Author: José Carlos
Date: 08:47:35 09/11/04
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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? I guess you read it in Ed's programming page about Rebel. He does that in qsearch, and regarding checking moves generation. I tried his idea in my private program and it didn't work for me. It generated too many nodes, but I probably did something wrong. >How do people get around the cost >of determining that there is only >1 legal move? If you're in check (you know it before generating moves) you can use a special move generator that generates only escapes from check (capturing checking piece, moving the king, putting a piece in between...). In that case, you know in advance the number of legal moves. José C. >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
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