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Subject: Re: Limit extensions

Author: Anthony Cozzie

Date: 10:28:40 07/06/04

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On July 06, 2004 at 13:21:27, Dan Honeycutt wrote:

>On July 06, 2004 at 12:30:48, Jeff GAZET wrote:
>
>>Hi,
>>
>>i'm not sure about the way to limit extensions into the search tree.
>>I think some code will be easier to understand than my english. Example :
>>
>>search(int depth,int alpha,int beta...)
>>{
>>int base_extended=0, extended;
>>
>>if(InCheck(side)) {depth++; base_extended+=ONEPLY;}
>>
>>foreach(move)
>>   {
>>   extended=0;
>>
>>   if(is_pawnn_push_7(move)) {depth++; extended+=ONEPLY;}
>>   if(is_recapture(move)) {depth++; extended+=ONEPLY;}
>>
>>   if(extended>ONEPLY) {extended=ONEPLY;}
>>   if(base_extended+extended>TWOPLY) {extended=0;}
>>
>>   domove()
>>   score=-search(...);
>>   undomove()
>>
>>   if(extended) {depth-=extended;}
>>   }
>>}
>>
>>Is that right ?
>>
>>Regards.
>
>Why don't you extend the move rather than the position.  ie:
>
>foreach move
>  domove(move);
>  extended=0;
>  if(is_pawnn_push_7(move)) extended+=ONEPLY;
>  if(is_recapture(move)) extended+=ONEPLY;
>  if(is_check(move)) extended+=ONEPLY;
>  if (extended > LIMIT) extended = LIMIT;
>  score = -search(depth+extended, ...);
>  undomove(move);
>
>Dan H.

Some extensions (extend out of check, mate extension) apply to positions.
Others (recap, singular, extend in check, pawn push, etc) apply to moves.  Zappa
handles both, of course, although I only use check & mate extensions.

anthony



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