Author: Uri Blass
Date: 15:45:31 09/03/00
Go up one level in this thread
On September 03, 2000 at 16:50:04, Uri Blass wrote:
>On September 03, 2000 at 16:44:12, Enrique Irazoqui wrote:
>
>>On September 03, 2000 at 16:20:24, Uri Blass wrote:
>>
>>>On September 03, 2000 at 14:59:52, Enrique Irazoqui wrote:
>>>
>>>>[D]5qrk/p1p1b1rp/4P2Q/1p6/5P2/8/P4P1P/B5RK w - b6 0 31
>>>>
>>>>Is there a program that can see a forced mate in this position? The main line is
>>>>in the PGN score below, but 31... Bd6 offers more resistance. Most programs have
>>>>trouble finding the first move, f3, let alone the mate line.
>>>>
>>>>Enrique
>>>>
>>>>[Event "corr"]
>>>>[Site "?"]
>>>>[Date "1879.??.??"]
>>>>[Round "?"]
>>>>[White "Chigorin, Mikhail"]
>>>>[Black "Yakubovich"]
>>>>[Result "1-0"]
>>>>[SetUp "1"]
>>>>[FEN "5qrk/p1p1b1rp/4P2Q/1p6/5P2/8/P4P1P/B5RK w - b6 0 31"]
>>>>[PlyCount "11"]
>>>>[EventDate "1879.??.??"]
>>>>[Source "ChessBase"]
>>>>
>>>>31. f3 $1 c5 (31... Bd6 32. f5 Qe7 {(mate in 38, Fritz 6a)}) 32. f5 b4 33. Rg3
>>>>c4 34. Qxh7+ $1 Kxh7 35. Rh3+ Bh4 36. Rxh4# 1-0
>>>
>>>The mate in 38 is probably a bug in fritz.
>>>
>>>I believe that tablebases are not relevant here and that Fritz does not search
>>>more than 70 plies forward in all the lines so it cannot see mate in 38.
>>>
>>>I also do not believe that hash tables can prove mate in 37(it is possible that
>>>Fritz searches 40 plies forward and it remembers that the final position is mate
>>>in 18 so the root position is mate in 38 but it seems more logical to me that
>>>this long mate score is a bug).
>>>
>>>I gave the position for chessmaster(ss=10).
>>>
>>>I never saw chessmaster gives these strange mate scores.
>>>
>>>Chessmaster shows main line that begins with 1.f3 Bd6 with 5.95 pawns for white
>>>after 19 minutes and 14 seconds on pIII450(The score is going up every iteration
>>>and maybe it can find the mate in the next iteration).
>>>
>>>Uri
>>
>>I'm trying with F6b, Goliath light and CM6k. The best line I got so far is a
>>mate in 12: 31. f3 Bd6 32. f5 c5 33. Rg4 Bf4 34. Qxf4 Qd8 35. Rg1 c4 36. Bd4 Qb6
>>37.
>>Rxg7 Rxg7 38. Bxg7+ Kg8 39. Bh6 Qd8 40. Qg3+ Qg5 41. Qxg5+ Kh8 42. Qd8# 1-0
>>
>>But I am forcing the moves, so I can't be sure that there is not a better line.
>>
>>Enrique
>
>Main line of chessmaster at depth 4/13 begins with 31.f3 Bd6 32.f5 b4 but the
>move after 32.f5 is always changing and at depth 3/12 it was c5.
>
>Chessmaster did not finish iteration 4/13 after 50 minutes.
At depth 5/14 after more than 2 hours chessmaster has only evaluation of more
than +7 and the main line begins again with 31.f3 Bd6 32.f5 c5.
I see that this problem is too hard for chessmaster and it seems that the only
way to prove mate is by forcing moves but there are many lines to analyze.
Example: one line is 31.f3 a6 32.f5 Bc5 and now chessmaster needs some minutes
to see that Rg3 is mate in 12.
Uri
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