bugXBoard - Bugs: bug #48321, Strange "adjudication:...

 
 

bug #48321: Strange "adjudication: Checkmate but bare king"

Submitter:  None
Submitted:  Sun 26 Jun 2016 11:39:51 PM UTC
   
 
Category:  XBoard (X11) Severity:  3 - Normal
Item Group:  None Status:  Invalid
Assigned to:  None Open/Closed:  Closed
Release:  None
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Sat 15 May 2021 05:42:36 AM UTC, comment #3: 

H.G. explained a bit more in email at the time:

"Normally XBoard corrects all wins for a side with a bare King to a draw, and then appends this "but bare king" phrase to the result message. This is mainly meant for wins by forfeit (e.g. flagging), as in normal chess it should not be possible to checkmate when you have only a king. (There was a problem in variant atomic, where it actually quite usual that a king is the only piece left after you explode the opponent king with your last pieces, but this was fixed in 4.9.0.)"

The above produces confusing results in a case like this one, where black won by checkmate, but (it seems) an engine bug caused the engine to send xboard a message saying that white won by checkmate.  Correcting for engine bugs is a bit above and beyond the requirements for xboard, though it does try to do so sometimes.

Anyway, I am closing this as an engine bug, not xboard bug.


Tim Mann <mann>
Group administrator
Mon 27 Jun 2016 03:05:23 AM UTC, comment #2: 

I could be missing a bug in the code that prints this message, but from reading it, it looks to me like the engine that lost (White) tried to claim a win (that may just be a minor bug in the message the engine issued).  This code would then catch that you can't win with a bare king and adjudicate a draw.

Offhand it seems like it would be a good idea to run our own mate detector (prior to the weaker bare king detection) and make the stronger correction of giving the right engine the win.  I.e., adjudicate the win for Black.

Tim Mann <mann>
Group administrator
Sun 26 Jun 2016 11:48:17 PM UTC, comment #1: 

XBoard version was 4.9.0 on Arch Linux

Philipp Claßen <phcl>
Sun 26 Jun 2016 11:39:51 PM UTC, original submission:  

In the attached game, XBoard sets the score to remis although it looks like a regular check mate. Seems like a bug.

84. ... Qh2# seems like a normal checkmate and should result in a black win.

Anonymous

 

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Attached Files
file #37590:  xboard_changes_mate_to_draw.pgn added by None (4KiB - application/x-chess-pgn)

 

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    Follow 4 latest changes.

    Date Changed by Updated Field Previous Value => Replaced by
    2021-05-15 mann StatusNone Invalid
        Open/ClosedOpen Closed
    2016-06-26 phcl Carbon-Copy- Added phcl
    2016-06-26 None Attached File- Added xboard_changes_mate_to_draw.pgn, #37590

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