Author: Uri Blass
Date: 12:33:09 03/29/01
Go up one level in this thread
On March 29, 2001 at 14:41:58, Chessfun wrote: >On March 29, 2001 at 14:08:06, Christophe Theron wrote: > >>On March 29, 2001 at 08:50:14, José Antônio Fabiano Mendes wrote: >> >>> An interesting miniature by a Russian composer(sorry,I can't remember >>> his name) I came across the other day: >>> [D]2N5/8/8/8/7p/8/7B/4K2k w >>> The _only_ winning move is 1.Bb8!! [mate in 34] >> >> >>Do I have a bug? >> >>Chess Tiger 14.0 and Gambit Tiger 2.0 both announce mate in 28 (that means they >>think it is a mate in 29 starting from your position). >> >>The line is: >> >>00:32:36.2 Mate in 28 20 354603928 Bb8 Kg2 Ne7 h3 Bh2 Kf3 Ng6 Kg4 Kf2 Kf5 Nf4 >>Ke4 Kg3 Kd4 Kxh3 >> >> >>I do not have all the tablebases installed, and it is why Tiger needed half an >>hour on my K6-2 450 to find the mate (24Mb hash). >> >> >> Christophe > > >ChessTiger 14.0 and Gambit 2.0 with all 3, 4 and 5 men bases >call it mate in 34 instantly. > >Tablebases turned _OFF_ >I waited till my Nodes were over 354603928 >Gambit 2.0. Thunderbird @945 mhz with 96 mb hash. > >; 00:00:00.1 2. Score: 0.00 depth: 13 Be5 Kg2 Ne7 h3 Ng6 h2 Bxh2 Kxh2 >; 00:00:00.8 2. Score: 0.11 depth: 14 Be5 h3 Kf2 h2 Kg3 Kg1 Bd4+ Kh1 Bf6 >Kg1 Bd4+ >; 00:00:00.8 2. Score: 0.90 depth: 14 Bb8 >; 00:00:01.0 2. Score: 6.54 depth: 14 Bb8 Kg2 Ne7 h3 Bh2 Kf3 Nf5 Ke4 Nh4 >Ke3 Bg3 Kd3 Kf2 Ke4 >; 00:00:03.6 2. Score: 7.44 depth: 15 Bb8 >; 00:00:04.3 2. Score: 7.88 depth: 15 Bb8 h3 Kf2 h2 Kg3 Kg1 Ba7+ Kh1 Nb6 >Kg1 Nc4+ Kh1 Ne3 Kg1 Ng4+ Kh1 Bb8 Kg1 Nxh2 >; 00:00:06.4 2. Score: 7.88 depth: 16 Bb8 h3 Kf2 h2 Kg3 Kg1 Ba7+ Kh1 Nb6 >Kg1 Nc4+ Kh1 Ne3 Kg1 Ng4+ Kh1 Bb8 Kg1 Nxh2 >; 00:00:09.4 2. Score: 8.32 depth: 17 Bb8 h3 Kf2 h2 Kg3 Kg1 Ba7+ Kh1 Nb6 >Kg1 Nc4+ Kh1 Ne3 Kg1 Ng4+ Kh1 Bb8 Kg1 Nxh2 >; 00:00:10.4 2. Score: 8.32 depth: 18 Bb8 h3 Kf2 h2 Kg3 Kg1 Ba7+ Kh1 Nb6 >Kg1 Nc4+ Kh1 Ne3 Kg1 Ng4+ Kh1 Bb8 Kg1 Nxh2 >; 00:00:14.9 2. Score: 8.48 depth: 19 Bb8 h3 Kf2 h2 Kg3 Kg1 Ba7+ Kh1 Nb6 >Kg1 Nc4+ Kh1 Ne3 Kg1 Ng4+ Kh1 Bb8 Kg1 Nxh2 >; 00:00:21.1 2. Score: 8.60 depth: 20 Bb8 h3 Kf2 h2 Kg3 Kg1 Ba7+ Kh1 Nb6 >Kg1 Nc4+ Kh1 Ne3 Kg1 Ng4+ Kh1 Bb8 Kg1 Nxh2 >; 00:05:45.0 2. Score: 8.72 depth: 21 Bb8 h3 Kf2 h2 Kg3 Kg1 Ba7+ Kh1 Nb6 >Kg1 Nc4+ Kh1 Ne3 Kg1 Ng4+ Kf1 Nxh2+ Ke1 Bf2+ >; 00:05:56.2 2. Score: 8.72 depth: 22 Bb8 h3 Kf2 h2 Kg3 Kg1 Ba7+ Kh1 Nb6 >Kg1 Nc4+ Kh1 Ne3 Kg1 Ng4+ Kf1 Nxh2+ Ke2 Ng4 >; 00:10:59.3 2. Score: 8.80 depth: 23 Bb8 h3 Kf2 h2 Kg3 Kg1 Ba7+ Kh1 Nb6 >Kg1 Nc4+ Kh1 Ne3 Kg1 Ng4+ Kf1 Nxh2+ Ke2 Nf3 >; 00:12:27.3 2. Score: 8.80 depth: 24 Bb8 h3 Kf2 h2 Kg3 Kg1 Ba7+ Kh1 Nb6 >Kg1 Nc4+ Kh1 Ne3 Kg1 Ng4+ Kf1 Nxh2+ Ke2 Nf3 >; 00:15:23.2 2. Score: 8.80 depth: 25 Bb8 h3 Kf2 h2 Kg3 Kg1 Ba7+ Kh1 Nb6 >Kg1 Nc4+ Kh1 Ne3 Kg1 Ng4+ Kf1 Nxh2+ Ke2 Nf3 > >; Analysis completed > >It could be your have odd tablebases, I have seen that >type of behavior from most engines when they are missing >a critical tablebase. > >Sarah. It still seems to be a bug if a program say mate in 28 when there is only mate in 34. The only other explanation that I can think off is hash tables collision when the computer assumes that 2 different positions are the same but with 24Mb hash tables and 64 bits signature and 354603928 nodes the chances for this problem is very small. Uri
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