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Lamford: 100 Backgammon Puzzles--Snowie analysis
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Here is a list of problems in "100 Backgammon Puzzles" where Snowie
rollouts produce results that are at variance with Lamford's suggested
plays. Many of the differences are minor, with a second candidate play
performing about the same as the preferred play. Some differences are
significant (e.g., #41). Many are minor. In at least one case (#100),
Snowie's rollout results are not dependable. I have not included problems
such as #55 where Snowie's 3-ply evaluation disagrees with Lamford but
where rollouts favor his choice over Snowie's.
Checker play problems:
#17
7/3 5/4 and Lamford's 5/1 4/3 come out tied at depth 7.
#24
8/4* and Lamford's 7/4*/3 come out tied at depth 7. 8/4* wins more games
but gives up more gammons.
#41
23/13 clearly prevails over 23/17 5/1 in full rollouts. The latter rates as
a blunder in fact.
#46
Bar/23 5/4 and Bar/23 3/2 come out tied at depth 7.
Cube decisions:
#64
Lamford says no redouble/take. Full rollouts split on whether this is a
redouble or not, with the cube-adjusted numbers saying no redouble/take and
the live cube numbers saying double/take. It's extremely close in either
case. White is 67.1% (16.2%/5.3%) cubeless, putting this on the margin.
#67
In this race position, White leads 100-112, making it double/take. Full
rollouts concur. Lamford says "If the lead was just one pip more, then
Black should pass; two pips fewer and White should wait before doubling."
Here, the rollouts disagree, giving White a legitimate double at 102-112
and 103-112. 104-112 is not quite a double. Snowie agrees, though, that
it's a pass at 99-112.
#76
Lamford says no double/take. Full rollouts make this a very narrow double
and an easy take.
#77
Lamford says no double. Full rollouts put this right at the threshold, with
White at about 66%.
#78
Lamford says "This is a correct, but only marginal double and easy take".
Full rollouts have this as a clear double and take. Not to double would
be a blunder.
#79
Lamford says it is premature to redouble. Snowie figures you lose your
market on 1-1, 2-1 or 4-1, or a 3-1 or 6-1 followed by a fan, or a 4-2 then
a 1 picking up the second blot. Ergo, double/take even though you're only
58% to in. Full rollouts concur.
#86
Lamford says play on for a gammon. Full rollouts say cash now.
#92
Lamford says no double/take. Full rollouts split, with cube-adjusted
numbers saying double/take and the live cube numbers saying no double/take.
Another borderline case, evidently.
#97
Lamford says play on for a gammon. Full rollouts (not score-based) split,
with the cube-adjusted numbers saying cash, and the live cube numbers
saying play on.
#98
Lamford says redouble/take. Full rollouts (both score-based and non
score-based) say that redoubling is a moderate error. White is about 27% to
win here.
#99
Lamford says redouble/take. Snowie 3-play says redouble/pass, and this is
confirmed by rullouts with the bearoff database turned off. White is 66.9%
to win, and Black will not have a recube opportunity, so his take point is
34.0% according to Snowie. Perhaps with a different MET this would be a
take.
#100
In this trick position (all 30 checkers in White's home board), Lamford
says no double/take. Snowie full rollouts say White is 75.8% to win (with
41.0 % backgammons and 61.7% gammons), but playing out this position
manually against Snowie demonstrates that the bot doesn't understand how to
play the Black side here. I would trust Lamford over Snowie in this case.
- Michael Schell
www.cribbageforum.com
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Books
- Bagai: Classic Backgammon Revisited (Gregg Cattanach, Feb 2002)
- Bagai: Classic Backgammon Revisited #100 (Raccoon, Nov 2004)
- Bagai: Classic Backgammon Revisited--Errata (Jeremy Bagai+, Apr 2005)
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- Ball: Alpha Backgammon (James Takahashi+, May 1994)
- Ballard & Weaver: Backgammon Openings Book A (Marty Storer, Jan 2008)
- Ballard & Weaver: Backgammon Openings Book A (Mislav Radica, Nov 2007)
- Ballard & Weaver: Backgammon Openings Book A (Rob Adams+, Oct 2007)
- Ballard & Weaver: Backgammon Openings Book A (Gregg Cattanach, Oct 2007)
- Ballard & Weaver: Backgammon Openings Book A (Neil Kazaross+, Jan 2005)
- Ballard & Weaver: Backgammon Openings--Volunteers needed (Nack Ballard, June 2007)
- Barr: Barr on Backgammon (Walter Swan+, Feb 1996)
- Becker: Backgammon for Blood (Gus, Mar 2003)
- Becker: Backgammon for Blood (PTaber+, June 1999)
- Becker: Backgammon for Blood (Michael Fuhrmann, Aug 1997)
- Becker: Backgammon for Blood (Daniel Murphy, July 1997)
- Becker: Backgammon for Blood (Durf Freund+, May 1994)
- Bell: Winning with the Doubling Cube (&Atilda;˜ystein Johansen+, Apr 2006)
- Bell: Winning with the Doubling Cube (André Nicoulin, Oct 2000)
- Bell: Winning with the Doubling Cube (David Montgomery, May 1999)
- Bell: Winning with the Doubling Cube (Peter Bell, Aug 1998)
- Bell: Winning with the Doubling Cube (Jacques Torrione, Feb 1998)
- Bell: Winning with the Doubling Cube (Robert Scibelli, Dec 1997)
- Bell: Winning with the Doubling Cube (Kevin Bastian, Nov 1997)
- Bray: Backgammon for Blood (Chris Bray, Sept 2007)
- Bray: Backgammon to Win (Chris Bray, June 2007)
- Bray: Backgammon to Win, second edition (Chris Bray, Aug 2012)
- Bray: Backgammon--An Independent View (Chris Bray, May 1998)
- Bray: Backgammon--An Independent View Revisited (Chris Bray+, Jan 2005)
- Bray: Second Wind (Chris Bray, May 2007)
- Bray: What Colour is the Wind? (Chris Bray+, June 2002)
- Bray: What Colour is the Wind?--Rerelease (Chris Bray, Sept 2006)
- Brooks: Backgammon's Best Openings and Replies (Chuck Bower+, Dec 2004)
- Clay: Backgammon Winning Strategies (Michael Strato, Nov 1999)
- Clay: Backgammon Winning Strategies (Gary Wong, Jan 1998)
- Cooke & Bradshaw: Backgammon--The Cruelest Game (Chuck Bower+, Aug 1998)
- Cooke & Orléan: Championship Backgammon (Timothy Chow+, Apr 2011)
- Cooke & Orléan: Championship Backgammon (Marty Storer, Sept 2004)
- Cooke: Paradoxes and Probabilities (Neil Kazaross+, Sept 2004)
- Cooke: Paradoxes and Probabilities (Peter van Arkel+, Sept 2002)
- Cooke: Paradoxes and Probabilities (Donald Kahn, Dec 1998)
- Cooke: Paradoxes and Probabilities (Stephen Turner, Apr 1996)
- Corbett: Backgammon Problems (Stick+, Jan 2008)
- Deyong: The Playboy Book of Backgammon (Shuman Lloyd Lee, Aug 1991)
- Dwek: Backgammon for Profit (Bob Stringer, Sept 2002)
- Euler: Everyday Errors in Checker Play (BaronGossettEulerPhD+, June 2012)
- Garal: Fair Backgammon Tournament Rules (Jakob Garal, June 2007)
- Heinrich & Woolsey: New Ideas in Backgammon (Douglas Zare, Mar 2003)
- Heinrich & Woolsey: New Ideas in Backgammon (Craig E. Groeschel+, Sept 1998)
- Heinrich & Woolsey: New Ideas in Backgammon (David Montgomery, May 1997)
- Heyken & Fischer: The Backgammon Handbook (Martin Fischer, Sept 1998)
- Heyken & Fischer: The Backgammon Handbook (Marina Smith, Feb 1998)
- Hickey & Storer: What's Your Game Plan? (Timothy Chow, May 2011)
- Jacoby & Crawford: The Backgammon Book (Patrick Wilken, Aug 1991)
- Kansil: The Backgammon Quiz Book (Daniel Murphy, July 1997)
- Kansil: The Backgammon Quiz Book--Five problems (Chuck Bower, Oct 1997)
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- Kennedy & Papazian: Backgammon Master Games (Ben Fairbank+, Apr 1999)
- Kershaw: Backgammon Funfair (Tom Keith+, July 2012)
- Kershaw: Backgammon Funfair (Peter Bennet, May 2012)
- Lamford: 100 Backgammon Puzzles (Harold Simon+, Oct 2001)
- Lamford: 100 Backgammon Puzzles (Mark Driver, July 2001)
- Lamford: 100 Backgammon Puzzles--Snowie analysis (Michael Schell, Oct 2001)
- Lamford: Improve Your Backgammon (Alef Rosenbaum, May 2003)
- Leet: Winning Backgammon (Ryan Long, Apr 2002)
- Leet: Winning Backgammon (MW Book Review, July 1999)
- Lortz: Double ... now: An Authentic Cube Remedy (Chuck Bower+, Jan 2004)
- Mabardi & Luce: Vanity Fair's Backgammon to Win (Paul Tanenbaum, Feb 1998)
- Magriel: Backgammon (Baldo+, Mar 2004)
- Magriel: Backgammon (Neil Kazaross, July 2003)
- Magriel: Backgammon (Chuck Bower, Nov 1999)
- Magriel: Backgammon (Dean Gay, Sept 1999)
- Magriel: Backgammon (David Montgomery+, Aug 1997)
- Magriel: Backgammon--2004 Edition (Tom Keith+, Dec 2004)
- Magriel: Backgammon--GnuBG evaluations (Randy, July 2008)
- Martyn: Phillip Martyn on Backgammon (Steve Brorens+, Nov 1996)
- Munchkin: Gambling Wizards (Chuck Bower, Aug 2003)
- Obolensky & James: Backgammon the Action Game (Edward D. Collins+, Oct 1999)
- Reese & Brinig: Backgammon: The Modern Game (Al Mirpuri+, Sept 2011)
- Robertie: 501 Essential Backgammon Problems (Paul Epstein, July 2005)
- Robertie: 501 Essential Backgammon Problems (Albert Silver, Nov 2002)
- Robertie: 501 Essential Backgammon Problems (Tore Fredriksen, July 2002)
- Robertie: 501 Essential Backgammon Problems (Erik M Sørensen, May 2000)
- Robertie: 501 Essential Backgammon Problems (Daniel Hollis, May 2000)
- Robertie: 501 Essential Backgammon Problems #75 (Hardy Hübener+, Nov 2005)
- Robertie: Advanced Backgammon (Doni+, Jan 2005)
- Robertie: Advanced Backgammon (Scott Steiner+, Sept 2002)
- Robertie: Advanced Backgammon (James Eibisch, Jan 1998)
- Robertie: Advanced Backgammon (Allen R. Adams, Nov 1995)
- Robertie: Advanced Backgammon #165 (Peter Grotrian+, Mar 2005)
- Robertie: Advanced Backgammon--Errata (Matt Senecal+, Nov 2004)
- Robertie: Advanced Backgammon--JF rollouts (Øystein Johansen, June 2001)
- Robertie: Advanced Backgammon--JF rollouts (Alexander Nitschke, Feb 1997)
- Robertie: Advanced Backgammon--JF rollouts (Peter Fankhauser, Jan 1996)
- Robertie: Backgammon for Winners (Carl Tait, Aug 1998)
- Robertie: Backgammon for Winners (Gerry Tesauro, Oct 1993)
- Robertie: Modern Backgammon (Mattias+, Apr 2003)
- Robertie: Modern Backgammon (Gregg Cattanach, Oct 2002)
- Robertie: Modern Backgammon (Frank Mazza+, May 2002)
- Robertie: Reno 1986 (AH+, Aug 2007)
- Shiina: Cube Action 1000 (Mochy, Feb 2013)
- Steed: Backgammon: The Meanest Game (Albert Steg, Aug 1998)
- Stern: Backgammon: The Quick Course to Winning Play (Mark Driver, May 2001)
- Storer: Backgammon Praxis (Chase+, Apr 2007)
- Storer: Backgammon Praxis (Marty Storer+, May 2004)
- Thorne's Backgammon Tactics (Reprint) (Sam Sloan, July 2012)
- Tremaine: Amazing Book of Backgammon (Jim Wallace, Feb 1998)
- Trice: Backgammon Boot Camp--2nd edition (Jeremy Bagai+, June 2007)
- Tzannes brothers: Backgammon Games and Strategies (Mark Driver, Apr 2001)
- Tzannes brothers: Backgammon Games and Strategies (Albert Steg, May 1994)
- Tzannes brothers: How Good Are You at Backgammon? (Mark Driver, July 2001)
- Wiggins: Boards, Blots, and Double Shots (Ned Cross+, Mar 2004)
- Williams: Backgammon Live in London (Sean Williams+, June 2008)
- Woolsey & Beadles: 52 Great Backgammon Tips (Paul Epstein+, Dec 2007)
- Woolsey & Beadles: 52 Great Backgammon Tips (Mislav Radica+, Oct 2007)
- Woolsey & Jones: Understanding Backgammon (Jon Nall+, Feb 2004)
- Woolsey: How to Play Tournament Backgammon (John Bazigos, Oct 1994)
- Woolsey: The Backgammon Encyclopedia Vol 1 (Dean Gay+, Feb 2004)
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