Author: Uri Blass
Date: 12:09:35 03/18/03
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On March 18, 2003 at 14:37:19, Albert Bertilsson wrote: >Hi! > >I just want to publish my findings with WAC and Sharper, as I've written >previously Sharper managed a bad 195 out of 300 in WAC. > >Running test with the 105 failed positions gave this: > >Adding check extensions 69 of 105 solved, great! But adding check extensions >really lowers the BF because a lot of extending is done on a single meaningless >check. In Sharpers built in test node count rise with almost 40% =(. > >So I add code to only extend on two checks or more, and I get this: >52 out of 105 problems solved. Node count in the test rise with about 2%. > >Clearly check extension are great to have. > >But they are not so great to have most of the game when they don't manage to >give any better result. So I'm thinking maybe turn on check extensions in the >end game, and have the two check rule during the rest of the game. However, this >won't help much as many of the positions in WAC are not end game positions (at >least not by Sharpers measure). > >It all comes down to, what's best low BF or high WAC result? What do you think >about extension rules based on game phase? My opinion is that it is better to have check extensions than not to have them unless you extend too much. I think that if you want better branching factor you should improve your pruning rules(if you have no pruning rules then you have a lot to improve) and one of the advantage of good pruning is that they can allow more extensions when the tree does not explode. I think that you should test sharper in games to decide how much to extend. I think that check extension are great also for games in a lot of cases and I believe that for you depth 6 with check extensions is better than depth 7 without check extensions(I did not do the experiment and it is only a guess so you should not trust me but try it). Uri
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