There is a book (2nd Book of Go, I think) that teaches how to count liberties in a semeai. Once O plays C9 it has far more than two liberties, since black has to play approach moves on either side to win the semeai. For example, black has to play 3 times to fill the liberty at D9, and black can never fill the liberty at A9. So O has at least 4 liberties after C9 is played.
If you count "semeai liberties" correctly, it's obvious that white C9 group has more liberties than the black group (after C9 is played). So Many Faces can see directly that O wins the semeai after C9 is played. So a one ply search finds that C9 is a good move. Many Faces' heuristics then encourage the UCT search to try this move first, and it holds up well in the playouts. David > -----Original Message----- > From: [email protected] [mailto:computer-go- > [email protected]] On Behalf Of Brian Sheppard > Sent: Monday, June 22, 2009 3:01 PM > To: [email protected] > Subject: [computer-go] Position Rich in Lessons > > > What rule proposes C9 in Many Faces or Valkyria? > > 1 2 3 4 5 6 7 8 9 > A - - - - - - - - - > B - O O O O X X X O > C - X X X O O X O - > D - O - X O X O O - > E O - O O X X O X X > F - O X X X X X O - > G - X X - - O X O - > H X O O O - - X X O > J - - - - - - - O - > > On the face of it, C9 doesn't put O ahead in any semeai. After C9, O is > behind X's B8 string by 3 liberties to 2, and O is behind X's E8 string > by 2 liberties to 2 with X to move. > _______________________________________________ computer-go mailing list [email protected] http://www.computer-go.org/mailman/listinfo/computer-go/
