Author: leonid
Date: 09:58:22 02/03/01
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On February 03, 2001 at 11:41:18, Paul wrote: >On February 03, 2001 at 10:38:26, leonid wrote: > >>On February 03, 2001 at 09:10:01, Paul wrote: >> >>>Mine says a Mate in 11 :) >>> >>>00:21 BM11 08 1... Bxg5+ 2. Rxg5 Bxg5+ 3. Rxg5 Bxg5+ 4. Bhxg5 Bxg5+ 5. Bxg5 >>>Bxg5+ 6. Rxg5 Ng4+ 7. Rxg4 Qf4+ 8. Nhxf4 Qxf4+ 9. Nxf4 Nxf4+ 10. Qg6 Rh5+ 11. >>>Qxh5 Rxh5# >> >>It is likely that in 11 moves it is the quickest solution that my program can >>find through selective search. It find in 10 moves as well but it take much >>longer time. The most probable that solution is even in much lower level. >>Shortest mate I don't know for this moment. > >So your selective search also finds a Mate in 10 if you let it 'think' longer? >Do I understand that correctly? I am not sure if I can respond correctly to your question. For now I have some almost fixed four versions of selective search. Usually I use only default 4 levels. One of them find in 11 moves and quickly. But when I go to 10 moves my program can find the mate only with last and longest selective search. >Sometimes mine also does that, but not here. The funny thing was that Pretz >announced a Mate in 12 after 21 seconds, but when it played the line out from >hash after ~50 seconds it found a better move somewhere along the way and >finished in 11 moves :) So there is something strange going on in my hashtable; >but I'm afraid that if I remove the bug, it won't find the mates this fast >anymore, ha! ;) For hash I can say nothing. I still never installed it. I wait for my next computer to do this and probably I became too lazy as well. What I can say you for sure is that very often search by "lighter" selective search in bigger number of moves give better (shorter) time. In few occasions it is not so. What kind of different search you have for mate? Only if this is not the state secret. In mine (I went through huge number of possible selective search versions) and left for now in program (part that search for mate) very simple variation of selective search. All difference between all those version is that they make complet search for different number of plys before going into real selective search. Before I had, for instance, one version that was seeing if certain move affect enemy "vital lines" when making its search. Beyond selective search I have one brute force as well. >So I admit that in the line above I cheated a little, coz it originally said >BM12, I changed that by hand to BM11 (Black Mates in 11) ... yes, I'm ashamed :) No reason to be ashamed. Mine could not see in other position when your found in few moves sooner. Difference between all possible variations of mate searchers is that one will be good in some situations when the next in others. What version of selective search is the most valuable could be found only through long statistics. Not at all by solving fantasy positions like mine. Similar positions are very good for fun but even more for cleaning all kind of bugs. After what you write, I can see that your is rock solid. Many programs (could be as far as 50%) can suffer from different allergy reaction and even prematurely die in similar situations. Ciao, amico! Leonid. >ciao!, >:Paul
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