Author: blass uri
Date: 21:17:28 05/02/00
Go up one level in this thread
On May 02, 2000 at 07:38:08, Ed Schröder wrote: >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. > >Rebel gives a bonus of 1.00 in eval for Bg5 assuming one of those rooks >get lost. A higher bonus is quite risky as the opponent often has an >escape. The effect in search is minor. It was effective in the days of >programs running at 5 Mhz hiting 5-6 plies only. Nowadays I would not >spend time on such (processor) time consuming cases. > >Ed I do not understand why not. If there is a long line when the final position is one of these cases you can have a better evaluation. Usually long lines are not forced so the effect may be better positional moves and not tactics. Uri
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