Author: Robert Hyatt
Date: 19:28:55 05/07/01
Go up one level in this thread
On May 07, 2001 at 21:14:54, Brian Richardson wrote:
>On May 07, 2001 at 16:30:26, Robert Hyatt wrote:
>
>>On May 07, 2001 at 16:15:08, Brian Richardson wrote:
>>
>>>In general...
>>>
>>>I don't know about adding pawns to the mix (per the Crafty/Diep games), but in
>>>evaluate.c, Crafty seems toI prefer the single queen to 2 rooks, or am I missing
>>>something...
>>>
>>> else if (WhiteMajors == BlackMajors) {
>>> if (WhiteQueens && !BlackQueens) score+=BAD_TRADE>>1;
>>> else if (!WhiteQueens && BlackQueens) score-=BAD_TRADE>>1;
>>> }
>>
>>That is where I correct the score to avoid tweaking with piece values and
>>seeing nonsense moves that do bad things. This says that a queen is only
>>a little worse than two rooks. Which means that if I have a queen and a pawn,
>>vs two rooks (and ignoring everything else on the board) then the queen and pawn
>>are a little better as the two rooks will never win.
>>
>>that is nothing compared to the bonus Vincent tosses in for Q vs 2R...
>
>OK, but it looks like Crafty prefers the white queen to the 2 black rooks with
>score += BAD_TRADE (and vice versa)...or do I have it backwards?
>
>Thanks
>Brian
Think about this: I have two rooks, you have a queen. My two rooks probably
grab a significant positional bonus for open files, 7th rank, mobility, and so
forth. This would tend to grossly overinflate the advantage of two rooks for
a queen, so I scale it back by the code you gave. I have found that two rooks
for a queen and pawn to be pretty even... that forces my evaluation to agree
with this premise...
That BAD_TRADE>>1 gets adjusted from time to time... I am currently not happy
with my rook scoring as with an open file, or two rooks connected on the open
file or on the 7th, etc, the scores can get larger than I believe reasonable.
As I get that under control, the bonus you mentioned above will be scaled back
as well...
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