Author: Michael Henderson
Date: 20:34:15 09/10/04
Go up one level in this thread
On September 10, 2004 at 21:35:58, Stuart Cracraft wrote: >I read, somewhere, and I forget who, about >if 1 legal move, extend 2 ply, >2 or more legal moves, then 1 ply. >Anyone have any stats on the effects >on play of the above instead of >always extend 1 legal move. Does it >blow up? > >How do people get around the cost >of determining that there is only >1 legal move? > >For me, that's an expensive operation >involving usually dozens of makemove/unmakemove's >with a test to see if the king is attacked, >at every single node, before doing the search >of the 1 move with the increased depth. > >Only rarely is it just 1 legal move to get >out of check. But the determination of that >is not rare. It has to be done for every >sweep of the moves at each node. > >Thanks, > >Stuart I extend 1.75 plies for incheck (2 plies crashed the program). 1 legal move extensions are usually rare so i don't worry about blowups. If you use bitboards the check stuff is a snap...but with other board representations it's not so fast. If you are in check you might just generate check evasions (if it's better) to save time.
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