Author: Don Dailey
Date: 12:16:51 12/07/97
Go up one level in this thread
On December 07, 1997 at 14:12:30, Enrique Irazoqui wrote: >On December 07, 1997 at 14:01:13, Don Dailey wrote: > >>On December 07, 1997 at 13:41:03, Jari Huikari wrote: >> >>>On December 07, 1997 at 13:14:54, Don Dailey wrote: >>> >>>>>Could you tell me what is the maximum number of legal moves in a >>>>>chess game position? >>>>>A) In theory? >>>>>B) In practice? >>> >>> >>>>I don't believe this is known. It might be fun to make a contest >>>>out of this though. Can somone post a position with a high number >>>>of legal moves? And the rest of us will try to better this? >>> >>>>The rules are: >>> >>>>1) Must be a fully legal position, (no more than 9 queens for >>>>instance.) >>>>2) Post in FEN. >>> >>>I think that some chess programmers must have thought this question some >>>time. >>> >>>I remember a 'mate in one'-position having 175 or so legal moves. Over >>>100 >>>of them were mates. >>> >>>Perhaps someone has statistics from 'real' games. BTW: What's the >>>average >>>number of moves precisely? I know it's about 30, maybe a little more. >>>(In >>>middlegame anyhow.) >>>I already know, that minimum is zero (in mate or stalemate. :-) >>> >>>(I _may_ have some use for these information in my new program.) >>> >>> Jari >> >>I'm using my program to search for NORMAL positions with lots of legal >>moves. >> >>I'm sure I can do much better but to kick this off, can someone beat >>65? I know it's possible to find positions with over 100. >> >>Pehaps some modification of the 8 queens solution will give us a >>nice lower bound on the most "complicated" position. >> >>Don >> >> >>3r2k1/1p3ppp/p4P2/P3r3/1P3nPP/5RQ1/2q5/R6K b - - ; 65 legal moves. >> >>P.S. I haven't checked this for accuracy yet. > >Q6Q/4Q3/1Q6/5Q2/2Q5/R5Q1/3Q2NN/1R3KBk w - - ; 195 moves. > >I'm sure is improvable. > >Enrique > >>Don Is this the 8 queens idea with some mods to make it legal? Nicely done! Can we get past 200? How did you count them? I'll post the best position my program comes up with by searching from normal positions. Since my last post it has found a 68 legal move position, but I think it will do better. Pehaps another useful thing would be to consider only positions that are a subset of the opening position. In other words, only 1 queen allowed, 2 rooks etc. We could define these as "normal" positions and constructions like yours as "constructed" positions. It will be interesting to see if we can get past 200 with constucted positions (I believe we can) and past 100 with normal positions (probably can too.) Don
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