Author: Robert Hyatt
Date: 11:43:45 10/21/03
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On October 21, 2003 at 11:53:02, Tord Romstad wrote: >I don't run my engine through WAC very often, but before releasing a new >version (which I will do within a couple of days) I run the whole suite as >a sanity test. This time, the following position made me worried: > >[D]8/8/2Kp4/3P1B2/2P2k2/5p2/8/8 w - - bm Bc8; id "WAC146"; > >Previously, my program had no problems with this position. The new >version, which is the first one to include tablebase support, prefers >Bd3 instead of Bc8. At ply 21, the score is +12 for white. When I >disable tablebases, the program plays Bc8. > >Does Bd3 also win, or should I look for yet another bug? Bd3 is a second solution. It has been in my version of the test since I first found this myself, years ago. > >One of the hardest positions in WAC for my engine is number 163: > >[D]5rk1/2p4p/2p4r/3P4/4p1b1/1Q2NqPp/PP3P1K/R4R2 b - - bm Qg2+; id "WAC163"; > >On a Pentium IV 2.4 GHz, I need 11 plies and 1m53s to find the winning move. >The problem is to find the line 1... Qg2+ 2. Nxg2 hxg2+ 3. Kxg2 Bf3+ 4. Qxf3 >exf3+ 5. Kg1 Rf5! followed by Rfh5. Without nullmove pruning, this position >is solved within a few seconds. > >This is rather annoying, as I have lost more games than I would like on >the ICC because of missing similar tactics. Are there any inexpensive >tricks to help me solve this kind of positions more quickly? I pick this up at depth=9, time = 2 seconds (using one cpu on my dual 2.8 xeon box). All I can guess is that I do extensions a bit differently, somehow, or the adaptive null-move R=3~2 idea helps a bit. > >Tord
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