Author: Vladimir Medvedev
Date: 03:17:20 02/05/03
My engine uses the following extensions:
* mate threat extension ( = 32/16 ply )
* single move extension ( = 24/16 ply )
* pawn on 7th extension ( = 16/16 ply )
* check extension ( = 12/16 ply )
* recapture extension ( = 12/16 ply )
At each node only one (max) extension can be applied.
I tried two possible variants of extensions rule:
Variant 1):
AlphaBeta(...)
{
...
if( remain_depth < 4*HALFMOVE ){
// analyze extensions conditions and apply extensions here
// this is done for nodes near qsearch margin
}
...
}
Variant 2):
AlphaBeta(...)
{
...
if( current_ply < 2*current_iteration ){
// analyze extensions conditions and apply extensions here
// this is done for nodes not very far from root
}
...
}
//
While reading sources of other engines I found that 2nd variant is more common
(enable extensions at nodes not very deep). But my engine seems to perform
better with the first one! (faster solving tactical problems and analyzing). As
to strength, I did not found significant difference in these two versions
matches.
Dear GURUs, what can you advice? What is the more suitable place in the tree to
extend - near root or near leaves?
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