Game 7, move 7 : Forum 5-3

[diane]

ok, after rkb's harakiri move...we have to find somewhere for our 5-3

Forum, blue , to move 5-3

tbkSATBs2w4AAw:UYmuADAAIAAA

[dorbel]

Spoiler

OK, I'll go out on a limb and break the prime, always certain to get a chorus of noooooooooo from the team in your chouette! White wants us to hit to try and keep some timing, I say we let him be and watch his board go down the tubes long before he gets a shot. For money, hit two men (and more later if possible) and go flat out for loads of gammons. Here we just want to win and note that we have to break the prime sometime anyway. 8/5, 8/3 for me.

[close]

[ah_clem]

Spoiler

A tough one.  We don't want to erode our prime. But we don't want hit him either.  And we really don't want to send two checkers back and allow him to make a second point in our board.

So, what to do?

We may regret it, but moving two checkers off the 8 point looks best.  Sure, we risk a disasterous 6-1, but I can live with that.  Hopefully, he'll be forced to move some of those blots out of the way and we can tiptoe past without hitting.  Meanwhile, we have 3 builders bearing on the 2 point, so we might be able to reestablish the prime.  Getting hit is not such a big deal as long as we maintain the blockade.

So, 8/5 8/3 is my best effort.

......

Scratch that.  Abandoning the prime is a blunder.  Hitting two checker is also a blunder.  Hitting one and moving a checker on the 8 is the way to go.  There are two moves that do this and I really don't see much difference between the two.  20/15*, 8/5 leaves threes to hit, 20/17*, 8/3 leaves 5s to hit.  But 33  allows us to play 8/2(2) so it doesn't have anti-jokers for us.  (55 isn't so bad with 20/17*, but not as good as 33 with 20/15*) So,
20/15*, 8/5

[close]

[socksey]

Spoiler

I want to get the most hits possible and save our prime by playing 20/15*/12*.  Unless he rolls a double 2, we will most likely pick up another one or 2 pips and still have plenty of room to cover our 2 pt.  Kill, kill kill is what I like. 

[close]

socksey



Power corrupts.  Absolute power corrupts absolutely.  But it rocks absolutely, too. - Lithograph from Despair.com

[ah_clem]

Spoiler

I want to get the most hits possible and save our prime by playing 20/15*/12*.  Unless he rolls a double 2, we will most likely pick up another one or 2 pips and still have plenty of room to cover our 2 pt.  Kill, kill kill is what I like. 

Socksey,

Kill kill kill is great for money play or when gammons count.  But gammons don't count here and frankly his best game winning strategy is to make a second point in our home board.  He can't do that with only 3 men back, it takes 4.  I wouldn't send the fourth man back here.

Dorbel,

ack.  Now I'm completely confused.  I first wrote an argument why eschewing the hit and breaking the prime is the right thing to do, then decided that sage players wouldn't give up the prime at this stage of the game.  In fact, I anticipated your next post telling me how wrong it is to abandon the prime.  But instead of telling me that I was wrong, you're telling me that I was right but that I was wrong to anticipate you telling me that I was wrong.   My head hurts.

Let's look at it again:

With 8/3 8/5, unless he rolls a 6 or big doubles, he'll likely leave the blots sitting there for us.  We might get a second play off the eight and be able to sit tight on our anchor, or we might be able to miss his blots with a 4 or a 6.  5s are bad for us, most doubles are bad for us, but there are lots of playable numbers.  If we can manage to not hit him, we should be able to waltz home while his board crunches.  The 6-1 joker is a factor here, but even if he does roll the joker, we'll probably enter and likely send another checker back in the process.  Even if we don't send a second checker back, he still has a checker stuck behind a blockade so he really needs two 6-1s to get away.

OTOH, hitting one checker and playing one off the 8 allows him to sit on the bar and wait for a shot while his board (such as it is) stays intact. He retains the ace point, and his timing will be good - as a general rule, a well timed ace point game gives about 25% chance of winning.  And if he can hit us, he might force us to send a second checker back. Then we're into a complicated backgame. ugh.

So, it seems like there's more to go wrong with the hitting play than the prime-breaking play.  I'm reluctantly going to withdraw my previous withdrawal and go back to 8/3 8/5

[close]

[NIHILIST]

Spoiler

He really doesn't need to make a second point, though that'd be good for him. By hitting him we SLOW HIM DOWN; next best thing for him to making his 2 point is fanning a few times to preserve what board he has left. Hitting 2 REALLY slows him down. So, if we know what his intention is, why fall for it ?

If we move from the 8 point are we really worried about him rolling 1-6 when he has 5 blots strewn around the board ? I'd be more concerned if he rolled 1-1.

Playing from the 8 point not only dodges his trap, it gives us wood to make rhe 2 point. Sign me up to move off the 8 point.

[close]

Bob

[diane]

Spoiler

Ok, you all got me on board with abandoning the prime...yes, 6-1 is the only roll that does anything after our move - and it does rkb no good anyway

[close]

[roadkillbooks]

Im looking forward to the sequence.. 11 me, 11 forum, 66 me.  If that happens I think Ill give up backgammon and take up roulette.

[diane]

 

[dorbel]

So, looks like we made a small error by selecting the no hit play. Gnu, better for rolling this out than Snowie, prefers hitting and you can choose almost any hitting play you like, picking up one or two checkers, as they all come out about the same. 8/3, 8/5 is an error costing about 0.03. I don't see any way of realistically comparing the two outcomes over the board, where hitting wins about 88% and not hitting wins about 86.5%!
One interesting feature is that hitting makes Blue's next play simple and often forced, whereas not hitting gives him many tough plays, as the 2-1 that he rolls next for example!

[ah_clem]

rollout

gnubg 0-ply shows that breaking the prime is about a .05 error, winning "only" 86% of games vs 88% for the hitting plays.  No wonder I was so confused. 





    1. Rollout          20/15* 8/5                   Eq.:  +0.770
       0.885 0.560 0.272 - 0.115 0.003 0.000 CL  +0.770 CF  +0.770
      [0.003 0.007 0.009 - 0.003 0.001 0.000 CL   0.005 CF   0.005]

    2. Rollout          20/15*/12*                   Eq.:  +0.762 ( -0.009)
       0.881 0.641 0.390 - 0.119 0.002 0.000 CL  +0.762 CF  +0.762
      [0.004 0.007 0.010 - 0.004 0.000 0.000 CL   0.008 CF   0.008]

    3. Rollout          20/17* 20/15*                Eq.:  +0.752 ( -0.018)
       0.876 0.653 0.400 - 0.124 0.002 0.000 CL  +0.752 CF  +0.752
      [0.003 0.007 0.010 - 0.003 0.000 0.000 CL   0.006 CF   0.006]

    4. Rollout          20/17* 8/3                   Eq.:  +0.749 ( -0.021)
       0.875 0.592 0.324 - 0.125 0.004 0.000 CL  +0.749 CF  +0.749
      [0.003 0.007 0.009 - 0.003 0.001 0.000 CL   0.006 CF   0.006]

    5. Rollout          20/17*/12*                   Eq.:  +0.746 ( -0.024)
       0.873 0.641 0.403 - 0.127 0.002 0.000 CL  +0.746 CF  +0.746
      [0.003 0.007 0.009 - 0.003 0.000 0.000 CL   0.006 CF   0.006]

    6. Rollout          8/5 8/3                      Eq.:  +0.721 ( -0.049)
       0.861 0.374 0.104 - 0.139 0.030 0.002 CL  +0.721 CF  +0.721
      [0.002 0.006 0.006 - 0.002 0.002 0.001 CL   0.004 CF   0.004]

    7. Rollout          20/15* 7/4                   Eq.:  +0.609 ( -0.161)
       0.805 0.538 0.333 - 0.195 0.056 0.003 CL  +0.609 CF  +0.609
      [0.003 0.007 0.009 - 0.003 0.003 0.001 CL   0.005 CF   0.005]
        Full cubeful rollout with var.redn.
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