Author: Dieter Buerssner
Date: 21:58:35 10/22/02
Go up one level in this thread
On October 22, 2002 at 19:38:58, Nagendra Singh Tomar wrote:
>Hi All,
> Following is the snippet of the classical PVS code
>
>/* zero windo search */
>value = -PrincipalVariation(pos, -alpha-1, -alpha, depth);
>
>/*if the zero win search fails-high do a research */
>if(value > alpha && value < beta) <=====
>{
> /* do a wide window search here */
>}
>
>My question is regarding line marked <=====
>
>Should'nt the check be (value >= alpha && value < beta)
if the value is equal alpha (or smaller alpha), it means, that the other side
had a fail high. If the value is > alpha, it means, that the other side had a
fail low (in the zero window search). Often it is a good idea, to try out some
concrete numbers. Say alpha is 10. First call is with (-11,-10). Return of -10
-> search failed high. Return of -11 -> search failed low: -(-11) = 11 > alpha.
So the answer to your question: (value > alpha) is correct.
Regards,
Dieter
This page took 0 seconds to execute
Last modified: Thu, 15 Apr 21 08:11:13 -0700
Current Computer Chess Club Forums at Talkchess. This site by Sean Mintz.