# Computer Chess Club Archives

## Messages

### Subject: Re: not using nullmove?

Author: martin fierz

Date: 01:50:16 02/17/04

Go up one level in this thread

```On February 16, 2004 at 18:14:45, Dieter Buerssner wrote:

>On February 16, 2004 at 10:24:26, martin fierz wrote:
>
>>i think i saw KRP-KR once, muse on the weak side, clear draw. gothmog thought it
>>was about 1.5 pawns ahead IIRC. a simple but good rule for this one is: if the
>>king of the defending side is anywhere on the pawn's path to a queen, it's a
>>draw - i don't return a draw there, but something like -0.5 pawns for the
>>defender - after all, you still have small chances against a weak opponent. but
>>perhaps this was in a game against frenzee - i hope i haven't mixed things up...
>
>Martin, can you please elaborate on your rule "anywhere on the pawn's path to a
>queen". I don't get it. I believe I understand basic draw and won positions in
>KRPKR (from text books). But I am not able to understand your rule.
>
>Regards,
>Dieter

hi dieter

there is more to KRP-KR than this simple rule of course. but for it's
simplicity, it works pretty well. i'm not saying you should use it. you have a
strong engine with a good eval, and i expect your KRP-KR eval to be much better
than this. but anybody who has no special eval for KRP-KR should find the
following rule useful:

take your pawn. produce the "crowning path", which is just all squares in front
of the pawn. e.g. white pawn on e4, crowning path is e5,e6,e7,e8. if the black
king is on any of these squares, evaluate the position as slightly better for
white only. if not, evaluate it as very good for white.
probably you can add left(crowningpath) and right(crowningpath) to the drawing
zone. i.e. you say if the white pawn is on e4 and the black king anywhere within
the rectangle d5-f5-f8-d8 you evaluate as a near draw.

of course there are drawing positions with the king outside this zone, and lost
positions within. but it's much better than nothing and *very* simply specially
if you have bitboards :-)

cheers
martin

```