Author: blass uri
Date: 06:39:11 07/30/99
Go up one level in this thread
On July 30, 1999 at 08:52:04, Robert Hyatt wrote: >On July 30, 1999 at 00:28:06, Ed Schröder wrote: > >>On July 29, 1999 at 23:07:51, Robert Hyatt wrote: >> >>>On July 29, 1999 at 21:47:26, Peter McKenzie wrote: >>> >>>>On July 29, 1999 at 20:54:08, Bruce Moreland wrote: >>>> >>>>> >>>>>On July 29, 1999 at 18:58:12, Ian Osgood wrote: >>>>> >>>>>>Do other program authors curtail the search when there is a forced move at the >>>>>>root? >>>>>> >>>>>>How do you detect that a root move may be forced? >>>>>> >>>>>>Could you compare the values of the best and second-best root moves after a >>>>>>search iteration to detect a forced root move? (Granted, the second-best score >>>>>>won't be accurate due to alpha-beta, but I figure that if the difference was >>>>>>greater than a queen's value, you could still conclude that the best move was >>>>>>forced.) >>>>> >>>>>The only sure way to do this is if there is only one legal move. >>>> >>>>Another safe one is if you figure out that all other moves get mated instantly. >>>>I don't do that yet in LambChop, but it doesn't sound too hard. >>> >>> >>>How would you discover this? You get a score for the first move (the one you >>>think is obvious) and all the rest fail low and return alpha. >> >>Search the first iteration without alpha/beta. >> >>Ed Schroder >> > >How does that help? Peter said a move is forced if all other moves lead >to mate. Note to mate-in-one, but to mate-in-any. 1 ply search won't find >this. 1 ply search will find part of the forced moves and it is better than nothing. You cannot find all the forced moves because always there are cases when the mate is too deep for your ptogram. Uri
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