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Subject: Re: impact of early queen exchange on performance

Author: Ricardo Gibert

Date: 13:13:17 10/09/02

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On October 09, 2002 at 13:28:50, Mike S. wrote:

>Percentages, based on a large comp-comp database:
>
>Engine          | #Games   total  W    B  | total eQE* W/eQE   B/eQE
>-------------------------------------------------------------------
>Fritz 7         |  784      69%  72%  65% | 59% (#57)   53%     67%
>Chess Tiger 14  |  850      66%  71%  62% | 72% (#71)   73%     71%
>Shredder 6/-P.  |  743      61%  65%  57% | 58% (#58)   63%     53%
>Junior 7        |  799      55%  58%  53% | 41% (#60)   25% !   56%
>
>*) "eQE" = early queen exchange (within the first 10 moves)


None of the engines seem to fair too badly as Black when there is an exchange of
queens. The picture is different as white for Fritz and Junior. It seems the
statistics are sensitive to color!

I suspect engine performance in the ending is sensitive to opening repertoire
used, e.g. gambits do poorly after an exchange of queens, so by not playing
gambits an engine can improve their ending stats. Or maybe Fritz and Junior are
better middlegame defenders, i.e. they are able to limp into a bad endings
instead of getting mated in the middlegame. Many explanations are possible.

It would be better to measure endgame performance using some type of test set. A
while back someone tested various engines with various rook endings. Very
interesting. I think that sort thing is the way to go if you want to test
endgame performance.


>
>Fritz 7's white percentage after an early exchange of the queens was 53% only,
>compared to it's general white average of 72%! Remarkable also Tiger 14's result
>with black: Much better (71% to 62%) without queens. Desastrous was Junior 7's
>result with white when the queens were off the board soon: only 25% (in 30 games
>of that kind).
>
>It looks as if the engines each are very different, in how they depend on having
>the queen... with Shredder 6/-Paderborn showing the smallest impact.
>
>For games with Black against Fritz 7 or Junior 7 (and probably against others
>too for which I didn't search the statistics), it could be promising to have an
>opening book which favours eQE variants... But that of course must not have
>"wholes" in other (more common) lines, so it can't be done by simply generate an
>opening tree based on an eQE games database only.
>
>Regards,
>M.Scheidl



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