Problem of the Week #145: June 18


(a) Money game, center cube.




Should Black double? Should White take if doubled?


(b) Same position, money game, Black owns a 2-cube. Same question.

(c) Same position, center cube, Black leads 1-0 in a match to 5. Same question.

(d) Same position, center cube, score is 1-1 in a match to 5. Same question.

(e) Same position, center cube, Black trails 1-2 in a match to 5. Same question.


Note: All ‘cash game’ problems assume the Jacoby Rule is in effect. That is, you can’t win a gammon unless the cube has been turned.

I'll learn something this week. I have NFI what's going on, but I'm not really inclined to give up the cube in b. The edge can't be that big yet and gammons are already on. I'll answer that one ND/take and leave the rest.

a and b) no double/take
4 away with more gammons against me= double. Itake c and d and as much as I hate it drop e. Down 3-2 seems better than putting match on the line.

a) no double/take
b) no double/take
c) double/take
d) double/take
e) double/drop

If you see any backgammon players in Vegas tell them there's a new problem up.

Grunch!

It is a bit late to be answering this — Bill has already published the solution — but I want to take a stab at it anyway. I have been meaning to work up doubling windows, take points, and so on, but it just never happened. Today, I’ll just give my seat-of-the-pants answers. I have not yet read the solution.

(a) Money game, center cube.

In favor of doubling: if Black fails to enter, White will turn the cube anyway. If Black hits, there are a few market losing sequences, perhaps, for instance, when White dances, or cracks by rolling 44.

If Black is planning to take White’s double later, he may as well double now, and get the advantage of his hit. On the other hand, if Black is planning to pass White’s double, then he should not cube this.

Note that this is a trivial take for White. 30% of the time, Black will fan, and then White is in the driver’s seat.

Me? I’m taking later, so now:

Double/take

(b) Same position, money game, Black owns a 2-cube. Same question.

Now White cannot cube Black after a Black dance, so Black should hold onto the cube.

No double/take

(c) Same position, center cube, Black leads 1-0 in a match to 5. Same question.

Black should protect his lead in this volatile position. I would not double.

No double/take

(d) Same position, center cube, score is 1-1 in a match to 5. Same question.

As Black is more likely than White to lose a gammon here, he should not double. Were he to double, losing a gammon would mean losing the match.

No double/take

(e) Same position, center cube, Black trails 1-2 in a match to 5. Same question.

When Black doubles and wins a single game, the match score becomes 3-2 in his favor. If he doubles and loses a single game, the match score becomes 1-4 Crawford against him. And if he doubles, and then loses a gammon, he will lose the match.

Note that after a Black double, and a take by White, the cube is essentially dead. That is because White should play for a gammon after a Black dance, rather than redouble.

As he trails in the match, and a take by White lessens the value of a gammon victory by White, Black should double.

Double/take

For the Record
I am so often wrong that I like to post my record in these messages. It's kind of a truth-in-advertising thing. Grunch: I have been answering these problems without the use of a bot, and before checking the excellent solutions of others, since Problem 28. My record at this writing is 54%.