Author: Uri Blass
Date: 03:56:31 09/04/04
Go up one level in this thread
On September 03, 2004 at 19:58:55, Ross Boyd wrote:
>On September 03, 2004 at 10:25:27, Stuart Cracraft wrote:
>
>>On September 03, 2004 at 06:41:16, Ross Boyd wrote:
>>
>>>On September 03, 2004 at 00:43:27, Stuart Cracraft wrote:
>>>TRACE solves this (now) in under a second on a PIII-450. Previously, it took
>>>several minutes...
>>>
>>>I can tell you that I debugged my THREAT extension code and found Crafty's exact
>>>method was not conducive to good results (for TRACE).
>>>I extend when nullmove_score==-MATE+ply+1
>>
>>Please include the call to your search for the null move? I want to
>>see your window.
>
>No problems....
>
>null_depth = remaining_depth - R; // R=2 for me, always
>
>if( null_depth > ONE_PLY)
> nullmove_score = -search(-beta, -beta+1, null_depth - ONE_PLY);
>else
> nullmove_score = -quiesce(-beta,-beta+1);
>
>unmakenullmove();
>
>if (nullmove_score >= beta) {
> return nullmove_score; // Fail soft
>}
>
>if (nullmove_score == -CHECKMATE+ply+1) {
> hashflags |= THREAT_FLAG; // Tag it as a position with mate threats
>}
>
>// and then this code, (more or less)
>if (hashflags & THREAT_FLAG)
> remaining_depth += EXTEND_THREAT;
>
>
>Actually, since changing my search to count nullmoves as a ply increment, it
>works better with -CHECKMATE+ply+2....
>
>HTH,
>
>Ross
How much is EXTEND_THREAT for you?
At the moment I do not extend mate threats.
I checked that my tree can explode if I extend one ply for mate threat because I
also extend in most cases one ply or slightly more than it for positions when
the king is in check(slightly more than it may happen often but not always in
case of a single reply) and if a reply to check is a mate threat the program can
crash.
I can limit it to less than it but I am still afraid from explosion for the same
reason because single reply to check can be extended by almost 2 plies in some
cases that hopefully do not happen often.
Uri
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