Author: Stuart Cracraft
Date: 08:33:12 09/01/04
Go up one level in this thread
On September 01, 2004 at 05:28:55, Tord Romstad wrote:
>On September 01, 2004 at 05:00:32, Chris Welty wrote:
>
>>What is a Botvinnik-Markoff extension?
>
>An extension which is triggered every time the null move fails for the same
>reason twice in a row. Whenever the null move fails low (you may want to
>do it only when it fails low by some margin), you set ThreatMove[Ply] to
>the move that refuted the null move. The code for the actual extension
>is something similar to this (should be located directly after the null
>move search in your code):
>
> if((null move failed low) &&
> (ThreatMove[Ply]==ThreatMove[Ply-2] ||
> (ThreatMove[Ply] and ThreatMove[Ply-2] captures the same piece)))
> Extend
>Tord
Tord,
By fail low I assume you mean that simply value from null move
search simply didn't fail high?
All I do for null is
if (okay to do null) {
makenullmove;
value = null() with reduced depth
if (value >= beta) { unmakenullmove; return(value); }
}
/// so I know I have to put something here, but I have no move
/// that refutes null move search above. Do you mean that ThreatMove[...]
/// should be set to the best move found by the reduced search at its
/// first ply?
Thanks,
Stuart
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