Game 4, move 30 : Forum 4-2

[diane]

Forum, blue to move 4-2.

8fYHACA228ACGA:QQmqACAACAAA

[dorbel]

Spoiler

Not very difficult, Blue needs to spread a net in the outfield to catch that straggler if he can jump out. I like 13/9, 13/11, which gives us 31 shots on the 17pt and 21 on the 15pt. 14/12, 13/9 does minutely less well, 30 shots and 21.
14/10, 13/11 gives 30 shots and 27, which is best of all as far as that goes, but it duplicates a lot of return shots if the straggler can jump and hit. I doubt if there is much between any of these, so I selected 13/9, 13/11 because it keeps the man on the 14pt. It's usually best to have the last man as far back as possible.
14/8 has much the worst coverage, I can't like that. 13/7 is more interesting because White can't leave with a tempo, so you get double shots against three points, but it denies us the chance to pick up a second checker when he does hit the indirect and the spare on the 7pt just doesn't look right!

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[ah_clem]

Spoiler

We can't move the runners.  Hitting loose would be a blunder, as would moving any of the other checkers in/near the home board.

That  leaves shuffling the checkers near the midpoint.  13/7 has the advantage that it's completely safe from fly shots, and leaves a double shot if blitzy tries to run his backman.  The disadvantage is that it's rather passive.  If we could bring two checkers into range of the four point I'd do that, but we can't.  The other shuffling plays don't seem to offer enough of an advantage to make up for the fly shot.  Of course, we're talking ablut a 1/18 chance, and we have good counterplay with his blot on the ace point so the other plays are probably fine.

13/7

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[ah_clem]

Spoiler

Where is this going?   I'm trying to visualize what we're going to do next and how our current play interacts with that.

There are two things we'd like to do: make the 4 point, and escape our runners.  Meanwhile, we'd like to maintain outfield control to catch an escapee.  If we can bring both runners out next move, that would be a great step forward - better outfield control, and we can't make the four point while maintianing outfield control unless we get more men in position.  The thing is, we probably won't be able to move both, and since we don't want to move our outfield checkers further in, we'll probably be playing one checker off the 23 next roll. 

Since we're about to do something risky (not very, but there's the chance to be hit and dance and then have blitzxz get lucky and mop up our blots) I like the idea of one less blot hanging around.

I don't have the aesthetic eye to see how the spare on the 6 "looks wrong" - it seems well poised to move to the 4 point, hitting loose if necessary to contain the runner, while being safe itself. 

All this being said, I doubt that there's much equity difference between the moves.  13/7 is very much the "obvious beginner" move and sometimes I tend to shy away from those in favor of something more "interesting" , but sometimes the obvious beginner move is the right one.

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[dorbel]

Spoiler

Fair enough. Why does the checker on the 7pt "look" wrong. Because if the straggler stays where it is, it gives us one number, 3-3, to make the 4pt next turn. If we play 13/9, 13/11 we get 4 numbers, 5-5, 5-3 and 3-3 to make it. Do we give up the bar to make it, even if it means leaving a shot. You bet we do!
What if White is able to get to the 4pt but not escape? If you play 13/7, then you have one number to make the point as we have seen and 17 other numbers (6-4, 6-3, 5-5, 5-4, 5-3, 4-3, 3-2, 3-1 and 2-1) to hit loose. If we play 13/9, 13/11 then we have 4 numbers to point on his head as we have seen and another 24 numbers (6-5, 6-4, 6-3, 6-1, 5-4, 5-2, 5-1, 4-3, 4-1, 3-2, 3-1 and 2-1) to hit loose. It's no contest. However I didn't do all this before deciding that the spare on the 7pt "looks" wrong, I can just "see" that it is, just as I can see that playing to dodge an indirect shot when we get a hatful of returns at it anyway is wrong. The sequence that ah_clem is trying to avoid by not leaving an indirect shot (hit/dance) requires a 2/36 x 9/36 parley, 18/1296 or a 1.4% chance. So 1.4% we regret it, 98.6% we don't.
There is another string where we are happy to have three builders in the outfield. If White gets to the 4pt, we will switch points with 1-1 and 2-2, after which we have three builders aimed at the missing point, rather than 1.

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[stog]

Spoiler

nice one! i am persuaded- and have added 'remove vote' for others

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[ah_clem]

Spoiler

Thanks. This is the kind of explanation that you never get from a bot rollout. 

One key idea is that it's advantageous to abandon the bar point to make the four point - I've been getting dinged a lot lately for making similar errors.  Once you see that the bar point is in play to make the four, it's clear that 13/7 is inferior since your play offers so many more possibilities to make the four.

From another perspective, recall Magriel's "safe vs bold" criteria.  Here 13/7 is safe, while spreading them around is bold.  We're behind in the race, behind in the match, have more checkers back, have more homeboard points, plus he has a blot in his homeboard.  All these point towards bold play.

So I'm on board with the spread 'em around ruse.

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