Author: John Coffey
Date: 13:48:57 09/28/98
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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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