On Jan 18, 2009, at 5:38 PM, Magnus Persson wrote:
In Valkyria I solved this by playing out the ladder on the playout
board, and store all changes on a stack. When the ladder undos moves
it just pop changes from the stack. In this way I can also use the
rich board representation of Valkyria to setup the ladder fast. The
drawback is that the code is ugly and slightly buggy when stones are
sacrificed during the search.
A todo thing is to write a more correct ladder reader that still
uses the idea of sharing the array with board with the playout, so
that no copying has to be done.
My ladder code re-uses the board array of the playout module. But
copying this array before reading a ladder doesn't slow things down
all that much. As has been discussed on this list elsewhere, copying
an array is fast nowadays. Re-using the array is actually a way to
make sure your ladder-reading is without bugs when doing undo. If
something goes wrong you notice immediately...
Maybe what David alluded to is that the playout has no undo so he
can't use it to play and undo moves during ladder search. In my case
the ladder reader only needs an array with the position. For the rest
it's completely self-contained. That adds maybe a little bit when
setting up the ladder reading, but it's still fast.
Mark
-Magnus
Quoting David Fotland <fotl...@smart-games.com>:
I think it is too expensive to read ladders during playouts. I
remember
that you have faster ladders search code so it might not cost you
as much.
My playout code has no ability to undo a move or do any kind of
lookahead.
David
--
Magnus Persson
Berlin, Germany
_______________________________________________
computer-go mailing list
computer-go@computer-go.org
http://www.computer-go.org/mailman/listinfo/computer-go/
_______________________________________________
computer-go mailing list
computer-go@computer-go.org
http://www.computer-go.org/mailman/listinfo/computer-go/
