Author: John Coffey
Date: 13:48:57 09/28/98
Go up one level in this thread
On September 28, 1998 at 15:05:52, Chris Carson wrote:
>Take a look at the following links:
>
>http://www.xs4all.nl/~verhelst/chess/ - click on "Chess Tree Search"
>
>http://www.npac.syr.edu/copywrite/pcw/node341.html
> - click on "Sequential Computer Chess"
>
>http://www.maths.nott.ac.uk/personal/anw/G13GT1/compch.html
>
>Best Regards,
>Chris Carson
Thanks these are helpful. The first one contains the pseudo-code
that I had already seen. Wihtout fully understanding how
it works, I can use it as a starting point. Some questions ...
int AlphaBeta (pos, depth, alpha, beta)
{
if (depth == 0)
return Evaluate(pos);
best = -INFINITY;
succ = Successors(pos);
while (not Empty(succ) && best < beta)
{
pos = RemoveOne(succ);
if (best > alpha) alpha = best;
value = -AlphaBeta(pos, depth-1, -beta, -alpha);
if (value > best) best = value;
}
return best;
}
This code I understand, but .....
my question is about the following ....
"A fail low is when you search a position and return a score <= alpha. A fail
high is when you return a score that is >= beta."
What are the significance of "fail low" and "fail high" and how do they
affect the search?
John Coffey
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