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this should be easy.. - ROLLOUT

Posted By: Timothy Chow
Date: Saturday, 28 June 2014, at 2:07 a.m.

In Response To: this should be easy.. - ROLLOUT (Bob Koca)

Bob Koca wrote:

Considering how language works why in your definition 1 why should the less connected to cube suddenly mean more than just no cube but also no match?

I just explained this in excruciating detail. Let me try again.

Definition 2 looks simpler and more intuitive at first, but it's ambiguous. At a score when the cube is live, what does it mean to assess the probability of winning "with no cube"? You can't just remove the cube; you have to define how subsequent play is to proceed. Are the players supposed to play out the rest of the match without a cube, using a cubeless MET? Or do they just play out the rest of the game without a cube, understanding that the cube will be reinstated after the game is over? Or by "with no cube" do you mean "cubeless" in the sense of Definition 1? Given this ambiguity, I think that it's ambiguous what "cubeless" means even at n-away Crawford when n ≥ 3. Does the cube get reinstated after the conclusion of the current game? Even at GS/GG/DMP, Definition 2 strikes me as ambiguous because it could refer to Definition 1. This is especially true if we agree to use Definition 1 except at GS/GG/DMP; it seems pretty confusing to me to use Definition 1 at all scores except GS/GG/DMP and then switch to some other definition of "cubeless" just for those three scores.

The other argument for using Definition 1 is that this is what the bot writers have in mind. When Snowie reported cubeless numbers, it meant Definition 1. In particular, when Snowie reported cubeless numbers at (say) gammon save, it did not mean ATS numbers. Even for modern bots, during a rollout, if there is a D/P that forces the bot to generate an estimated "cubeless" equity, they try their best to come up with an estimate in the sense of Definition 1. Now, it's true that at gammon save (for example), the "cubeless" probability of winning that it ends up computing happens to be the ATS probability of winning, but to me, this is an artifact of the algorithm. The algorithm, in general, isn't trying to compute the ATS probability of winning. It's trying to compute the cubeless probability of winning in the sense of Definition 1, and the fact that at some scores it winds up computing the ATS probability of winning instead is, in my mind, an "accident" of sorts.

The "cubeless probability of winning" being different from the "probability of winning" when the cube can no longer be used in a match such as at GS, GG, DMP is strange to me. What is the need to even mention cubeless, pseudocubeless, or whatever cubeless at all at those scores?

Frankly, I agree with you. I prefer to see actual statistics rather than cubeless statistics, and have argued this for years. But the BG community appears to demand to see cubeless numbers, or something like them, at all scores. Given that the numbers are there on the screen, if I want to refer to them, I have to use some term. If I leave out the word "(pseudo)cubeless," I feel that I do the BG community a disservice, because most people aren't aware that those numbers are ATS figures at some scores but not others. By using the word "pseudocubeless" I remind people that those numbers need to be interpreted with caution.

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