Sunday, April 26, 2009

Horizon effect

Early attempts at computer chess programs encountered a problem that became known as the horizon effect . The problem was because the programs were only looking a fixed distance (moves) into the future the programs would sometimes think they were avoiding a bad event when instead they were just delaying it. This would cause them to make mistakes. For example they might sacrifice a bishop thinking they were avoiding the loss of a queen when in fact the loss of the queen was just delayed by the opponent first having to take the bishop. This would increase the ultimate loss from a queen to a queen and a bishop.

Something like this effect appears to occur more generally. For example when Bush gave GM and Chrysler enough money to kept them alive until his term was over. Of course it is sometimes sensible to buy time but often it just increases the ultimate losses.

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