Opening Rolls

Forum Archive : Opening Rolls

Opening 62: Could running be best?

From:   Gary Wong
Date:   24 September 1997
Subject:   Re: Opening Rolls Rollouts JellyFish Ver 3.0

Midas wrote:
> For those of you interested I've rolled out all the opening moves top
> contenders. Trials 1296 Standard Deviations 0.008. I'm not sure of the
> statistical relevance of the data with this S.D. but they,re here for
> your perusal.

Thanks for that article.  One thing surprises me a bit though, in the
results for 62:

> Top moves marked with *
> Dice  Move    Move    L7 EV   L6 Roll
> 62    24/18   13/11   +.010   +.006
> 62*   24/16           -.003   +.008
> 62    13/5            -.020   -.015
> 62    24/18   24/22   -.041   -.042

Why on earth is JF so eager to play 24/16 (and similar results running to
the outfield on 63 and 64)?  It even ranks it better than 24/18 13/11
(though admittedly the distinction is lost in the statistical noise).
The way I see it:

Advantages of 24/18 13/11:

 * 24/18 leaves the back men in communication (16 return shots on the
   bar point; only 4 on the 9 point).

 * Even if the blot on the 9 point is missed after 24/16, you'll be
   scrambling to safety it next roll, reducing your mobility.

 * 24/18 leaves good chances of anchoring on the opponent's bar point;
   24/16 gives up anchoring for now.

 * 24/18 13/11 gives a spare builder for the 5 point; 24/16 doesn't put a
   man anywhere useful (what's the use of being on your opponent's 9

 * 24/18 gives better outfield coverage; it protects against the opponent
   bringing builders to his 9, 10 or 11 points (24/16 only protects the
   10 and 11 points)

Advantage of 24/16:

 * Only gives your opponent 14 shots at your blot on his 9 point (2 of his
   rolls make the 9 point), instead of 26 shots on the bar point (6 make

Are the reduced shots on the runner really worth giving up all the
advantages of 24/18 13/11?  Let's see what the outcomes of the next two
rolls are:

                             24/16   24/18

Blot hit, return hit (best)     48     320
Blot missed (good)             792     360
Blot hit, no return hit (bad)  384     400
Blot pointed on (worst)         72     216
                              ----    ----
                              1296    1296

Hard to say whether the chance of hitting back with 24/18 is worth the risk
of him making his bar point on your head.  There's no doubt that 24/18
increases the complexity of the game, which must make it a better choice
against a weaker player.  I'd tend to play 24/18 anyway, and it puzzles me
that Jellyfish favours 24/16 in the rollouts.  Does it see something there
I'm missing?  What do other humans think?

Gary (GaryW on FIBS).
Did you find the information in this article useful?          

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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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