On Tue, May 12, 2009 at 8:17 PM, Dave Dyer <[email protected]> wrote:
> > > > >If I use persistent storage and do that search again in another game, I > can start exactly where I left off and generate 50,000 more nodes. It will > be the same as if I did 100,000 nodes instead of 50,000 nodes. Or put > another way, it will be the same as if I spent 20 seconds on this move > instead of 10 seconds. > > Sure, but except for openings you'll never reach the same > position position in another game unless the players are > deliberately copying their play. I think you still miss the point. I don't expect this to help on move 20, only for the early positions you have seen before. When I play chess, I play the first few moves almost instantly, without making a blunder. I can do this because I have studied those positions and know them thoroughly. It's not because I memorized them, even though I have. As soon as I get to positions I am less familiar with, I slow down to a crawl, because now I have to try to figure them out over the board. Of course my knowledge of the opening helps some, even when I'm out of the book I have a good sense of how to proceed. With GO, a computer can do the same. It's almost ridiculous to search the opening position from scratch, as it we are a totally moron and have never see that position before. There is no reason not to study it and remember what we learned about it. There is no reason not to apply this to as many moves as possible in the opening, even if it's only a very few. I don't understand why this is not immediately obvious to you. What I suggest is superior to just memorizing what moves to play, you can actually save the tree and in a sense it's like a program actually understands the position, not just play by rote. If it's a position you already searched, you will have at least a little head start no matter what the opponent plays. Even if the opponent surprises you, you will have a piece of the tree intact and the next time this same situation happens, you will now have some serious analysis already pre-computed. With 19x19 this is probably not a huge ELO booster, but there is certainly nothing unsound about it either. And it may not be as bad as you think because the computer will tend to be deterministic about which moves it plays which by itself drastically lowers the branching factor. If it fails to play the same in a position it has already seen, that is not a bad thing either, it indicates that it found a move it likes better, perhaps discovering that something was wrong with the previous choice. That's exactly what you hope it does. > > Consider move 20 (for example). If you saved every "move 20" node you > ever encountered, how often do you think you'd encounter a duplicate > from a different game, such that you can either avoid an evaluation, > or improve your knowledge of that position by studying it > a bit more. I contend it is a vanishingly small percentage. I don't believe you want to save the tree beyond the point where you are in a position you have never seen for the very reason you state. It's very unlikely that you will still be a part of the tree you have visited before. I thought I already conceded that point? Didn't I already say that this is an idea for the first few moves? But this idea will save you time that can be spend in later moves, so it can actaully benefit the moves you make later in the game. But more importantly it can prevent you from being in a losing position by move 20 from a bad move choice on move 5. - Don > > > -- > > _______________________________________________ > computer-go mailing list > [email protected] > http://www.computer-go.org/mailman/listinfo/computer-go/ >
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