2-2 Is Often the Toughest To Play

[Simborg]

I have thousands of positions saved in my database of tough plays. It's amazing how many of them are 2-2. You just have so many ways to play this number. Here is one I played wrong yesterday.

Double Match Point, Black to play 2-2





The key to this position is getting your two back checkers out of White's inner board before you have to crack your board. So you need to get a couple of 5's before you either crack or he comes in and gets out of your trap.

There is little question that we must hit. To me, the question was whether to hit loose (with one checker) or make the ace point. Hitting gives you more time to get your checkers out, because if White comes in with one checker and you do roll a 5, he can hit that checker or start attacking the one you have left. If he's on the bar, then you have a better chance to get both checkers out safely.

I made the error of switching points. There are three reasons this is the wrong play: first, if he comes in on the 3 instead of the 1, it is easier for him to escape. Second, if you hit loose and he doesn't hit you, you stand a good chance to close your board and not have to worry about him at all...so if you get a 5, you have more time to get the second checker out without worry about him attacking you. Thirdly, if you hit loose and he hits you, that's not so bad. You might come in on his 1 point, and then you would have both 6 and 5 to get out without cracking your board. Or you might dance (fail to come in) for a while, and he might come in with a 1, fail to get out of your board, and have to move his checkers off the 8 point, allowing you more room to get out. So whether you get hit or not, you are better off slotting the 1 point than making it.

[puzzle_t0rico]

Great example that shows me why I always play bad this situation.
Thanks for explaning me why it was bad.
Though, I do not completely agree (but I suck at BG) with Snowie about the best move: 7/5-7/1*
I prefer the second one because it allows to cover with one more number.
I explain myself. If we do 7/5-7/1* we can make the ace point with 5's or 4's if we are not hit (25/36 of the time) which is 20/36 of the time (so, 500/1296, not bad)
Though, I'd rather prefer to use the 5's to bring the last men than to make the ace to not break my inner home. So, I am losing 9 combinations out of the 20.
If we do 7/1*-6/4 we can cover the ace point with 3's and 6's (20/36 again) and we leave the 5's to escape. So, we do not loose combinations.
Please tell me what it is wrong in my reasoning.
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If the brain were simple enough to be understood, we would be too stupid to understand it.

[Simborg]

The best analysis I can give you, and it covers your point, which is a good one, comes from one of the best players in the world who I asked to analyze this play, Perry Gartner:


There is one reference formula and one concept that I use to solve such problems.
The RF - With each side needing 11 numbers the side that is on roll achieves it first 60%(appx.) of the time. In the current position you need 11 numbers to escape (technically only 9 escape for you as 5-1 doesn't). Further, you both need to perform with 2 checkers but it will most often boil down to 1 unless you roll the one double that brings both out from behind the prime or in from the roof.
In this position you need to roll two 5 's and he needs to roll two 1's or 3's depending on your play but he is on roll. You might ask if he comes in first why does Snowie say you are a favorite? That's because you have other positive play options even when you do not roll a 5. You can close him out, hit and pass and switch again. He on the other hand cannot move until he comes in and has more to do than merely come in. He has to contain one of your checkers. If he anchors before you get out he still loses out when you have a blot on his 2 point, he hits loose, you hit back and escape before he can solidify his position. You also have more to do if you don't close him out but I cover that in the concept discussion. The point here is that a significant percentage of the time he will be in play before your 2 checkers are out, as your other play options are somewhat limited since you don't have that many builders left.
For this reason hitting loose becomes a more desirable option as hitting loose is the easiest way to a closeout. If you only had one checker back the right play would be to switch as you have more time to get out.
Concept- If you need to hit, the longer your prime is the more trouble he will have escaping once he gets in. The difference between 11 numbers to escape a 5 prime vs 20 to escape a 4 vs 27 to escape a 3.
In your position note it is 11 vs 27 unless you can remake the bar some how and then it would be 11 vs 20.
The bottom line is that by hitting loose on the one you raise the performance level of what he has to do to take an advantage. He has to hit back and bring 2 checkers out. You give yourself close out opportunities and make life tougher for him if you can't close him out. In this variation when you are hit back with a 1 you can survive longer. When he enters first on the 3 point and you are still back in his home board, you will likely hit him loose on the 3 to keep him from anchoring. Getting hit on the 3 is far worse than getting hit on the 1.
Interesting that after hitting loose on the 1, Snowie chooses not to un-duplicate it's escaping number. A checker could move 6 to 4 with the 2, giving 6's and 3's to cover instead of just 4's to cover as the 5 escapes rather than makes the 1 point if one checker hasn't escaped yet.. Snowie doesn't want a blot sitting on the 7 point when its opponent anchors up, with Snowie on the roof. You might think this an unlikely variation but it happens often enough to impact the play because your covering numbers off the bat are not many.