Cube 118 - 2-away and 3-away

[sixty_something]

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GNUbg says the correct actions are

Spoiler

This has been one of my most common mistakes lately, a too agressive cube when 2-away and a recube by my oppenent will make it a DMP or put me into a Crawford game situation should i lose the game .. i understand the math behind why this is a doubtful cube, but still i fall into the trap of cubing .. i'm looking for a good rule of thumb how to correctly evaluate these situations .. anyone have a suggestion?

meanwhile, the math is fairly simple .. according to the cube analysis below, i have a 22% chance of a gammon or backgammon for the win with a 33% chance of a win forcing the Crawford game at 4-2, very strong match winning chances .. however, with the cube and almost automatic take and redouble opportunity, i am giving my opponent a nearly 35% chance of winning the match in this one game and the match - a far better chance than he would have otherwise regardless of our relative strength

in this match, the finals in adz's "cheap and nastyl" - 3/5 tourney, i got lucky and closed out johwayne who missed a shot forced by a 64 roll as i was coming in and facing a nearly closed board had i been hit .. but more often than not lately, i have wound up regretting a cube like this one

Cube analysis
4-ply cubeless equity  +0.589 (Money:  +0.452)
  0.655 0.205 0.013 - 0.345 0.074 0.002

Cubeful equities:
1. No double            +0.547
2. Double, pass         +1.000  ( +0.453)
3. Double, take         +0.211  ( -0.336)
Proper cube action: No double, take (42.6%)

even after a hit, RED's response is almost a given recube


Cube analysis
0-ply cubeless equity  -0.278 (Money:  -0.513)
  0.326 0.077 0.002 - 0.674 0.226 0.017

Cubeful equities:
1. Double, take         -0.051
2. Double, pass         +1.000  ( +1.051)
3. No double            -0.124  ( -0.073)
Proper cube action: Redouble, take

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Position ID: 4PXgATCwW/ABEQ Match ID: cAmgACAAGAAA
               
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[PersianLord]

Spoiler

Well, I voted D/P because I mistakenly thought that white is trailing 3-2. 

i'm looking for a good rule of thumb how to correctly evaluate these situations .. anyone have a suggestion?

Well, you know I'm just an intermediate, but my 2 cents is to not double in these situations until it's a plain race/non-contact game with a reasonable lead. In these volatile positions where there's still lots of contact, doubling is a blunder always, I think.

according to the cube analysis below, i have a 22% chance of a gammon or backgammon for the win with a 33% chance of a win forcing the Crawford game at 4-2, very strong match winning chances .. however, with the cube and almost automatic take and redouble opportunity, i am giving my opponent a nearly 35% chance of winning the match in this one game and the match - a far better chance than he would have otherwise regardless of our relative strength

Also note that your 20% chances of gammoning him will render useless if the cube/recube scenario happens. That reasoable gammon probability is an invaluable asset which should be cared of.

regards

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[dorbel]

I suspect everybody else knows how to do this, but how do you activate the spoiler thingy when posting?

[socksey]

It's the yellow and black circle with triangles in it next to the last choice of selections when you post.     When you place your curser over the choices, they tell you what they are.

socksey




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[dorbel]

Spoiler

You don't need any very sophisticated calculations to handle these. While you have an enhanced gammon chance, i.e. more than you started with, you keep playing for a gammon. A double becomes correct when you feel that you are near to winning three games out of four, but your gammon chances have faded. Here about 20% of the games end in a gammon for White, more than the 12-13% that he started with, so a double would be quite wrong. Note that White's hitting threat isn't very great. As he is trying to win without doubling for the moment, hitting numbers like 5-3, 4-2 and 3-2 shouldn't be used for hitting and 4-1 is doubtful.
If you are a weak player playing a very strong one, doubling now becomes much more attractive. He'll take and redouble for sure, but he won't like it much. He can't use any cube skill and his opportunities to outplay you with the checkers will be limited. Double, don't hit with the above numbers and you may well get lucky!

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[spielberg]

Spoiler

Hooray for an easy one! It can't be double/take given the match score and even a poor player willl recube (I'd hope). It's obviously not a drop either. Given the gammon value white loses next to nothing by playing on. (black's future decisions on cubing will also become considerably more difficult as the chance of them losing the match with an uncubed gammon increase). So white's too good to cube I reckon.
PS could we have that as an option in future polls? (I know it's obviously included in the "no double" it's just the reason it's not a double is key)

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[dorbel]

A terminological error Spiel. Although White should play on for the gammon for the moment, he isn't too good. A player is said to be "Too good to double" when his opponent should pass if doubled and the player's equity is greater than 1 if he refrains from cubing. That isn't the case here.