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Subject: Re: not using nullmove?

Author: Dann Corbit

Date: 17:55:13 02/17/04

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On February 17, 2004 at 12:03:03, Tord Romstad wrote:

>On February 17, 2004 at 08:19:28, martin fierz wrote:
>
>>On February 17, 2004 at 07:55:32, Tord Romstad wrote:
>>
>>>KR vs KP is a difficult one.  Does anybody have any good suggestions about
>>>how to evaluate it?  At the moment I don't have any specific code for this
>>>endgame at all, and Gothmog almost always evaluates it as a win for the rook.
>>>In reality, it is of course very often a draw.
>>
>>i'll have to think about this one too. i haven't done either KR-KP or KQ-KP;
>>KQ-KP should be rather easy as there are basically only two drawing positions;
>
>Yes.  KQ-KP is much easier, and also less important, because the probability
>of a draw is much smaller here.
>
>>KR-KP is much harder. but you should at least be able to easily identify many
>>cases where KR is clearly winning; e.g. any time the KR-side king is in the
>>square of the pawn KR is winning (with one exception: wKe2, bPd2, bKf1/f2, black
>>to move, but qsearch should catch that).
>
>This is a good start, but I think it might be more valuable to work
>from the other end:  Which positions do we know are drawn?  I guess
>the probability of a draw is big if the pawn is on the fifth rank or
>beyond and supported by the king, and the attacking king is far away.
>But this is certainly too simple to be a sure drawing rule.
>
>There is also not many clear rules to be found in Keres' "Practical
>Chess Endings" (my main endgame reference), which makes me fear that
>it is not easy to evaluate this endgame correctly.

Here's a dumb idea:

Write a program to scan a Nalimov database, but throw away everything except
won/lost/drawn/broken (needs 2 bits per reflected board position to store the
outcome state).

Then write a table.

For up to the 4 man tables, it should be really tiny and fit into ram without
any fuss.

Seems like one single program could write a recognizer for anything [for which a
Nalimov or Edwards or Thompson EGTB exists].




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