Author: Ulrich Tuerke
Date: 07:52:54 03/03/03
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On March 03, 2003 at 10:09:46, Albert Bertilsson wrote: >On March 03, 2003 at 09:43:24, Robert Hyatt wrote: > >>On March 03, 2003 at 09:13:36, Albert Bertilsson wrote: >> >>>Hi! >>> >>>During a recent game my engine reported that a mate in 2 was found, then after >>>the next opponent move it reported that a mate in 3 was found. Does this >>>indicate a bug in the engine? >>> >>>If it matters the opponent didn't followed the PV that engine displayed mate in >>>2. But after the mate in 3 was claimed the opponent followed the PV until its >>>defeat. >>> >>>/Regards Albert >> >> >>It could be >> >>(a) a bug in hashing, where you don't adjust the mate score before storing it, >>or you >>don't adjust it when you hit it in the table. >> >>(b) your extensions make it easier to find the mate in 3 than the mate in 2 and >>you quit >>too soon. >I interpret your answer as this should not happen if the engine has no bugs and >no extensions. Since Sharper doesn't have any extensions it would be (a) then... >alhtough I can't see how this could happen. I think that this can happen without extensions, too. It's a consequence of alpha-beta. Often some move of ply n+1 already suffices to refute the preceeding move of ply n, instead of the checking move leading to the mate. It's rather a matter of move ordering. It may for instance help a bit in some cases to prefer checking moves when ordering moves. Uli > >Hmm... hope I can find anything in those .cpp files... =) > >/Regards Albert
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