When a child has been sampled often through some other path a naive implementation may initially explore other less frequently visited children first. The new path leading to the transposition may therefore suffer from some initial bias. Using state-action values appears to solve the problem.
Erik On Mon, Oct 27, 2008 at 2:21 PM, Mark Boon <[EMAIL PROTECTED]> wrote: > A while ago I implemented what I thought was a fairly straightforward way to > deal with transpositions. But to my surprise it made the program weaker > instead of stronger. Since I couldn't figure out immediately what was wrong > with it, I decided to leave it alone for the time being. > > Just now I decided to do a search on transpostions and UCT in this mailing > list and it seems to have been discussed several times in the past. But from > what I found it's not entirely clear to me what was the conclusion of those > discussions. > > Let me first describe what I did (ar attempted to do): all nodes are stored > in a hash-table using a checksum. Whenever I create a new node in the tree I > add it in the hash-table as well. If two nodes have the same checksum, they > are stored at the same slot in the hashtable in a small list. > > When I add a node to a slot that already contains something, then I use the > playout statistics of the node(s) already there and propagate that up the > tree. When I have done a playout I propagate the result of the single > playout up the tree, but at each step I check in the hashtable to see if > there are multiple paths to update. > > I've seen some posts that expressed concerns about using the existing > statistics of another path. This may be the reason I'm not seeing any > improvement. So I was wondering if there's any consensus about how to deal > with transpositions in a UCT tree. Or if someone could point me to other > sources of information on the subject. > > Mark > > _______________________________________________ > 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/
