Minimum depth for null move

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Minimum depth for null move

Postby pkumar » Sun Feb 01, 2015 5:06 pm

As in many other programs, minimum depth for null move is 2 for crafty 24.1.
Code: Select all
    if (do_null && !pv_node && depth > 1 && !in_check &&
        TotalPieces(wtm, occupied)){
............code.....
      if (depth - tdepth - 1 > 0)
        value =
            -Search(tree, -beta, -beta + 1, Flip(wtm), depth - tdepth - 1,
            ply + 1, 0, NO_NULL);
      else
        value = -Quiesce(tree, -beta, -beta + 1, Flip(wtm), ply + 1, 1);
............more code.............
    }

What is wrong with minimum depth of 1? Apparently some nodes would be saved by dropping straight into Quiesce.
pkumar
 
Posts: 2
Joined: Thu Jul 31, 2014 6:09 pm

Re: Minimum depth for null move

Postby hyatt » Sun Feb 01, 2015 7:23 pm

if you use "1", how can you save anything? A normal search will drop directly into q-search. If you reduce the depth you STILL drop directly into the q-search. Nothing saved. Thats why I have the restriction...
hyatt
 
Posts: 1242
Joined: Thu Jun 10, 2010 2:13 am
Location: University of Alabama at Birmingham


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