Author: Enrique Irazoqui
Date: 02:52:57 09/04/00
Go up one level in this thread
On September 03, 2000 at 18:45:31, Uri Blass wrote:
>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
In all of the many variations I tried, this position is a mate in 12 or less.
For instance:
31. f3 $1 Bd6 32. f5 c5 (32... Bc5 33. Rg3 Be3 34. Qxe3 Qxf5 35. Rg1 h5 36.
Qh6+ Qh7 37. Rg6 c5 38. Bxg7+ Rxg7 39. e7 Rxg6 40. e8=Q+ Rg8 41. Qf6+ Qg7 42.
Qxh5#) 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
Enrique
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