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Subject: Re: Easy mate

Author: Rafael Andrist

Date: 02:31:11 09/14/03

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On September 13, 2003 at 18:20:56, Dieter Buerssner wrote:


>My TB-generator does confirm this more or less. It minimaxes the distance
> to the next pawn push or capture, and the result is: lost in 52
> (which will be set to draw, when my testing phase is finished).

The DTZ depth is 51 according to the tables I use, but maybe you just count the
depth differently. In a pawnless endgame with DTM-optimal = DTC-optimal play
with two DTC phases the sum of DTC at the beginning of each phase should equal
DTM. Similar for DTZ, but more difficult to check.

I'm sure you aware of this, but note that setting DTZ>50 to a draw after the
generation process is not very useful as you miss the biggest number of draws,
because they have DTZ<=50.


>I guess, that in similar positions also the other way around my be possible:
>white goes for a longer mate, but can force a pawn-push/capture faster by this.

Here, Black can even allow a pawn push at move 7 (see my other post) and still
draw in the next phase.

>BTW. Generating the knnkp database took 15 minutes and used less than 40 MB of
>RAM. When I wrote up a bit more code, I can show the line.

This is very impressive! You must have found an interesting trick to generate
the database in 15 minutes only.

I'm basically using the Nalimov code, with modifications by Marc Bourzutschky.
This has the advantage of compatibility. With some minor changes (pawn
push/capture recognition) all engines will be able to use the database.

regards
Rafael B. Andrist



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