Playing Doublets Part II
Hello again, Doublet-Master here
Last time we'd elaborated on the method to deal with these tricky bugs.
Then, for the sake of simplicity we'd left out of our analysis factors like match score, cube position, gammons. Now we're going to see an example where these factors do weigh in the situation so that it turns advisable tailoring your play accordingly.
The following position was brought to us in rec.games.backgammon, the backgammon newsgroup, by a controversial character from there, our fellow Monty.
Black (you) is on the bar and has to play 11, he moves counter-clockwise (from 24 to 1). After the obvious: bar/24, the analysis goes on to the remaining three moves.
On a first attempt, we'll use the method explained last time in a general way, assuming the simplest game condition -- a 1-point game. On a second attempt, we'll compare the main alternative plays available, over different game conditions and see whether their relative merits change.
So you ask yourself the three questions:
A: What's your top priority goal in the current situation?
B: Which is the first one(s) out of the three aces to move, that best fit your top goal?
C: What's the most efficient use of the remaining moves?
Since you're under the gun and will likely be attacked back there, you should move the last ace so that you could retain as strong a board as possible on the next turn.
Many of you will be surprised to know that the move that best accomplishes this goal is: 6/5!
Excuse me...?! As strong a board?! Yes -- had you played 4/3 or 3/2 or 2/1 and get attacked, you'll use one die to enter and the second die to jump out if you got lucky ...or else have to give up a second inner point!
The other way, 6/5, you'll safety one of your inner blots, leaving only one exposed and retaining a 4-point board. Paradoxical isn't it?
Conclusion: in a general way, best play is: bar/22 6/5.
Now let's see how diverse game conditions may effect the relative value of the various plays available. For these evaluations, I've used a Snowie 3-ply evaluation (no rollout), so please excuse any inaccuracy you could eventually find by doing a rollout yourself. What matters is understanding how the reasoning goes.
Scenario # 1: Moneygame, Score: irrelevant, Cube: any value and side, Jacoby rule in effect.
Scenario # 2: 3-point match, Score: 0-0, Cube: 1
Scenario # 3: 5-point match, Score: 0-0, Cube: 1
Scenario # 4: 5-point match, Score: 0-0, Cube: 2 (either side)
Scenario # 5: 3-point match, Score: you lead 2-0 Crawford, Cube: 1
Scenario # 6: 3-point match, Score: you lead 2-1 Crawford, Cube: 1
Scenario # 7: 3-point match, Score: you trail 0-2 Crawford, Cube: 1
Scenario # 8: 3-point match, Score: you trail 1-2 Crawford, Cube: 1
Well, enough for today. You're left the homework of rolling out some of these scenarios and seeing for yourself how the key plays get ranked up and down over the changing conditions.