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Lucky roll behind a 5-prime

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12-04-2010 , 03:41 PM

jomony

grinder

Join Date: May 2010 Posts: 434

First off just want to say hello and that I think this forum is an amazing hidden gem. Never thought when I signed up on 2+2 for poker advice that I'd get to improve my backgammon game too!

Anyhow, this position came up recently. I thought it was kind of interesting, but I'm not very good so I might easily be wrong. Hopefully not though.

Blue trails 6-13 in a 17-point match. Blue has one on the bar and is to play a lucky 1-1.

BTW I've done rollouts but they don't explain the thought process involved, which is what I'm curious about here.

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12-04-2010 , 05:24 PM

Doubledouble1984

centurion

Join Date: Mar 2010 Posts: 141

Against a decent player I dont think it should matter because I dont see a play that doesn't give the opponent a double/drop from the roof anyway.

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12-04-2010 , 05:44 PM

TomCowley

Pooh-Bah

Join Date: Sep 2004 Posts: 5,649

Not sure what I play (obviously some combo of bar/24, 6/5*, and covering one of the blots). I haven't run through every roll for each, but gut is bar/24 6/5 (2) 4/3 comes out on top because it doesn't duplicate your 6s at all (which leaving a blot on the 3 would). 5s and 4s cover, 3s and 2s spy the 6, 6s escape, etc.

I don't see how this is a double next turn with 2 in the air, and especially not with a big match lead and a score where your gammons are dead if the cube goes to 4.

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12-04-2010 , 06:12 PM

Doubledouble1984

centurion

Join Date: Mar 2010 Posts: 141

Quote:

Originally Posted by TomCowley

oops! forgot about the match part. I agree, at this match score its obv. no double. however for money, I double from the roof here in a shot. If we whack that blot (after what I believe is the best play of bar/24 6/5 (2) 4/3) we have lost our market by a mile. Even in variations where we don't, we still have contained two checkers behind a five prime. I might be wrong, but I think this goes double/drop for money after the indicated play because of the amount of gammon wins after picking up the blot.

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12-04-2010 , 07:24 PM

higonefive

journeyman

Join Date: Sep 2010 Posts: 317

Quote:

Originally Posted by Doubledouble1984

The best play and then dance by white, would you give the cube and 1 point in a prop, playing this as a cash game? I wouldn't hesitate and say: "Sit down."

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12-04-2010 , 08:59 PM

Doubledouble1984

centurion

Join Date: Mar 2010 Posts: 141

Quote:

Originally Posted by higonefive

The best play and then dance by white, would you give the cube and 1 point in a prop, playing this as a cash game? I wouldn't hesitate and say: "Sit down."

If blue played bar/24 6/5 (2) 4/3 (the best play by a lot I think), and then white dances, blue should keep his hands in his pockets. If blue doubled me here after I danced, I would beaver this before the cube hit the board. Sometimes having two checkers behind a five prime counts for something. lots of people look at this, see two in the air and assume it must be a cube.

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12-06-2010 , 11:56 AM

ferrengi

grinder

Join Date: Jul 2009 Posts: 683

bar/24, 6/5*(2), 3/2

I think you have to play carefully here because of the 5 prime. Even if you are able to cover the blot on the 5 point, I don't think it is a huge improvement in the position since blue will have all the same problems he currently has. So, it is not worth the risk to leave the blot.

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12-07-2010 , 06:34 AM

ostholm

newbie

Join Date: Jan 2006 Posts: 41

I would play bar/24 6/5*(2) and 3/4. If White dances i would double, as pretty much every roll will be useful to us the only exception i can think of being 2-1 and double 3s, 4s and 5s.

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12-07-2010 , 08:02 PM

Doubledouble1984

centurion

Join Date: Mar 2010 Posts: 141

Quote:

Originally Posted by ostholm

I would play bar/24 6/5*(2) and 3/4. If White dances i would double, as pretty much every roll will be useful to us the only exception i can think of being 2-1 and double 3s, 4s and 5s.

yum yum. where can we play?

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12-07-2010 , 09:04 PM

#10

mute

Carpal \'Tunnel

Join Date: Apr 2005 Posts: 11,815

Quote:

Originally Posted by Doubledouble1984

yum yum. where can we play?

for money doubling after a fan would be pretty bad, I agree. At this score I don't mind sending it over.

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12-08-2010 , 12:13 AM

#11

ostholm

newbie

Join Date: Jan 2006 Posts: 41

Im don't play "match-play" but at the current score we have some catching up to do and this seems like a good spot. I agree that in a cashgame this is no double.

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12-08-2010 , 01:04 AM

#12

jomony

grinder

Join Date: May 2010 Posts: 434

Quote:

Originally Posted by ferrengi

This was basically my thinking and what I played, but GNU says it's 3rd-best. The winner is the seemingly-riskier bar/24 6/5*(2) 4/3, as several suggested, followed by the even riskier-looking bar/24 8/7 6/5*(2).

I admit I've never studied backgammon (hard to find a game where I live) but I can usually at least see why GNU might be suggesting something. Here I don't understand though. Is it because this gives us the best chance (albeit slim) to pin white and escape the two trapped, or are we trying to recirculate here?

For anyone interested, here's the rollout:

Code:

    1. Rollout          bar/24 6/5*(2) 4/3           Eq.:  -0.2237
       0.4235 0.1024 0.0020 - 0.5765 0.1986 0.0295 CL  -0.2426 CF  -0.2237
    2. Rollout          bar/24 8/7 6/5*(2)           Eq.:  -0.2764 ( -0.0527)
       0.4213 0.1029 0.0019 - 0.5787 0.2352 0.0508 CL  -0.3047 CF  -0.2764
    3. Rollout          bar/24 6/5*(2) 3/2           Eq.:  -0.3185 ( -0.0948)
       0.3980 0.0845 0.0012 - 0.6020 0.1904 0.0187 CL  -0.3136 CF  -0.3185
    4. Rollout          bar/24 6/5*/3                Eq.:  -0.3204 ( -0.0967)
       0.3996 0.0964 0.0020 - 0.6004 0.2116 0.0387 CL  -0.3096 CF  -0.3204

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12-08-2010 , 02:54 AM

#13

ostholm

newbie

Join Date: Jan 2006 Posts: 41

I think "to pin white and escape the two trapped" is spot on. By burying a checker you significantly reduce this happening.

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