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Subject: Re: Caution K v KBN and lazy eval or futility

Author: Bruce Moreland

Date: 16:24:06 05/14/00

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On May 14, 2000 at 16:53:46, Brian Richardson wrote:

>Tinker's q-search lazy eval (material - max_pos_score)> beta return (like
>standing pat?), and (material + queen+pawn) <= alpha return (quasi-futility?)
>was working fairly well, until a K vs KBN endgame.  Since it was not getting to
>the eval function, the special mating code was never used and Tinker ended up
>with a 50 move draw...Now I check for opponent's pieces <= one minor and skip.
>
>This was discussed in ICCA Vol 21 # 2 (Extended Futility and Dark Thought).  I
>also have tried various regular futility, extended futility and razoring (as
>outlined in the ICCA article), but they did not seem to help, at least given
>Tinker's mix of searching algorithims.
>
>Anyone else getting "good" results with them?

Take all that stuff out and do whatever you want and you'll probably still draw
in KBN v K.

In 1980 I was studying KBN v K for some unknown reason, and I set it up on my
Chess Challenger 7, and prepared to be shown how to do it.  Haha.  50 moves
later my king was still in the center.

Things haven't gotten much better, unless you use endgame databases or have a
special function for this ending.  It's hard for a program to get you in the
corner, and once there it's hard for it to understand that it's the wrong
corner, and it needs to get you into the other corner.

bruce


bruce




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