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Subject: Re: Move ordering ideas

Author: leonid

Date: 06:12:17 03/08/01

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On March 08, 2001 at 05:08:03, Matt McKnight wrote:

>oops, messed up that last post...
>
>   I've been toying with some move ordering ideas, and I would like to hear some
>feedback on them.
>
>   First idea:
>     Inspired by the killers list, I tried keeping a list of two moves per ply
>that seemed to be bad ideas, (score < alpha) and using that to sort those moves
>in the future to the end of the list.  This seems to give me a small gain.  Is
>this idea good, or will it cost me in some positions?


I could be lost in official terms but I for sure save two moves per ply. Brute
force search goes at very acceptable speed because of this. In my program these
two moves I name as best "active" and "passive" moves. Best active move - move
between checking moves and moves that give material advantage. Passive move -
all others. In each ply, best active move is put at the head of moves line
before start searching for that ply. Second "best passif move" is used for
aligning all passive moves only if best move was not already found between
"actives".

Leonid.


>   Second idea:
>     Along with the history heuristic, how about sorting moves by the
>positional gain they make?  For instance:
>             score += piece_eval[to] - piece_eval[from];
>
>this also seems to help a little.  Again, is it helping or not?
>
>Also, are these ideas dumb and old?
>
>Matt



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