Problem of the Week #29: September 20


Cash game. Center cube. Black on move.




Black to play 6-4.

my gut is telling me to do something with the spare checkers on the 24, 8 and 6 points, but i think i'd end up going for 20/10 as the optimal move. yeah we break our defensive anchor on the 20 point, but our checkers on the 18 point are somewhat stopping him from doing anything fancy with his ones on the 17 and 14 points. moving the 6 and 8 point checkers seems too early to do just yet.

20/10. Breaking the defensive five point isn't that big a loss because the five and bar points are redundant. Black's best strategy is a priming game, trying to contain White's back checkers, so it's imperative he makes his offensive bar point (or the 5 point, but the bar would be better of course) as soon as possible. He needs to bring builders around to achieve that.

Making the two point is worse than useless, it doesn't form part of any coherent strategy for winning the game. It buries checkers where they aren't needed and strips them away from their current position as builders.

Looks to me like one of those proto-backgames that Bill was talking about. Circulate checkers and control the outfield seem like important themes. Ideally, we'd like to move the back checker on the 24-point, but that would leave us with 8/2 as our only viable 6, which looks pretty bad.

Like ChrisV said, it isn't that much of a loss to leave the defensive 5-point since we also have the bar point anchor.

20/10.

Agree, 20/10.

I agree 20/10.

I don't like 20/10, you're giving up white's 5 point and getting nothing in return. If white starts getting some good rolls, you can get screwed over pretty badly.

There's only one move I see that doesn't kill any checkers or give up key points:

24/18, 10/6.

If white gets an opportunity to hit the blot on the 10 point, he will probably have to leave the blot on the 4 point (barring a 6-6).
White doesn't have a strong home board yet. With any luck, you should be able to either avoid getting hit or be able to feast on the blot on the 4 point.

Why take this risk, though, if you don't have too? I understand your reasoning, but I disagree. Your move breaks a key blocking point at this stage of the game. Also, despite the fact that the defensive 5-point is most often a key point, the fact that you already have an advanced anchor and the lack of alternative probably makes this an exception.

White doesn't have a threatening board right now so we can afford to leave the golden point. Also, you might be able to re-anchor there, who knows.

The 10 point is a massive point for you. It's probably the most important point you hold on the board. White's potential hits on the blot aren't really the problem, the problem is giving up the capability to prime White's back checkers, which is the major way you should plan to win the game. I would take 24/18 6/2 over that play easily.

20/10 and 24/18 - 20/16 are by far the only soluntions. No sense to put chekers behind enemy lines....
Between those i would chose the second one beacause gives me more flexibility. I don' t really care at the moment being hitted , and eventually give away the golden point, since i own the 18 point.
20/16 - 24/18 , by far ...

Don't really get that. You've still broken the 5 point, but you've failed to bring any builders to help fill up the broken prime. Also you've left heaps more hits. I don't see what the advantage is compared to 20/10. You said "flexibility" but I don't see why the position is more flexible compared to 20/10.

Interesting. I must admit that I hadn't thought about that one...
White might be more inclined to hit loose on his 5-point with that move, but it's not really a big deal I guess.

Good point, our bar point isn't made yet, so I still prefer 20/10. Plus, since we're behind in the race, we keep maximum contact by letting the straggler on the ace point.

You make a good point.
I figured that you'd still be able to prime the back checkers if he takes a shot at the blot on your 10 point.
I dunno, I've been burned so many times by breaking an anchor. I hate giving up an anchor on key point like my opponent's 5 point.
But maybe the 10 point is the most important point in this position.
I guess we'll find out in about a week.

20/10

White's position is very brittle and you're going to have a decent chance at having a blot to shoot at in the next roll. Keeping the checker on the 24 point maximizes the number of shots you'll get without much risk. Your 20 point anchor isn't all that valuable right now since you've got the bar point AND most of your checkers are tied up in your prime AND white will not want to hit loose here and risk having a third checker put behind your prime.

I'm such a wuss that I looked at the problem and immediately thought 24/18 6/2.

This feels a lot like selective memory. Think about all the times you've held an anchor and been squeezed off it at some inopportune time because you didn't leave sooner. Or the times you've left the anchor and come around safely. Or the times that an opponent has abandoned an anchor and gotten away from you.

A more helpful approach would be to contemplate the following questions:
When things went badly for you after abandoning an anchor, WHY did it go badly? What were the circumstances surrounding that decision? What did the structures look like (home boards/blots/outfield points)? Where were you in the race?

Thanks for the suggestion.
I'll pay more attention to the circumstances next time I have this decision to make and I'll try to be more objective.
If I break the anchor and it goes bad, I'll try to figure out exactly what went wrong.

20/10 is the only move that avoids premature burial and/or dismantling blocking points; here, white has a weak board, only one spare for the 5pt, and black has another defensive anchor anyway-- it's really not that risky breaking the 5pt.

I think in general, when you're forced to choose between an ugly premature burial and breaking a defensive anchor, breaking anchor is usually right; the exceptions tend to be some combination of a) being under extreme threat, or b) winning by playing forwards is hopeless.

The Value of an Outside Prime
To paraphrase Robertie's Advanced Backgammon Problem 182: An outside prime is virtually useless in blocking a single point held by your opponent. The value of an outside prime is a blocking a large mass of your oppenent's men.

Is This a Two-Way Holding Game?
There are two strategic approaches to this problem as I see it. The first is to view it essentially as a two-way holding position. In this light, Black will have trouble holding on to his outside prime. He'll have even more trouble holding on to his two high anchors. He simply doesn't have enough checkers for all that. Tacticly, then, Black would like to give up one of his advanced anchors. Later on, as the game morphs into a more traditional two-way holding game, he should plan on relinquishing one or two of his outside points, trading them for his five point, and perhaps his bar. A two-way holding game is one of the few game plans where it is correct to make points behind your opponents anchor; Black should plan on that as well.

In this light, two plays seem possible: 20/10 and 8/2, 6/2. As it's a bit too soon for the former, I would play the latter.

Is This a High Backgame?
The second possibility is to view this position strategically as an unusual "high backgame". With this idea, Black tactics should be to keep his men in play in front of White, taking advantage of the ease with which he can recirculate his checkers. With this plan, Black should hold onto his two anchors until a decisive hit occurs. The only constructive play I see is to slot his five point, leaving two blots: 24/18, 9/5. Black should resist the temptation to kill a checker by passing White's anchor.

My Preference
Although it seems a bit obvious, I would play for a two-way holding game, by abandoning the golden point now.

20/10

For the Record
I've been answering these problems without the use of a bot since problem 28. My record at this writing is a meager 50% correct.
Correct: 28(a)
Incorrect: 28(b)

Seems a bit contradictory, no?

Thanks, UberKuber, for the correction. I meant to say, "As it's a bit too soon for the latter, I would play the former."