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Subject: Re: Bug in CHEST - bugfix available

Author: Dann Corbit

Date: 11:18:50 05/07/02

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On May 05, 2002 at 13:55:00, Heiner Marxen wrote:

>On April 28, 2002 at 22:00:22, Heiner Marxen wrote:
>
>>On April 28, 2002 at 18:18:38, Heiner Marxen wrote:
>>
>>>On April 28, 2002 at 08:00:15, Vincent Vega wrote:
>>>
>>>>Simplified position to show the bug:
>>>>[D]8/8/8/8/8/8/4KP2/R1Qn3k w - - 0 1
>>>>
>>>>This is a mate in 2 (1. Qxd1+).
>>>>
>>>>But CHEST says:
>>>>
>>>>CHEST version 3.19, 18-Dec-1999
>>>>Input file: 'xx'
>>>>Reading job:
>>>>#	xx
>>>>W:  Ke2 Qc1 Ra1 Pf2 (4)
>>>>B:  Kh1 Nd1 (2)
>>>>FEN: 8/8/8/8/8/8/4KP2/R1Qn3k w - -
>>>>analysing (mate in 2 moves):
>>>>No solution in 2 moves.
>>>>refu  1: Qxd1+   --      [  1-]   M2: move
>>>>refu  2: Qc6+    --      [  1-]   M2: move
>>>>refu  3: Qh6+    Kg1     [  1-]
>>>>refu  4: f3      --      [  1-]   M2: move
>>>>refu  5: f4      --      [  1-]   M2: move
>>>>refu  6: Rb1     --      [  1-]   M2: move
>>>>refu  7: Ra2     --      [  1-]   M2: move
>>>>refu  8: Ra3     --      [  1-]   M2: move
>>>>refu  9: Ra4     --      [  1-]   M2: move
>>>>refu 10: Ra5     --      [  1-]   M2: move
>>>>refu 11: Ra6     --      [  1-]   M2: move
>>>>refu 12: Ra7     --      [  1-]   M2: move
>>>>refu 13: Ra8     --      [  1-]   M2: move
>>>>refu 14: Qb1     --      [  1-]   M2: move
>>>>refu 15: Qc2     --      [  1-]   M2: move
>>>>refu 16: Qc3     --      [  1-]   M2: move
>>>>refu 17: Qc4     --      [  1-]   M2: move
>>>>refu 18: Qc5     --      [  1-]   M2: move
>>>>refu 19: Qc7     Kg1     [  1-]
>>>>refu 20: Qc8     --      [  1-]   M2: move
>>>>refu 21: Qd2     --      [  1-]   M2: move
>>>>refu 22: Qe3     --      [  1-]   M2: move
>>>>refu 23: Qf4     Kg1     [  1-]
>>>>refu 24: Qg5     --      [  1-]   M2: move
>>>>refu 25: Qb2     --      [  1-]   M2: move
>>>>refu 26: Qa3     --      [  1-]   M2: move
>>>>refu 27: Kd2     --      [  1-]   M2: move
>>>>refu 28: Ke1     --      [  1-]   M2: move
>>>>refu 29: Kf3     --      [  1-]   M2: move
>>>>refu 30: Kxd1    --      [  1-]   M2: move
>>>>refu 31: Kf1     Ne3+    [  1-]
>>>>refu 32: Kd3     --      [  1-]   M2: move
>>>>Time (virt) = 0.000 sec
>>>
>>>Sadly, I have to confirm this fact: this is a bug in Chest.
>>>If I specify option "-2" to suppress the "2-mate-heuristic", it finds the
>>>mate in 2:
>>>
>>> Qxd1+  Kh2    Qh1#
>>>        Kg2    Qh1#
>>>
>>>Hence, the bug is in the "mate2" module.  Since that one is a really complex
>>>one, it will take some time to track it down.
>>>When I have found it, I will report under what circumstances it does appear.
>>
>>Fortunately, I could track down this bug.
>
>[snip]
>>It is quite easy to correct this bug, and within the next week I will
>>provide a corrected source module.
>>It will be announced here, and be available through my web page.
>
>   http://www.drb.insel.de/~heiner/Chess/chest.html
>
>contains a reference to the corrected source code "mate2.c":
>
>   http://www.drb.insel.de/~heiner/Chess/mate2.c
>
>>Hopefully Dann will then provide a corrected win32 executable.
>>Since the circumstances for the bug to occur are not really very rare,
>>I'd recommend upgrading to the new version when available.
>
>I can't speak for Dann, but it would be very nice of him to offer
>an updated source package, and more importantly, a corrected binary.
>(I myself cannot compile for windows).

Everything:
ftp://cap.connx.com/pub/chess-solvers/chest/

The package in a zip:
ftp://cap.connx.com/pub/chess-solvers/chest/CHEST319.ZIP

The binary only:
ftp://cap.connx.com/pub/chess-solvers/chest/chest319.exe



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