Doubles: Bill & Steve versus Dmitriy and Prince

Below are selected error from Novi doubles match. Steve and I against Dmitriy and Prince.

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Opening game of 7 point match. 11 to play.

is Dmitriy and Prince score: 0 pip: 159

7 point match

pip: 159 score: 0 is Bill and Steve

XGID=-b-B--D-B---eE---b-bbb--B-:0:0:1:11:0:0:0:7:10

to play 11

1.	XG Roller++	24/22 6/5(2)	eq: -0.131
	Player: Opponent: 46.44% (G:14.12% B:0.74%) 53.56% (G:15.69% B:0.71%)
2.	XG Roller++	8/7(2) 6/5(2)	eq: -0.189 (-0.058)
	Player: Opponent: 45.46% (G:14.18% B:0.79%) 54.54% (G:17.77% B:1.03%)
3.	4-ply	24/23(2) 6/5(2)	eq: -0.250 (-0.119)
	Player: Opponent: 42.94% (G:13.13% B:0.59%) 57.06% (G:16.11% B:0.77%)

eXtreme Gammon Version: 2.02, MET: Kazaross XG2

We didn't really give this play any thought.

8/7(2), 6/5(2) was out play, blocking sixes and forming a broken four prime.

Better was 24/22, 6/5(2). I am guessing reasons are:

Bar is not a new point. Opp's 6-5-4 structure is very strong and we should try to split now while they lack checkers in the zone.

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We trail 7 away 6 away. We have already cubed and have 65 to play.

is Dmitriy and Prince score: 1 pip: 116

7 point match

pip: 125 score: 0 is Bill and Steve

XGID=-bBB-BC---C--A---cbb-dB-b-:1:-1:1:65:0:1:0:7:10

to play 65

1.	XG Roller++	10/5 10/4	eq: +0.376
	Player: Opponent: 65.93% (G:22.05% B:0.75%) 34.07% (G:10.12% B:0.34%)
2.	XG Roller++	13/2	eq: +0.315 (-0.062)
	Player: Opponent: 63.21% (G:20.17% B:0.65%) 36.79% (G:6.77% B:0.19%)
3.	4-ply	13/8 10/4	eq: +0.318 (-0.059)
	Player: Opponent: 64.14% (G:19.61% B:0.69%) 35.86% (G:8.53% B:0.24%)

eXtreme Gammon Version: 2.02, MET: Kazaross XG2

We played super wimpy 13/2.

Better was to slot 13/8, 10/4. The twin tactical themes here appear to be:

Keep you checkers in play; don't kill them.

Opponent's position is realatively weak, so the cost of getting hit is less than it might otherwise be.

Strategically, it looks like we are trying to outprime him, so slotting makes more sense in that context also.


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Later in the same game. We have a tricky 32 to play.

is Dmitriy and Prince score: 1 pip: 110

7 point match

pip: 110 score: 0 is Bill and Steve

XGID=aABB-BCAa-B------cbb-dB-b-:1:-1:1:32:0:1:0:7:10

to play 32

1.	XG Roller++	10/8* 8/5	eq: +0.785
	Player: Opponent: 74.48% (G:38.99% B:0.64%) 25.52% (G:6.20% B:0.24%)
2.	XG Roller++	10/7 10/8*	eq: +0.747 (-0.038)
	Player: Opponent: 74.09% (G:35.74% B:0.64%) 25.91% (G:5.45% B:0.19%)
3.	XG Roller++	7/4 6/4	eq: +0.663 (-0.121)
	Player: Opponent: 70.91% (G:35.23% B:0.64%) 29.09% (G:6.13% B:0.22%)
4.	XG Roller++	6/1	eq: +0.639 (-0.146)
	Player: Opponent: 69.26% (G:36.54% B:0.46%) 30.74% (G:5.63% B:0.20%)

eXtreme Gammon Version: 2.02, MET: Kazaross XG2

At least four reasonable options here.

We went with 7/4, 6/4 making the board. It worked out for is, as we eventually close dout two checkers and rolled hime to a gammon. But any ace is really bad, and even if he misses we are nine long pips away from covering next time.

Worst was 6/1. This makes a 5 point board without a blot. But the board with hole on 4 point is much weaker than hole on ace point. If Dima&Prince enter from the bar timmediately we are in big trouble and if they enter within a few rolls hey are right back in the game.

The top play per the computer was 10/8*, 8/5. This hits a second blot and diversifies our men best for filling in the ace, four points.

Second best was 10/8*, 10/7 which also hits a second man but is less efficient in the aim to closing the board.


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We lead 3 away 6 away and have 36 to play from the air.

is Dmitriy and Prince score: 1 pip: 165

7 point match

pip: 151 score: 4 is Bill and Steve

XGID=-aaB--DaC--BbB-b-c-e----AA:0:0:1:63:4:1:0:7:10

to play 63

1.	XG Roller++	Bar/16	eq: +0.099
	Player: Opponent: 55.61% (G:18.64% B:1.00%) 44.39% (G:11.78% B:0.50%)
2.	XG Roller++	Bar/22 24/18	eq: +0.078 (-0.022)
	Player: Opponent: 55.28% (G:18.71% B:1.20%) 44.72% (G:12.31% B:0.51%)
3.	XG Roller++	Bar/22 13/7*	eq: +0.031 (-0.068)
	Player: Opponent: 53.64% (G:19.95% B:1.33%) 46.36% (G:12.36% B:0.69%)

eXtreme Gammon Version: 2.02, MET: Kazaross XG2

We entered and hit with Bar/22, 13/7*. While we have the better board, this play seems too unlikely to work. We get back with most 1's, 5's and 6's. Probably we did it because we didn't want to give opponents a free chance to anchor on the bar point.

But stategically, we are up in the race so moving the back men makes sense. Either Bar/16 or Bar/22, 24/18 are better plays. They can't do everything in one roll and with the better board, an exchange of hits may favor us.

Another small factor may be that hitting gives up the midpoint and strands our back men somewhat.

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We are on roll holding a 2 cube and leading 3 away 6 away. Cube action?

is Dmitriy and Prince score: 1 pip: 3

7 point match

pip: 5 score: 4 is Bill and Steve

XGID=-AB---------------------c-:1:1:1:00:4:1:0:7:10

on roll, cube action?

Analyzed in XG Roller++	No redouble	Redouble/Take
Player Winning Chances:	85.65% (G:0.00% B:0.00%)	85.65% (G:0.00% B:0.00%)
Opponent Winning Chances:	14.35% (G:0.00% B:0.00%)	14.35% (G:0.00% B:0.00%)
Cubeless Equities	+0.713	+1.169
Cubeful Equities
No redouble:	+0.713 (-0.092)
Redouble/Take:	+0.805
Redouble/Pass:	+1.000 (+0.195)
Best Cube action: Redouble / Take

eXtreme Gammon Version: 2.02, MET: Kazaross XG2

We rolled. It turns out this is a large double. I had a similar position a couple weeks ago where I was up 3 away 7 away holding a 2 cube in a 3 roll position. That time I redoubled to put the match on the line and it was a huge error. So, I was gun shy and overcompensated this time, which turns out to be a proper cube. Note also I goofed up the big cube against Ray (prior post) so I need some work on these.

Let's look at the math.

Min Double Point = Risk / (risk + gain)

= [ (No Double & Lose) - (Double & Lose) ] / [(Double & WIn) - ( No Double & Win) + RISK]

= [ (ME 3a4a) - (lose match)] / [(Win match) - (ME 6a Crawford)+ RISK]

= ( 57 - 0 )/ (100 - 89) + 57

= 57 / 68

= 84%

A two roll position is about 86% to win. Though here double ones don't get off, so that should cost a bit, maybe a percent. So let's say we are 85% to win. Therefore, I guess it is a small double.


However, I am absolutely hopeless when it comes to this stuff. It took me twnety minutes with a calculator in hand to come up with this 84% number. I have zero chance of doing this at the table.



Let's try another approach. What is opponent's takepoint? Dmitriy and Prince can drop and play from 6 away Crawford - about 11%.

Or they can take and rewhip for the match, when they are a tiny bit better than a two-roll position. I woudl hvae estimated 15%.

So we know the position is an easy take. But is it a double? This is the tough part. This is like a "last roll" as far as the cube goes, since next turn the game will either be over or they are dropping. So we lose the market on the next exchange if things go well.

The key seems to be how close is opponent to the drop point? ie, how close are the winning chances (15% in my head, actually 14%) to the drop point (11%)?

The closer to the drop point, the more efficient the cube, and the further away the less efficient. Realistically, this is the best I can hope to achieve over the board. Figure out opponent's drop point, estimate win chances, and note the gap betweeen the two and that make a judgment call. Given all this data, I still would have held the cube as the four percent gap from 15 to 11 seems large enough that you are risking too much for not enough gain. But I guess it is a double after all.