5a 3a deuce point game recube to 4?

[Walt]

XGID=-ABCBCB------------ba-dBf-:1:1:1:00:0:2:0:5:10

X:You O:O
Score is X:0 O:2 5 pt.(s) match.
+13-14-15-16-17-18------19-20-21-22-23-24-+
| | | O O O X O |
| | | O O X O |
| | | O O |
| | | O O |
| | | 6 |
| |BAR| |
| | | |
| | | |
| | | X X | +---+
| | | X X X X X | | 2 |
| | | X X X X X X | +---+
+12-11-10--9--8--7-------6--5--4--3--2--1-+
Pip count X: 95 O: 35 X-O: 0-2/5
Cube: 2, X own cube
X on roll, cube action

[badgolferman]

Double/Pass
It seems obvious to me, maybe I'm missing something.

[Bradley K. Sherman]

Walt <walt_...@yahoo.com> wrote:
>Score is X:0 O:2 5 pt.(s) match.
> +13-14-15-16-17-18------19-20-21-22-23-24-+
> | | | O O O X O |
> | | | O O X O |
> | | | O O |
> | | | O O |
> | | | 6 |
> | |BAR| |
> | | | |
> | | | |
> | | | X X | +---+
> | | | X X X X X | | 2 |
> | | | X X X X X X | +---+
> +12-11-10--9--8--7-------6--5--4--3--2--1-+

> X: 95 O: 35, X on roll, cube action

Because of the match score and O's gammon chances
if we miss:
Redouble/Take

--bks

[Tim Chow]

On May 4, 9:48 am, "badgolferman" <REMOVETHISbadgolfer...@gmail.com>
wrote:

X hits with only 13/36 rolls, and if X misses, O is the favorite.
What looks obvious to me is the take, and I don't understand how you
can think that the pass is obvious. Maybe you thought O was on roll?

In general I find that if you're trailing at 4a3a or 5a3a then you
should recube to 4 when you get your last-ditch shot if you have a
killer board (as you do here). That could be too simplistic a rule of
thumb but it's what I'll go with here.

---
Tim Chow

[badgolferman]

Yes, I did miss something. For some reason I thought O was on the bar.

Double / Take.

[Freeven]

Can O take? His TP is about 33%. He looks like a clear favorite, so the
take should be easy.

X hits 13/36, or 36%, immediately. If he misses (64%), he usually gets a
second chance next turn on O's 65 64 63 62 54 53 52 51 33 = 47%, and
he'll hit about a third of those, for (.64 x .47)/3 = 10%. So over the
next two rolls, X hits about 36+10 = 46%. He doesn't always win when he
hits, but that's a lot of market losers, plus a recube kills O's gammons.

D/T

[Walt]

I don't know if it's QF at work, but everyone I've posed this to says
"double". (The take should be obvious to everyone so I'm not at all
surprised that everyone gets that part right.)

X has 13 shots that hit immediately; if he misses O leaves a blot to
shoot at 22/36 times. X wins almost all of the time when he hits,
adding up to about 45% GWC. The first time I encountered a situation
where it was correct to double at less than 50% GWC it surprised me.

I was hoping someone would point out that X is less than 50% to win but
it is nonetheless to double because of.... But since no one did, I'll
have to do it myself.

We are all familiar with the concept of raw takepoint, which is computed
as risk/(risk+gain). There's a similar concept, the minimum doubling
point (MDP) , which is calculated basically the same way. But the MDP
is more theoretical than the takepoint since you usually need to be
somewhat above the MDP for a double to be correct due to the cube vig,
opportunity cost of not being able to double later when the cube is more
efficient, and the lack of market losers. Think of MDP as the lower
limit of when it would ever be correct to double (ignoring gammons).

So, what's the MDP here? At any even match score, the MDP is 50%. You
need to be at least the favorite to cube. When behind in the match,
your MDP can sink below 50%. Here at 5a 3a:

If you double and win, the difference is between 3a 3a (50%) and 3aC
(75%) for a "gain" of 25%. If you double and lose, it's the difference
between 5aC (15%) and match over (0%) for a risk of 15%

risk/(risk+gain) = 15/40 = 37.5% So, X's doubling window opens at 37.5.
He's well within that, and the 13 market losers mean the time to strike
is now.

OTB, I didn't think about this, I just lazily saw that I was less than
50% and held. Holding is a .1 error.

XGID=-ABCBCB------------ba-dBf-:1:1:1:00:0:2:0:5:10

X:Player 1 O:Player 2

Score is X:0 O:2 5 pt.(s) match.
+13-14-15-16-17-18------19-20-21-22-23-24-+
| | | O O O X O |
| | | O O X O |
| | | O O |
| | | O O |
| | | 6 |
| |BAR| |
| | | |
| | | |
| | | X X | +---+
| | | X X X X X | | 2 |
| | | X X X X X X | +---+
+12-11-10--9--8--7-------6--5--4--3--2--1-+
Pip count X: 95 O: 35 X-O: 0-2/5
Cube: 2, X own cube
X on roll, cube action

Analyzed in Rollout
No redouble
Player Winning Chances: 45.49% (G:0.00% B:0.00%)
Opponent Winning Chances: 54.51% (G:4.73% B:0.03%)
Redouble/Take
Player Winning Chances: 46.09% (G:0.00% B:0.00%)
Opponent Winning Chances: 53.91% (G:6.88% B:0.06%)

Cubeless Equities: No Double=-0.134, Double=+0.099

Cubeful Equities:
No redouble: -0.004 (-0.103)
Redouble/Take: +0.099
Redouble/Pass: +1.000 (+0.901)

Best Cube action: Redouble / Take

Rollout:
1296 Games rolled with Variance Reduction.
Moves: 3-ply, cube decisions: XG Roller
Confidence No Double: � 0.003 (-0.007..-0.001)
Confidence Double: � 0.004 (+0.095..+0.103)

Double Decision confidence: 100.0%
Take Decision confidence: 100.0%

Duration: 1 minute 42 seconds

eXtreme Gammon Version: 2.10, MET: Kazaross XG2




--
//Walt

[Tim Chow]

On May 6, 10:28 am, Walt <walt_ask...@yahoo.com> wrote:
> I don't know if it's QF at work, but everyone I've posed this to says
> "double".

It's definitely QF at work. I usually don't miss these OTB any more
but I certainly used to and I know lots of other people do too. Even
if you understand the principle, all you have to do is forget for a
moment what the score and cube location are and the opportunity will
blow right by you.

---
Tim Chow