Opening Rolls

Forum Archive : Opening Rolls

Opening 21: Split or slot?

From:   Dick Adams
Date:   1 December 2003
Subject:   2-1 as an opening move.

The disagreement is as to which is the better 2-1 opening move.

  1) 24-23; 13-12; or
  2)  6-5;  13-12

Analysis appreciated.


Gregg Cattanach  writes:

Both plays are perfectly acceptable.  Slotting with 6-5 is clearly
better at GammonGo, and slotting is probably better for money because
of the increased gammons won.  At GammonSave, splitting is better.  In
raw equity numbers for money the two plays differ by less than .005,
so it really is a pick-em.

Gregg C.

Nathaniel Gibson  writes:

Both are acceptable, just depends on your style of play and understanding
of complex positions and backgames. In money play the two are roughly
equal. Match play is a little different.

Slotting 6-5 is more agressive, and is often seen in situations where you
are far behind in a match score (for example, down 4-0 or worse in a race
to 7) and winning a gammon is necessary to get back into the match. Bots
tend to play the split 24-23 because they don't understand backgames near
as well as humans do (although it's my understanding that Snowie 4 now
prefers the slot to the split with 2-1 due to it's increased understanding
of backgames, and still splits with 4-1 and 5-1). The slot play, while
netting more gammons, will cause you to play more backgames when the
checker gets hit.

Just my 2c.

Nathaniel Gibson

Michael Sullivan  writes:

This has been discussed on Gammonline recently, and it seems like the
strongest players have pretty much come to a consensus that slotting is
slightly better at even match scores/money for 2-1, and slightly
inferior for 4-1, 5-1.  The reason is the ideal placement of the builder
on the 11, 6 points away from the slotted 5, vs. on the 9 which is such
a powerful builder that there is a lot of duplication, or the 8, which
leaves you only a bit better than 50/50 to cover if not hit.

Slotting is a gammon-hunting play on 4-1 or 5-1, best only when behind,
or gammons are more valuable than usual.  Slotting at 2-1 stands quite
well on it's own, except at scores where *losing* the gammon is more
problematic than usual.

Even at 3a-3a, which is slightly gammon-sensitive, slotting rolls out
slightly better. That said, it's clearly close enough to be a matter of

Douglas Zare  writes:

> This has been discussed on Gammonline recently, and it seems like the
> strongest players have pretty much come to a consensus that slotting is
> slightly better at even match scores/money for 2-1, and slightly
> inferior for 4-1, 5-1.

I don't think there is a consensus. One of the recent threads there
asked about 3-away 3-away, and according to long rollouts
slotting is more right with 2-1 at 3-away 3-away than for money,
perhaps by enough to call splitting an error at 3-away 3-away.
For money, though, I think people would be surprised if one of
the alternatives were clearly better than the other.

Douglas Zare
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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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