Forum Archive :
Opening Rolls
Opening 52: Merits of splitting
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Hi all,
A couple of weeks ago, Kit Woolsey posted the following, summarizing the
results of opening moves experiments using computer backgammon programs:
"5-2: The normal play for years has been 13/11, 13/8. However the newer
splitting play, 24/22, 13/8, (shunned because of the crushing 5-5 threat)
has come out a bit better. The slotting play of 13/8, 6/4 (which used to
be my choice) did not survive the rollouts -- it was clearly inferior."
I'm no expert, but the possibility of 24/22 13/8 being better than 13/11,
13/8 baffles me. 5-5 is only 1/36, and it's only really crushing when
it's followed by a dance, 1/4 of the time -- total parlay, 1/144.
Therefore, I've been thinking about the other merits of 24/22 13/8:
1.) Building rolls: The best building rolls available to the back checkers
after the split are 3-1, 4-2, and 6-4. However, these are all excellent
rolls anyway after 13/11 13/8. 3-1 makes the 5-pt, 4-2 the 4-pt, and 6-4
the bar point. Furthermore, both 3-1 and 4-2 (and 6-4, for Jellyfish
fans!) leave the player who split with a choice between good alternatives.
Why duplicate good rolls?
2.) Other rolls containing a 2: These make the 22-pt after the split,
which is nice, but not nearly as nice as the 21-pt or 20-pt. It seems
that pursuing the 22-pt would be more important after the opponent has
built a decent prime. Note that by making the 22-pt, the player reduces
the chance of later making the 21-pt or the 20-pt. Meanwhile, after 13/11
13/8, a 2 makes the 11-pt. It may not be as important as the 3-pt, but
it's nice to have, since it's 6 away from the 5-pt. Therefore, it helps
both in offense - making the 5-pt - and in defense - fighting an opponent
who's made the 5-pt.
3.) All other rolls: the only other roll that seems like it might be
better after the split is 5-4, which escapes a back checker to the 13-pt.
4.) Other potential advantages of a split: discourage opponent's outfield
development; opponent gains nothing from hitting loose on the 22-pt
Overall, the only explanation that makes sense to me is that the computer
programs place more value on a good defense than a good offense. Is
anyone familiar with how they play 3-1 or 4-2 after the split? What about
early 2-2 or 3-3: do they move the defensive anchor forward or attack?
Can anyone figure out any other reasons why the split might be good?
Thanks,
USRobots
usrobots@aol.com
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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)
- 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)
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