Computer Chess Club Archives




Subject: Re: The "same threat extension" as effective way to resolve horizon prob

Author: Sergei S. Markoff

Date: 07:02:25 10/01/03

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>I just posted a message almost identical to my current one on the Winboard
>forum, but I guess CCC is a better place to discuss this.  Is the pseudo-code
>below a correct implementation of your idea?

I have two corrections.
1. Uri is right. The same piece capture isn't always the capture to the same

>int search(int alpha, int beta, int depth) {
>  int value, null_value;
>  move_t *move;
>  if(depth <= 0) return qsearch(alpha, beta, depth);
>  make_null_move();
>  null_value = -search(-beta, -alpha, depth-R-1);
>  unmake_null_move();
>  if(null_value >= beta) return null_value;
>  else ThreatMove[Ply] = CurrentMove[Ply+1];

if(SameTarget(ThreatMove[Ply],ThreatMove[Ply-2])) extend_flag=true;

// Then you must use this flag to add about 1/2 plies to all moves
// in this node, but take care of extension limitation

Best wishes,

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