Author: Jan Pernicka
Date: 04:17:55 05/02/00
Go up one level in this thread
On May 02, 2000 at 06:26:34, Michael Neish wrote:
>
>Hello,
>
>I wonder whether anyone could help me, or offer any suggestions as to the
>following little problem.
>
>The program I'm writing needs two ply to see what I think should take only one
>ply.
>
>In the position below White wins material by the blindingly obvious Bg5.
>
>[D]6k1/pp1nrppp/5rb1/P2P4/5BP1/5P2/4BK1P/R3R3 b - -
>
>However, if I set my program to look only one ply deep, it doesn't see this
>move, and prefers Bb5. At two ply, though, it sees it all right. I think one
>ply should be enough, as the Qsearch ought to take care of the ensuing
>exchanges. Indeed, other programs I have tried manage to find it easily enough
>in one ply.
>This might be a trivial position, but if it's taking longer than it should to
>see these tactics then I could be wasting plies in my search.
>
>By the way, in case anyone asks, I'm not doing anything unusual in Qsearch. I
>call Eval() first, return if it fails high, otherwise set alpha to the Eval()
>score if it's greater than alpha, and then search through the available
>captures.
>
>Thanks for your help.
>
>Mike.
Hi Mike,
when you search only 1 ply it's white's move - and then you start Qsearch
(when black is to move) - and so after your Bg5 black is satisfied with
his present score because whatever capture he can do will be refuted
by white's capturing his rook.
On the other hand - most of chess programs are clever enough to search
1 ply deeper if some special happens (as threat :) instead of starting
Qsearch() immediately...
Have a nice day
Jan
PS: Bb5 seems for your program to be more "positional" than Bg5...:)
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