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DQ: Consider the bar point? *** Rollout ***

Posted By: Timothy Chow
Date: Friday, 18 July 2014, at 10:14 p.m.

In Response To: DQ: Consider the bar point? *** Rollout *** (leobueno)

So, if XG says after n games rolled out that the probability of a move being right is 100% and the other evaluated moves' probability of being right is 0%, what is gained by rolling the position further (increasing n)?

In a separate post, you asked about error/blunder thresholds. To me, that indicates that you care not only about which play is best, but by how much the best play is better than your erroneous play. Right?

Imagine the following scenario, Scenario A. You make a play and the computer says, "I'm 99.9% sure that your play is wrong. It might be wrong by 0.001 or it might be wrong by 0.500; I have no idea. But I'm very sure that it is wrong."

Now imagine the following scenario, Scenario B. You make a play and the computer says, "I'm unsure about your play. I'm 99.9% sure that if it's wrong, then it's not wrong by more than 0.002, and if it's right, then it's right by no more than 0.001, but I'm only 53% sure that it's wrong."

In which scenario would you wish that you had more information? For me, it's Scenario A, hands down. I'd really like to know if my play was a quintuple whopper or if it was basically tied with the best play. Just knowing with 99.9% certainty that it's not the top play is nice, but I'd like to know more. But in Scenario B, I don't really care to know more information. If I'm 99.9% sure that my play is with 0.002 of the best play, I'm satisfied. I don't feel the need for the computer to keep churning away for hours until it tells me that it's 99.9% sure that my play is wrong.

I've exaggerated Scenario A slightly for effect, but the point is that percentages that you're focusing on are telling you just whether your play is wrong. In Scenario A, you would see the number 99.9%, and in Scenario B, you would see the number 53%. But it's Scenario A, in my opinion, where you want to roll the decision out longer, not Scenario B.

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