The number of legal 17x17 Go positions is ...

[tromp]

19079388919628199204605726181850465220151058338147922243967269231944059187214767997105992341735209230667288462179090073659712583262087437

making up about 2.47% of all (legal+illegal) 3^289 17x17 positions.

The computation took over 8000 CPU-hours and 3TB of disk space,
generously provided by the Opteron based Linux Cluster of the INS group
at
the Center for Mathematics and Computer Science (CWI) in Amsterdam.

Many thanks to my colleague Michal Koucký for helping develop the
software.

All known exact counts and accurate estimates are available at

http://www.cwi.nl/~tromp/go/legal.html

Also available now is the paper

"Combinatorics of Go"

by Gunnar Farnebäck and myself,
explaining in detail the algorithm for counting.

As usual, comments and suggestions are more than welcome.

regards,

%!PS % -John Tromp (http://www.cwi.nl/~tromp/)
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[abu...@ieee.org]

tromp wrote:
> regards,
>
> %!PS % -John Tromp (http://www.cwi.nl/~tromp/)
> 42 42 scale 7 9 translate .07 setlinewidth .5 setgray/c{arc clip fill
> setgray}def 1 0 0 42 1 0 c 0 1 1{0 3 3 90 270 arc 0 0 6 0 -3 3 90 270
> arcn 270 90 c -2 2 4{-6 moveto 0 12 rlineto}for -5 2 5{-3 exch moveto
> 9 0 rlineto}for stroke 0 0 3 1 1 0 c 180 rotate initclip}for showpage

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Adam