I'm curious about a couple of things in particular. Is this a bug and how much time would be required for Mogo to have played the correct move if it wasn't.
Of course I'm also interested in ways to solve this with less deep searches or better play-outs. - Don On Mon, 2008-09-22 at 13:59 +0200, Magnus Persson wrote: > Quoting Mark Boon <[EMAIL PROTECTED]>: > > > Playing out that fake ladder in the first game meant an instant loss. > > Surprising. And embarassing. Any information on the number of > > processors used? > > > The interesting question is if there is a silly bug or something more > sophisticated. > > I have struggled with ladders in Valkyria and it is often really hard > to tell what causes these problems. In Leksand most games on 19x19 > where lost in a ways similar to the recent mogo game. I could not find > an obvious problem with the playouts at least not in terms of an > easily fixable bug. Note that Valkyria reads out 99% of all ladders > correctly both in the tree and in the playouts. > > What I realized was that AMAF in combination with heavy playouts > causes some serious biases, for some kinds of very bad moves such that > AMAF completely misevaluate them. > > In the case of the ladders the heavy playouts of Valkyria correctly > prunes playing out ladders for the loser. But sometimes in the > playouts the ladder is broken and after that there is a chance that > the stones escape anyway. This means that almost always when the > escaping move is played it is a good move! Thus AMAF will assign a > very good score to this move.... > > My solutions to this was simply to turn off AMAF-eval for all shapes > commonly misevaluated for ladders. But I think this problem is true > for many shapes > in general. What makes ladders special is that the problem repeats it > self and the effect get stronger and thus even more likely the larger > the ladder gets. > > I think a better solution would be to modify AMAF in some way to avoid > these problems, or perhaps change the playouts in a way to balance the > problem. Does anyone know something to do about it or have any ideas? > > -Magnus > > > _______________________________________________ > computer-go mailing list > computer-go@computer-go.org > http://www.computer-go.org/mailman/listinfo/computer-go/
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