Author: Angrim
Date: 11:21:18 10/09/01
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On October 09, 2001 at 13:01:13, Uri Blass wrote: >[D]8/1P6/8/5k2/2K4p/7r/1r4p1/6R1 b - - 0 61 > >This position is from the game Tao-Deep Junior7 in the last WMCCC > >Chest need some hours on p200 to see mate in 10(I used chest by the way that was >explained by paul some days ago > >see http://www.icdchess.com/forums/1/message.shtml?191857 > >Solution:61...Rg3 62.Kd4 h3 63.Kd5 h2 64.b8Q Rxb8 65.Re1 Rd3+ 66.Kc4 h1Q 67.Re5+ >Kxe5 68.Kxd3 Qd1+ 69.Kc3 Rb3+ 70.Kc4 Qc2# > >15961 seconds,292,407,791 nodes > >In the game Deep Junior7 missed the right move(Rg3) but it did not help Tao that >resigned after Rxb7. > >How much time does your program need to see mate in 10 with the full 5 piece >tablebases and without tablebases? > >Uri Well, I don't have tablebases for standard chess, so just results without tables. This is the sort of mate that pn^2 search has the most trouble with, since not only are the winning moves not forcing moves, but there are lots and LOTS of forcing moves that don't win. It will work out every possible series of pointless checks before it thinks even 3 ply deep down a non-forcing line like Rg3.. after about 1/2 hour it is working on lines that have a single non-forcing move in them, and usually a huge series of forcing moves. On the other hand, my minmax searcher(which has piece values + mobility only) found the right move at ply 2 and never changed its mind. Guess Junior was too smart for its own good in that position. Angrim
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