Opening Rolls

 Rollouts: Jellyfish 3.0 level 6

 From: Chuck Bower Address: bower@bigbang.astro.indiana.edu Date: 20 February 1999 Subject: Re: Opening move rollouts Forum: rec.games.backgammon Google: 7al3lh\$lsp\$1@jetsam.uits.indiana.edu

```> Has anyone done extensive rollouts on opening rolls and their
> combinations?

Here are the data from my rollouts.  This is more or less what was
pubbed in FLINT AREA BACKGAMMON NEWS, Holiday (Dec) 1997 issue, with some
additions and corrections in the Jan/Feb 1998 issue.  These data are based
upon 800,000+ JFv3.0 level-6 rollouts of replies to opening rolls.  I then
combined the 'correct' replies to come up with these opening roll cubeless
equities:

21
11,23   -0.006
11,5    -0.011
31
5(2)    +0.160
41
9,23    -0.001
9,5     -0.027
51
8,23    +0.005
8,5     -0.012
61
7(2)    +0.102
32
21,11   +0.003
10,11   -0.004
42
4(2)    +0.118
52
8,22    +0.008
8,11    -0.002
62
18,11   +0.013
16      -0.011
43
9,10    +0.009
9,21    +0.007
20,10   +0.006
20,21   -0.006
53
3(2)    +0.062
63
18,10   +0.004
15      -0.003
54
8,20    +0.022
8,9     +0.012
64
2(2)    +0.010
14      +0.007
18,9    +0.004
65
13      +0.068

Statistical uncertainty (standard deviations) are estimated at
0.0022 for a given rollout and 0.0031 for comparing two rollouts.
Thus a difference of 2 X 0.0031 = 0.006 is a two standard deviation
result, meaning that there is about a 2.3% chance that an infinite
(replace with a very large number if you don't like that word  ;)
number of trials with the same robot would reverse the order of the
two plays.   (NOTE:  2.3% is the area under the standard normal curve
above an abscissa of 2.  It is merely a coincidence that a single
standard deviaion was 0.0023--2.3% divided by 10.)

If there are someone's "favorite" candidates missing, that is
partially personal bias, but it is based on previous rollouts (I've
been doing opening rolls and replies to opening rolls for ~6 years)
using previous robots (two versions of Expert Backgammon and the
earlier two versions of Jellyfish) which indicated rather significant
inferiority.  You can, for example use the above data to estimate
other openings.  E.g.  53 played 13/8, 13/10 should be reasonably
close to 52 played 13/8, 13/11.  Slotting the 5-point with 62 is
not hugely different from playing 51 13/8, 6/5.

Finally, I guess I could have kept these data secret in the hopes
of publishing a book and making lots of money.  I long ago decided
against that, because "life is too short".  (Or maybe it's because
"there aren't enough paying customers."  ;)

Chuck
bower@bigbang.astro.indiana.edu
c_ray on FIBS
```

### 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)
Magriel's Chapter 5  (Hayden Alfano+, May 2006)
Mloner vs Jellyfish  (Kit Woolsey, Dec 1995)
Nactating a whole game  (Nack Ballard+, Jan 2011)
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)
Opening 21: Split or slot?  (Dick Adams+, Dec 2003)
Opening 32: Rollout  (Stick, Feb 2006)
Opening 43: In GOL online match  (Raccoon+, Feb 2004)
Opening 43: Pros and cons  (Stick+, Jan 2006)
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)
Opening 52: Merits of splitting  (Peter Bell, Apr 1995)
Opening 53: Magriel's recommendation  (George Parker+, July 1997)
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)
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)
Rollouts: Snowie 4.1  (Rene Cerutti, Apr 2004)
Slotting the four point  (Joe Loria+, Oct 1999)
Snowie's openers and replies  (rcerutti, Feb 1999)
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)