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[Bug-gnubg] Current categorization of doubling mistakes (new thread)

From: olivier croisille
Subject: [Bug-gnubg] Current categorization of doubling mistakes (new thread)
Date: Tue, 07 Oct 2003 04:17:01 +0200

I still strongly disagree with the new categorization of doubling mistakes.

Here's a doubling decision I had tonight on GG against Martin Krainer in a 7 pointer:
Position ID : m2zgAUTLNiAWAw

Cube analysis
2-ply cubeless equity  +0,566 (Money:  +0,538)
  64,3%  34,9%   1,1% -  35,7%  10,7%   0,2%
Cubeful equities:
1. Double, take         +0,831
2. Double, pass         +1,000  ( +0,169)
3. No double            +0,743  ( -0,088)
Proper cube action: Redouble, take

I failed to redouble here, underestimating my gammon wins. Incidentally, with Position ID, you will realize TG is not even an issue to consider. But Gnubg classified this mistake as 'Missed double around CP' : I'm sorry I have to say this doesn't make sense *at all* to me. *No way* this position can be TG, still that is what the wording implies, as Gnubg basically tells me I forgot to cash, eventhough it's a huge take (I *do* know it doesn't tell me that, but it sure sounds like it, the use of the words Cash Point is totally counter-intuitive).

Now I realized where the pb comes from and why Gnubg now classifies a vast majority of missed doubles as 'Missed double around CP' : you can sum it up in just one word, and that is EFFICIENCY. In BG, you want to send over cubes as *efficient* as possible, in other words, as close to your CP as possible.

The above-posted doubling categorization therefore illustrates the following problem : a majority of cubes will be sent with some degree of efficiency (varying with the level of players), which very often translates in maths terms into a double that is closer to CP than DP. Only exceptions occurr when volatility is *very* high on the next roll/next exchange, or in a last roll position (this is actually a very specific sub-case of the first case) or in long matches when you have a huge lead and your market window is very tiny.

In the position referred to, my Doubling Point was 46.3% and my CP 68.4% : have a guess, in 90% of cases, which one I will be closer to when I redouble...?

Therefore, eventhough there is a *majority* of Missed double/take mistakes made in actual play, I would bet 'Missed double around DP' will from now on be a tiny minority of doubling mistakes, as reported by Gnubg : because the mathematical DP is extremely rarely used in practice for doubling decisions. (Pararrel question : so, if this theoretical DP is almost useless for making/classifying doubling decisions, any chance we can 'build' an empirical DP taking into account cube efficiency?)

So, because of efficient doubles, we end up with a predominant 'Missed double around CP' category ; this introduces confusion because it now intuitively sounds as you missed a double/pass (because of the words Cash Point) eventhough this category still refers to a majority of Missed double/take!!

Why on earth did we change categories in the first place anyway? I do favor change, and obviously improvements take time to implement, but here I cannot see *any* value-added over the former categories that were working sooooo fiiiiiiiine, without any mistake in 2 years+ in categorizing doubling mistakes. In the contrary, I just can see confusion for beginners/intermediate players.

Incidentally, Gnubg also went wrong a couple of rolls later in that very same game, when I decided to redouble :

Position ID : 29qAAQybbQwZAA

Cube analysis
2-ply cubeless equity  +0,447 (Money:  +0,441)
  69,6%   9,2%   0,1% -  30,4%   4,4%   0,0%
Cubeful equities:
1. No double            +0,752
2. Double, pass         +1,000  ( +0,248)
3. Double, take         +0,681  ( -0,071)
Proper cube action: No redouble, take (22,4%)

Gnubg classified this as 'Wrong double around CP' eventhough as you can see, it's a huge take, so cashing is not even an issue unless the opponent makes a triple whopper (a 0.319 blunder). Then again, the use of the words Cash Point is confusing. I would rename this as something like 'Missed double around practical DP' (if we can figure out any such concept, taking into account cube efficiency as I suggested above)

I think it should be clear by now that there is no additional information provided. Instead, categories were just switched, and with very few exceptions, you will just see two blank lines in front of 'Missed double around DP' and 'Wrong double around DP' categories.

French Kiss on GG

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