Author: Nobuhiro Yoshimura
Date: 15:56:38 01/12/00
Go up one level in this thread
>>>>Regards Dan Andersson >>> >>> >>>Note that this is not easy to do. Because if you give the bonus at the root, >>>it affects the score at the tips of the tree below that root move. And thanks >>>to the hash table, you can now play the move at ply=3 at the root, and the >>>root move at ply=3, and the hash table will politely include the original bonus >>>due to the way hashing is about positions, not moves. >> >>I disagree, root move penaties are fairly easy to do right. >>If coded correctly a root move bonus/penalty will not change the values >>stored in the hash except as you would expect from changeing the search window. >>The score at the leaf nodes is not affected since you should >>be adding the bonus after you have searched the move. One thing you might >>have some trouble with is that the alpha-beta bounds have to be adjusted >>to take into account the amount that you will be adding to the score. >> >>For example, with alpha=100 beta=110 and a root bonus of +50 you need >>to search with a window of 50-60 so that the returned score(after bonus) >>will be in the correct range. >>then if it returns <=50 you failed low with <=100 >>if it returns 52 then you have a new best move with score 102 >>if it returns >=60 you failed high with a score of >=110 >> >>Also have to be carefull with this around forced win/loss values, since >>if your window was +win50 to +win1 and you give a 50 point bonus to a >>move you could be searching with a window of +win1 to +win1+50 <bad thing> >>So if alpha or beta is a win/loss value don't adjust it, and if the >>returned score is a win/loss value don't add the bonus. >> >>Hope this helps, >>Angrim > > >That is a known 'fix' but it has its difficulties... What kind of difficulties do you in mind?
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