The best book Robertie never published

As you know, my interest in studying ebbs and flows.  I haven't blogged much due to work, family and other interests.  But I am still studying and playing a bit, and will probably blog more in the future.

I recently discovered a treasure trove of annotated problems by Bill Robertie.  There are about 150 problems of the week going back a few years.  This is where my limited study time has been directed lately.

Robertie's explanations are excellent, and I would encourage everyone to check them out.  http://forumserver.twoplustwo.com/138/backgammon/

Phil's advice

From a recent video by Phil Simborg.

proper thought process for checker plays:

1) Identify your gameplan (race, prime or hit)?

2) Find a play that best fits that gameplan


Simple.  Brilliant!! 

How often do we grab the checkers and make the first move we see?  I know I do it too much.  And while sometimes tactics trump strategy I really love this advice.  I will try to follow this going forward.

brucewayne

Below are selected errors from an online match against brucewayne.

***********
First game of 7 point match and I am on roll.  Cube action?

is brucewayne score: 0 pip: 151

7 point match

pip: 151 score: 0 is Chutzpah

XGID=-b----EBB-A-cC-a-c-d-Bb---:0:0:1:00:0:0:0:7:10

on roll, cube action?

Analyzed in XG Roller++	No double	Double/Take
Player Winning Chances:	63.11% (G:18.42% B:0.88%)	63.25% (G:18.57% B:0.89%)
Opponent Winning Chances:	36.89% (G:8.11% B:0.30%)	36.75% (G:8.13% B:0.30%)
Cubeless Equities	+0.374	+0.775
Cubeful Equities
No double:	+0.571
Double/Take:	+0.492 (-0.079)
Double/Pass:	+1.000 (+0.429)
Best Cube action: No double / Take
Percentage of wrong pass needed to make the double decision right: 13.5%

eXtreme Gammon Version: 2.02, MET: Kazaross XG2

I doubled and brucewayne took.

A pointless double.

While I have a definite advantage (I have the better anchor and start of a possible prime plus some threats to hit), I am outboarded and have a lot to accomplish yet before the game moves to the drop zone.  I think the key is that I don't have any home board points yet, hence the term "pointless double."  A good rule of thumb is never make a pointless double, and this appears to be no exception.

************
Same game.  I have already doubled.  How to play 63?

is brucewayne score: 0 pip: 135

7 point match

pip: 167 score: 0 is Chutzpah

XGID=aAA--BCaC---aaa--b-dbBbBA-:1:-1:1:63:0:0:0:7:10

to play 63

1.	XG Roller+	21/12*	eq: -0.481
	Player: Opponent: 41.95% (G:16.34% B:1.97%) 58.05% (G:28.51% B:3.43%)
2.	XG Roller+	24/21 8/2	eq: -0.545 (-0.064)
	Player: Opponent: 39.10% (G:14.76% B:1.47%) 60.90% (G:24.14% B:1.41%)
3.	XG Roller+	21/18 8/2	eq: -0.575 (-0.095)
	Player: Opponent: 38.08% (G:17.34% B:2.46%) 61.92% (G:31.78% B:3.66%)

eXtreme Gammon Version: 2.02, MET: Kazaross XG2

I was really baffled on this one.  The most optimistic play is simply hitting with 21/12*.  This turns out to be the best play.  I was reluctant to give up the security of the double anchor, but I guess you gotta go for it.

I played 24/21, 8/2.  This preserves timing and covers a blot, but ...  you really don't the two point anyway.  Perhaps most important, by hitting I hold out hope of winning the game going forward, while if he hits I have a good chance to remake a second anchor.  As a bonus, I get to recycle my guys from the deep ace and deuce points.

*************
Later in the same game.  now we are in the containment phase.  How to play this 62?

is brucewayne score: 0 pip: 92

7 point match

pip: 143 score: 0 is Chutzpah

XGID=a-C-BBB---A---A-Ab-ceAbBb-:1:-1:1:62:0:0:0:7:10

to play 62

1.	XG Roller+	21/13	eq: -0.285
	Player: Opponent: 48.52% (G:5.66% B:0.17%) 51.48% (G:13.48% B:0.53%)
2.	XG Roller+	21/15 14/12	eq: -0.288 (-0.003)
	Player: Opponent: 48.42% (G:5.68% B:0.17%) 51.58% (G:13.55% B:0.52%)
3.	XG Roller+	23/21 16/10	eq: -0.457 (-0.172)
	Player: Opponent: 42.22% (G:4.44% B:0.14%) 57.78% (G:16.60% B:0.42%)

eXtreme Gammon Version: 2.02, MET: Kazaross XG2

I panicked, by moving 23/21, 16/10. This is a terrible play. I was thinking that I don't want to get stuck on the duece point but this is not a priority right now.

Top priority is containing the lone back checker. Therefore, any play which floods the outfield, eyeballing the escape zone from my 7-12 points is preferable. The best play is 21/13. This positions five checkers to guard the escape zone next roll.

Another concern may be that the two point is my last line of defense, so I should stay there just in case. However, since I have doubled him, this consideration may not apply in this case. If his straggler makes it home, brucewayne can always just double me out.

**************

Next game. I trail 7 away 5 away and am on roll. Cube action?

is brucewayne score: 2 pip: 123

7 point match

pip: 98 score: 0 is Chutzpah

XGID=--ABbBDBC---b----bAbbbc---:0:0:1:00:0:2:0:7:10

on roll, cube action?

Analyzed in XG Roller++	No double	Double/Take
Player Winning Chances:	64.84% (G:4.03% B:0.11%)	65.29% (G:4.05% B:0.12%)
Opponent Winning Chances:	35.16% (G:3.45% B:0.08%)	34.71% (G:3.81% B:0.13%)
Cubeless Equities	+0.305	+0.638
Cubeful Equities
No double:	+0.433 (-0.032)
Double/Take:	+0.464
Double/Pass:	+1.000 (+0.536)
Best Cube action: Double / Take

eXtreme Gammon Version: 2.02, MET: Kazaross XG2

True I lose my market if my back man escapes but I don't have too many rolls which make it home safe.  So I waited and held the cube.

Turns out this is a small double, and the reason appears to be the score.  I am not sure really why the score makes a such a difference, with gammons so low.  But apparently being behind is enough to push this to a clear cube. 

Compare to same position for money.

is Player 2 score: 0 pip: 123

Unlimited Game Jacoby Beaver

pip: 98 score: 0 is Player 1

XGID=--ABbBDBC---b----bAbbbc---:0:0:1:00:0:0:3:0:10

on roll, cube action?

Analyzed in XG Roller++	No double	Double/Take
Player Winning Chances:	64.99% (G:4.29% B:0.13%)	65.30% (G:3.89% B:0.11%)
Opponent Winning Chances:	35.01% (G:4.02% B:0.12%)	34.70% (G:3.47% B:0.09%)
Cubeless Equities	+0.303	+0.621
Cubeful Equities
No double:	+0.407
Double/Take:	+0.347 (-0.060)
Double/Pass:	+1.000 (+0.593)
Best Cube action: No double / Take
Percentage of wrong pass needed to make the double decision right: 8.4%

eXtreme Gammon Version: 2.02

*************
I trail 6 away 5 away and have 65 to play.

is brucewayne score: 2 pip: 135

7 point match

pip: 134 score: 1 is Chutzpah

XGID=-a-B--D-D-A-eB---bBc-aba--:0:0:1:65:1:2:0:7:10

to play 65

1.	XG Roller++	13/8 13/7	eq: +0.233
	Player: Opponent: 53.80% (G:14.16% B:0.36%) 46.20% (G:9.40% B:0.27%)
2.	XG Roller++	10/4 8/3	eq: +0.227 (-0.007)
	Player: Opponent: 53.52% (G:14.70% B:0.35%) 46.48% (G:10.73% B:0.31%)
3.	XG Roller++	8/2 6/1*	eq: +0.205 (-0.029)
	Player: Opponent: 52.42% (G:18.72% B:0.47%) 47.58% (G:14.99% B:0.56%)
4.	XG Roller+	13/7 6/1*	eq: +0.330 (+0.096)
	Player: Opponent: 55.41% (G:19.87% B:0.54%) 44.59% (G:13.58% B:0.72%)

eXtreme Gammon Version: 2.02, MET: Kazaross XG2

I moved 13/8,13/7.

Best was 13/7, 6/1*.  I think this play is right for a couple reasons.  First, brucewayne has two inner board blots. so I can be more bold than usual.  Second, by hitting on the ace point, he can't hit and escape at the same time.  With my play, his hitting sixes either and hit and cover or hit and escape.  Another factor may be that the 13/8, 13/7 play leaves my men stacked and positioned as awkward builders, while with the 13/7, 6/1* play they are better positioned to do something good next time.