Author: Dave Gomboc
Date: 00:34:17 09/11/99
Go up one level in this thread
On September 11, 1999 at 02:28:00, Ed Schröder wrote: >>There are only three choices here. >> >>(1) best <= alpha. We don't know anything about any of the moves. Yet I >>believe Ed (and I thought you as well) said that if you take this 'best' >>move and store it in the hash, it works well. In my test, it didn't. >> >>(2) alpha < best < beta. This is a move with an _exact_ score that is >>correct. Also known as a PV-candidate move normally. >> >>(3) alpha < beta < best. This is a fail high move. It is better than the >>best that is allowable. It is _not_ the best move at this level however, >>it is just good enough to produce a score >= beta and terminate the search early. >>This is the case that feeds (1) above at the previous ply. If we try >>_another_move here we might get an even _bigger_ score here, and back up an even worse >>score to the previous ply. But alpha/beta makes us stop _now_. > >I like to try this. One question: what is "best"? > >the score of the node? > >the best score sofar on this ply? "best" is initialized to -oo before the subtrees are searched. At any given time, "best" is the best backed-up score or bound from the subtrees that have been searched. >Ed P.S. Why do I always see INF or INFINITY in people's code? I always use "oo". :-) Dave
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