Re: [computer-go] UCT tree pruning

Michael Williams Tue, 02 Jun 2009 12:17:16 -0700

Update:  After concentrating on tightening the UCT loop, I've optimized myself 
back into needing the SDD  :/


But now I should be able to get to 20B nodes in just one day.

(still only doing 7x7 Go)


Michael Williams wrote:

Yes, when memory is full, I save and free all leaf nodes (which is thevast majority). Nodes are loaded as needed.


Don Dailey wrote:

On Mon, Jun 1, 2009 at 4:57 PM, Michael Williams<michaelwilliam...@gmail.com <mailto:michaelwilliam...@gmail.com>> wrote:


    I've optimized my disk access to the point where I'm mostly CPU
    limited now, even when using a standard hard disk instead of an SSD.
     I can now create trees of up to about 30 billion nodes, which would
    take about a week.  The simulation rate is continuously going down
    because so much time is spent in UCT loops in the huge tree.

That's impressive. Are you doing things which move parts of the treeonto the disk and back when needed? I'm curious about the details!


- Don




    Don Dailey wrote:



        On Mon, Jun 1, 2009 at 11:22 AM, Isaac Deutsch <i...@gmx.ch

<mailto:i...@gmx.ch> <mailto:i...@gmx.ch <mailto:i...@gmx.ch>>>wrote:



            > Well, I'll take that over crashing with an out-of-memory
        error. :)

           Still, pruning seems better to me and has the same effect. ;p


        But is it better?   I think it's not so obvious without thorough
        testing.

        Pruning throw away information that is lost forever and may need
        to be recalculated.   Requiring more simulations does not throw
        out results, but results in some inefficiencies.   So it's not
        clear to me which is better - it may even be that it depends on
        how much you push it.   I am just guessing but I would guess
        that pruning is better in the short term, worse in the longer
        term.   Imagine a search at a corespondence level, where the

computer thinks for 24 hours. Which method is best there?Could you use hard disk or SSD? Using some kind of caching

        system,  where you relegate the oldest unvisited nodes to the
        hard dirve.   It may be that nodes you might normally prune are
        unlikely to get used again but if they do you still have the
        data.    This is no good unless you can guarantee that the disk

is used very infrequently - but with SSD it may be morepractical.



        - Don

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Re: [computer-go] UCT tree pruning

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