Black on roll. Does he have a double? Can white take if black doubles? Your opinion about both players' decisions?
Please DON'T post any bot info!! I will post rollout results after couple of days.



How do you analyze positions like this one?

I've made wrong decision as one of the players. I played the position about 20 times and I still don't understand it.

Would double as black. Race lead, semi-decent structure to start closing the board out, man in the air. Get gammons activated and push the advantage.

Pretty simple take for white imo. Black's structure is far from infallible, and White has solid game equity left with threats in the outfield and the four prime.

Double/take

This seems right on to me. good double, but easy take for white with a fair winning percentage, good structure on the other side of the board and low gammon threats.

Since white has an anchor, it's more a positional double than a blitz-double.

The Sylvester rule (PRAT rule) gives us 2 out of three, position and race are better, so it's a double.

For the Take/Pass decision I use the Robertie rule as a reference:

white has an anchor: yes
There is contact: yes
Is it a 5-prime: No

So this should be a Take (a 5-prime would be a pass).

But: In the Robertie rule we don't have an extra man back (as white has here). +1 towards pass
And the extra checker is on the bar. +2 towards pass.
But the contact on the other side is extra tough. +1 towards pass.

So I would say Double/Pass

This looks like no double/take to me. Black has two stripped outfield points and his spares to build with in the home board, he can use the outfield points to grab his 4 pt but will probably have to break his 8 pt to do it unless he rolls well. Add to this his two trapped guys behind whites 4 prime with lots of spares to attack/build with....and in case he does jump with a 6 whites got an sentry in the outfield.

No double/take

I read the other posts and I have been looking closer.

Does black have a lot of awkward moves:

D5,54,52, maybe 32 are not constructive but not blotting either.
Chances are only about 4% (7/36^2) that these moves occur twice.

The rest of the 5's play good, as do all 6'es.
The 4's make an extra point, also D3, D2, 21, and 31 anchors,

So apart from the static analysis, the dynamics supports a double/pass

OTB I was sure this is a double, probably costing 0.050 - 0.100 if I don't double now.
What really shocked me is that I was about 0.150 off in my estimations.

As I already said - I played out the position, but even still, I wasn't convinced, so I decided to post this on three forums (DailyGammon, BgOnline, TwoPlusTwo) to see two things:
1. How other players feel about doubling this
2. Will I get some passes to make doubling practically correct

Here are combined results:
ND/T 6 votes
D/T 13 votes
D/P 1 vote

1. Most players doubled this. And I can't blame them/us. It still looks like a double to me.
2. Not enough passes to make doubling practically correct.

Hi,

oops i was pretty wrong here (even wronger (is this a word?) than you miran).

I guess i underestimated the dynamics on the white side.

For example this sequence:
black stays vulnerable after his move
White enters
black stays vulnerable
white makes a 5-prime or white gets more outfield control

Thanks for posting, it was very instructive

i just put the position in extreme gammon with the result, double drop

then i saw that the bearoff is on the right!!!!

and when i saw the position now right, why would you even consider doubling??

you are stuck with two checkers, behind a four prime with several builders on it

and you will never blitz out white

Ahead in race, bigger board, opponent on the bar, less men back, etc.