Opening Rolls

Forum Archive : Opening Rolls

Opening 43: Which split is better?

From:   Peter Backgren
Date:   4 August 2000
Subject:   Opening 4-3 and alike
Google:   MPG.13f4a78bece23f899896b6@news

Lately I have noticed that I've developed a preference for playing the
opening 4-3 like 24-21/13-9. Could anyone provide me with the opening

The main reason I've started to dislike splitting to my opponents 5 is
that any piece I have there is such a prime target. Having split in front
of his 5 discourages him from slotting it, prevents him from hitting me
AND slotting/covering it, still presents me with a decent anchor
possibility and finally lets me play some of my awkward low rolls on my
side of the board creating a decent home/prime.


Robert-Jan Veldhuizen  writes:

I think 24/21 13/9 and 24/20 13/10 are very close. Peter's arguments for
splitting to the four are right, but with splitting to the five you have
a better chance of making this anchor, and the fivepoint anchor is
definitely worth more than the fourpoint anchor. Also, a builder on 10
is perhaps worth just a tiny bit more than one on 9. It seems like the
extra risk just about equals the extra gain.

13/10 13/9 is slightly worse, but still attractive if you want to gammon
your opponent.

Dean Gay  writes:

Perhaps there is something I'm not considering, but I've always felt
that a builder on the 9-point is a bit stronger than one on the
10-point, and I've assumed this is one reason why 24/21 13/9 does so
well in the rollouts.

I prefer the 9-point for several reasons:

1) It bears on more inner board points, giving me a good chance to
build a strong inner board, a prime, or to carry out a successful

2) I'd rather make the 9-point than the 10-point. A prime from the
4-point to the 9-point is more valuable and easier to build and manage
than one from the 5-point to the 10-point.

3) Many of the point-making numbers that result from having a checker
on the 10-point duplicate those that already play well from the 6- and
8-points. By placing a checker on the 9-point instead, rolls such as
41 or 52 become very good.

Of course the down side is that a blot on the 9-point is hit more
often, either from the 24-point or by return shots. I also like going
after the best anchor available on the defensive end. For these
reasons I most often play 24/20 13/10 with an opening 43, playing
24/21 13/9 occasionally for variety.

Robert-Jan Veldhuizen  writes:

In itself, a builder on 9 is worth more than one on 10 for the reasons
you gave. What I meant to write was that *bringing down* a builder to 10
might be just a tiny bit better than bringing one down to 9.

What's the difference? Well, a builder on 10 can still become a builder
on 9 later with a one; and a builder on 10 can also be used to build the
9 point, but never the other way around.

During the openings phase it might be worth keeping just this tiny bit
of extra flexibility. Personally, I like bringing down a builder with a
two to the 11 point best of all, because of this. It gives you the most
options for the follow-up. For the same reason, I think getting a
builder to 10 is a bit better than bringing one down to 9 on the opening
roll. Of course the number of hits also plays a role in this.

Gregg Cattanach  writes:

Doing a recursive rollout set, (rolling out all of the 2nd rolls, then
accumulating the value of the best responses to determine the best first
move), and using Snowie variance reduction rollouts, 3-ply, with equivalent
~150,000-200,000 games per 2nd move I have these results:

For money:  24/21 13/9    .007
            24/20 13/10   .005
            13/9 13/10    .002
            24/20 24/21  -.007

At Gammon Go, however:  13/9 13/10   .270
                        24/21 13/9   .260
                        24/10 13/10  .251
                        24/20 24/21  .224

so for money, the 3 most popular moves are really a tie, (.005 is
statistically insignificant).  However, when gammons count for you, and
not for your opponent, bringing two builders down is best, (which is
usually the case when two down is an option.)

My preference is 24/21 13/9 because the builder on the 9 point is more
useful, (making the 9 point is good if you don't roll an innerboard point
making combo, and it is less provocative than slotting the 20 point, and my
opponent is a bit less likely to slash away at his 4 point than his 5

Gregg C.

Dean Gay  writes:

For what it's worth, here are some rollout results for the opening 4-3
from other sources:

Michael Manolios shared his rollout results with the group a while
back. He used JellyFish 3.0, level 6, and rolled out 9076 games
(equivalent to > 32000 games):

Move         Equity  Wins  Gammons  Opp. Gammons  Std. Dev.
===========  ======  ====  =======  ============  =========
24/20 13/10  0.006   50.2  13.0     12.7 3        3
13/9 13/10   0.005   49.7  14.8     13.6 3        3
13/9 24/21   0.003   49.7  13.6     12.8 3        3

Achim Müller rolled out 12960 games with JellyFish, level 5, producing
the following:

Move          Equity  Wins  Gammons  Opp. Gammons  Std. Dev.
============  ======  ====  =======  ============  =========
24/20, 13/10  0,007   50,1  12,0     11,7          0,003
24/21, 13/9   0,015   50,3  12.5     11,5          0,003
13/9, 13/10   0,003   49,5  13.4     12,3          0,003

Torsten Schoop doesn't provide the data on his pages, but his
JellyFish and Snowie rollouts rank the plays in this order:

13/9, 24/21
13/9, 13/10
13/10, 24/20

Midas (Sorry, don't know his real name) rolled out 1296 games (SD=8)
using JellyFish 3.0: He also didn't provide complete stats, but he
shared the following with the group:

Move         Equity
===========  ======
13/9 24/21    -.003
13/9 13/10    -.004
24/20 13/10   +.009
24/20 24/21   +.003

("Chase" on FIBS and GamesGrid)
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Opening Rolls

At different match scores  (Louis Nardy Pillards, July 2002) 
Average advantage of winning opening roll  (Chuck Bower, Oct 1998) 
Choosing a strategy  (Daniel Murphy, June 2001) 
Early game rule of thumb  (Rich Munitz, Feb 2009) 
Factors to consider  (Kit Woolsey, July 1994) 
How computers play  (Kit Woolsey, Mar 1995)  [Recommended reading]
Magriel's Chapter 5  (Hayden Alfano+, May 2006)  [Long message]
Mloner vs Jellyfish  (Kit Woolsey, Dec 1995) 
Nactating a whole game  (Nack Ballard+, Jan 2011)  [Long message]
Nactation  (Jim Stutz+, June 2010) 
Nactation overview  (Nack Ballard, Oct 2009) 
Nactation--Why use it?  (leobueno+, Jan 2011) 
Opening 1's: Split or slot?  (Douglas Zare, Dec 2003) 
Opening 21: Rollout  (Stick, Mar 2006)  [GammOnLine forum]
Opening 21: Split or slot?  (Dick Adams+, Dec 2003) 
Opening 32: Rollout  (Stick, Feb 2006)  [GammOnLine forum]
Opening 43: In GOL online match  (Raccoon+, Feb 2004)  [GammOnLine forum]
Opening 43: Pros and cons  (Stick+, Jan 2006)  [GammOnLine forum]
Opening 43: Which split is better?  (Peter Backgren+, Aug 2000) 
Opening 43: Which split is better?  (Michael J. Zehr+, Mar 1996) 
Opening 51: Rollout  (Stick, Feb 2006)  [GammOnLine forum]
Opening 52: Merits of splitting  (Peter Bell, Apr 1995) 
Opening 53: Magriel's recommendation  (George Parker+, July 1997)  [Long message]
Opening 53: Split to 21?  (Alex Zamanian, Aug 2000) 
Opening 53: Why make the three point?  (Kit Woolsey+, Feb 1996) 
Opening 6's: Slot the bar point?  (Chuck Bower+, Feb 2000) 
Opening 6's: Slot the bar point?  (David Montgomery, June 1995) 
Opening 62: Could running be best?  (Gary Wong, Sept 1997) 
Opening 62: Split, run, or slot?  (Chuck Bower, May 1997) 
Opening 63: Middle Eastern split?  (Mark+, Apr 2002) 
Opening 63: Slot the four point?  (Dennis Cartwright+, Mar 2002) 
Opening 64: Make the two point?  (William Hill+, Jan 1998) 
Opening 64: Make the two point?  (Darse Billings, Feb 1995) 
Opening 64: Rollout  (Peter Grotrian, Jan 2006)  [GammOnLine forum]
Opening 64: Split to 20?  (Peter Bell, June 1995) 
Opening 64: Three choices  (Brian Sheppard, July 1997) 
Opening 65: Becker on lover's leap  (Jeffrey Spiegler+, Aug 1991) 
Opening 65: Computer rankings  (Chuck Bower, Jan 1997) 
Opening rolls ranked  (Arthur+, Apr 2005) 
Rollouts of opening 21 and replies  (Alexander Nitschke, Oct 1997) 
Rollouts of openings  (Tom Keith+, Jan 2006) 
Rollouts: Expert Backgammon  (Tom Fahland, Aug 1994) 
Rollouts: Jellyfish 3.0  (Midas+, Sept 1997) 
Rollouts: Jellyfish 3.0 level 6  (Chuck Bower, Feb 1999)  [Recommended reading]
Rollouts: Snowie 4.1  (Rene Cerutti, Apr 2004) 
Slotting the four point  (Joe Loria+, Oct 1999) 
Snowie's openers and replies  (rcerutti, Feb 1999)  [Long message]
Splitting versus building  (Dave Slayton+, Aug 2000) 
Splitting versus slotting  (Daniel Murphy, Apr 2001) 
Splitting versus slotting  (Daniel Murphy, Sept 1997) 
Trice's rankings  (Marty Storer, Feb 1992) 

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