max number of pseudo legal move

Discussion of chess software programming and technical issues.

Moderators: hgm, Harvey Williamson, bob

Forum rules
This textbox is used to restore diagrams posted with the [d] tag before the upgrade.
User avatar
xr_a_y
Posts: 729
Joined: Sat Nov 25, 2017 1:28 pm
Location: France

max number of pseudo legal move

Post by xr_a_y » 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 ?

chrisw
Posts: 2000
Joined: Tue Apr 03, 2012 2:28 pm

Re: max number of pseudo legal move

Post by chrisw » Sun Jun 09, 2019 4:58 pm

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.

User avatar
xr_a_y
Posts: 729
Joined: Sat Nov 25, 2017 1:28 pm
Location: France

Re: max number of pseudo legal move

Post by xr_a_y » Sun Jun 09, 2019 5:09 pm

Based on my original message, you are taking some risks ...

konsolas
Posts: 182
Joined: Sun Jun 12, 2016 3:44 pm
Location: London
Full name: Vincent
Contact:

Re: max number of pseudo legal move

Post by konsolas » Sun Jun 09, 2019 5:11 pm

Is that position even reachable from the start?

User avatar
xr_a_y
Posts: 729
Joined: Sat Nov 25, 2017 1:28 pm
Location: France

Re: max number of pseudo legal move

Post by xr_a_y » 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 ?

User avatar
Roland Chastain
Posts: 201
Joined: Sat Jun 08, 2013 8:07 am
Location: France
Full name: Roland Chastain
Contact:

Re: max number of pseudo legal move

Post by Roland Chastain » Sun Jun 09, 2019 5:53 pm

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.

konsolas
Posts: 182
Joined: Sun Jun 12, 2016 3:44 pm
Location: London
Full name: Vincent
Contact:

Re: max number of pseudo legal move

Post by konsolas » Sun Jun 09, 2019 6:13 pm

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.

User avatar
xr_a_y
Posts: 729
Joined: Sat Nov 25, 2017 1:28 pm
Location: France

Re: max number of pseudo legal move

Post by xr_a_y » Sun Jun 09, 2019 7:54 pm

Reachable or not this is 218 moves. But is Minic, I used to set max moves to 512 ... why not 256 ? I cannot remember ...

AlvaroBegue
Posts: 919
Joined: Tue Mar 09, 2010 2:46 pm
Location: New York
Full name: Álvaro Begué (RuyDos)

Re: max number of pseudo legal move

Post by AlvaroBegue » 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:

User avatar
xr_a_y
Posts: 729
Joined: Sat Nov 25, 2017 1:28 pm
Location: France

Re: max number of pseudo legal move

Post by xr_a_y » Sun Jun 09, 2019 8:28 pm

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...

Post Reply