0 1

218 pseudo legal moves ?

Re: max number of pseudo legal move

Posted: Sun Jun 09, 2019 4:58 pm
by chrisw
xr_a_y wrote:
Sun Jun 09, 2019 3:14 pm
is there a worst position than this one

[d] 3Q4/1Q4Q1/4Q3/2Q4R/Q4Q2/3Q4/1Q4Rp/1K1BBNNk w - - 0 1

218 pseudo legal moves ?
I have this comment in chess source:

// max width found so far in testing is 100
#define MAXWIDTH_FULLMOVELIST 128

that would have been counting every pseudo_move_generator count in search, saving the largest, and leaving it overnight or something. I forget.

Re: max number of pseudo legal move

Posted: Sun Jun 09, 2019 5:09 pm
by xr_a_y
Based on my original message, you are taking some risks ...

Re: max number of pseudo legal move

Posted: Sun Jun 09, 2019 5:11 pm
by konsolas
Is that position even reachable from the start?

Re: max number of pseudo legal move

Posted: Sun Jun 09, 2019 5:14 pm
by xr_a_y
konsolas wrote:
Sun Jun 09, 2019 5:11 pm
Is that position even reachable from the start?
That's a good question ! Do we have "solvers" for this kind of thing ?

Re: max number of pseudo legal move

Posted: Sun Jun 09, 2019 5:53 pm
by Roland Chastain
xr_a_y wrote:
Sun Jun 09, 2019 5:14 pm
konsolas wrote:
Sun Jun 09, 2019 5:11 pm
Is that position even reachable from the start?
That's a good question ! Do we have "solvers" for this kind of thing ?
I have never used it, but if I understand correctly it's the kind of thing that Natch can do.

Re: max number of pseudo legal move

Posted: Sun Jun 09, 2019 6:13 pm
by konsolas
Even so, the proof game for a position like this would be hundreds of moves and almost certainly beyond the capabilities of a brute force search.

Re: max number of pseudo legal move

Posted: Sun Jun 09, 2019 7:54 pm
by xr_a_y
Reachable or not this is 218 moves. But is Minic, I used to set max moves to 512 ... why not 256 ? I cannot remember ...

Re: max number of pseudo legal move

Posted: Sun Jun 09, 2019 8:14 pm
by AlvaroBegue
This is not even hard. I have no experience constructing proof games, and I succeeded after a few minutes:

Re: max number of pseudo legal move

Posted: Sun Jun 09, 2019 8:28 pm
by xr_a_y
AlvaroBegue wrote:
Sun Jun 09, 2019 8:14 pm
This is not even hard. I have no experience constructing proof games, and I succeeded after a few minutes:
Great, so 256 is needed. Why did i use 512 before? Still a mistery...