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Subject: Re: Threat extensions

Author: Stuart Cracraft

Date: 07:15:32 09/27/04

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On September 27, 2004 at 02:15:42, Daniel Shawul wrote:

>On September 27, 2004 at 01:03:39, Sergei S. Markoff wrote:
>
>>>Sergei -- when you refer to the leaf and pre-leaf we assume you
>>>mean depth == 0 and depth == 1 respectively. Please correct this
>>>if we are wrong.
>>
>>You're right. The main idea is to decrease rate of cases in which after threat
>>we're going into quiescence with it's null move. Pre-leaf (depth==1) nodes are
>>important because it's preferable to detect threat chains.
>
>after reading what you and tord wrote some time ago on this extesnion,
>i tried it. First time i did for the whole big depths and it slowed down
>my search considerably. then i restrained it to depth < 2*UNITDEPTH
>and it is working fine now.
>
>Another thing i tried is , i search the "mate threat move" and the other
>"threat move" next to hashtable move. This also improved my move ordering.
>
>thanks for sharing your ideas!
>
>daniel

Then I have a question for you.

Here is your null search and mate threat

null move
if (okaytodonull) {
  makenull
  value = -search(depth-R-1,-beta,-beta+1)
  unmakenull
}
// mate threat
if (!extended && value == -MATE+ply+2) {
  extended = 1;
  extend+=1.00;
}
:
:
if (extend>=1) depth++;
:
:
rest of search

Did I get it wrong? How do you implement mate threat? Especially obtaining
any threat move that counters the null move.

Stuart



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