Terminology

 "Gammon price"

 From: Ron Karr Address: karr@best.com Date: 26 August 1996 Subject: Re: Match Equity Tables Forum: rec.games.backgammon Google: 3222063B.5A15@best.com

```Peter Fankhauser wrote:
> Just, what exactly is the famed "gammon price"?
> I've heard this term now quite often, but neither Kit Woolsey's
> monography on Tournament Backgammon, nor Tom Keith's pages on
> cube strategy in matches (nor his glossary btw) use this term.
> Although the market-window-tables (takepts for both players)
> for different gammon rates in TK's pages might be a different
> perspective on this.
>
> If anyone knowledgeable cares to post doubling window table
> (that's the easy part) + a definition of gammon prices + a
> few hints how to use this stuff (that is how to adjust the
> doubling window according to the gammon price) I'd be very greatful
> (and I assume lots of others too:)

The gammon price represents the relative value of a gammon swing vs a
win-loss swing.  In money games, the gammon price is always 50%.  It's
computed as:

GP = (equity from winning a gammon - equity from winning a plain game)
divided by (equity from winning a plain game - equity from losing a plain
game)

or GP = (G-W)/(W-L)

For money (G-W) is one unit, (W-L) is 2 units, so GP is 50%.

This figure is used in a couple of ways:

1.  To adjust the take point to account for gammons.  If I expect to get
gammoned x%, I need to add x% times the gammon price to my basic take
point.  So for money, if I expect to be gammoned 20% of the time, I need an
additional 10% wins over the basic 25%, or 35%, to take.

2.  To calculate play decisions.  If I'm considering taking extra risks to
win a gammon, I can take the risk as long as my extra losses are no more
than 50% of my extra gammons.  Conversely, if I'm risking losing a gammon
in order to try for the win, I must make sure that my extra wins are more
than 50% of my extra gammon losses.

(As far as computing the minimum doubling point, I don't know how to use
the gammon price.  People seem to estimate a % of gammons and factor that
into the normal calculations.)

In match strategy, the gammon price can vary from 0 to 100%.  For example,
at Crawford-odd, the trailer's gammon price is approximately zero; at
Crawford-even, it's 100%.  (The leader's gammon price is zero in both
cases)

At a score of 2-away, 4-away, for example, you need to know the gammon
price for both players, with a 1-cube or a 2-cube.

Leader, 1-cube:  GP = (100 - 83)/ (83 - 60) = 74%
Leader, 2-cube: GP = (100-100)/(100-50) = 0
Trailer, 1-cube:  GP = (50-40)/(40-17) = 43%
Trailer, 2-cube: GP = (100-50)/(50-0) = 100%

(There are some extra variables too, like what happens if both players have
significant gammon chances?  For money, you can use net gammons times
gammon price to compute the offset to the take point.  But in matches,
where each side's gammons are worth different amounts, it gets complicated
and I'm not really sure what the formula is.)

Ron
```

### Terminology

Alphabet soup  (Tom Keith, Apr 2004)
"Anchor and guard" position  (Chase+, Apr 2010)
"Back game"  (Marty Storer, Jan 2004)
"Baffle box"  (garyo+, Mar 2005)
"Bagai position"  (Timothy Chow, Dec 2012)
"Banana split"  (Rich Munitz+, June 2011)
"Banana split"  (Adam Stocks+, Sept 2004)
"Beavers"  (Sander van Rijnswou, May 1999)
"Beavers"  (Shuman Lloyd Lee, Aug 1991)
"Blunder", "whopper"  (Raccoon+, July 2005)
"Bot"  (Pit Bull+, Mar 2004)
"Bronstein" clock setting  (rew+, Sept 2012)
"Calcutta auction"  (Roland Scheicher+, Dec 2001)
"Chouette"  (Roland Scheicher+, Mar 2002)
"Cube provocation play"  (Chuck Bower+, Apr 2007)
"Dance"  (William R. Tallmadge, May 1998)
"Dropper"  (Robert D. Johnson, Sept 1996)
"Duplication" and "diversification"  (Simon Woodhead, Nov 1991)
"Equity"  (Gregg Cattanach, Aug 2000)
"Equity"  (Gary Wong, Dec 1998)
"Equity"  (Chuck Bower, Oct 1996)
"Equity"  (Michael J. Zehr, Mar 1996)
"Equity", "volatility", "claim", "market"  (Erik Gravgaard, June 1995)
"Freeroll"  (montygram, Nov 2005)
"Gammon price"  (Ron Karr, Aug 1996)
"Gammon rate", "gammon price"  (David Montgomery, June 1995)
"Gammon-go" (GG) and "gammon-save" (GS)  (Mary Hickey, Feb 2004)
"Gammon-go" (GG) and "gammon-save" (GS)  (Marty Storer, Oct 2002)
"Gammon-go" (GG)   (Chuck Bower, Jan 2004)
"Golden point"  (Daniel Murphy, Dec 2004)
"Holding game"  (Alan Webb+, Dec 1998)
"In the box"  (Ken Bame+, Sept 2012)
International phrase dictionary  (David Allen Sorensen, Sept 1997)
"Joker"  (Richard Divdesman, Sept 1998)
"Kamikaze play"  (Bill Patterson+, June 2011)
"Kauder paradox"  (Carl Tait+, Nov 1995)
"Latto paradox"  (Jean-Pierre Seiman+, July 2004)
"Lose your market"  (Shuman Lloyd Lee+, Aug 1991)
"PRaT"  (Raccoon+, Jan 2007)
"Phantom double hit"  (Marty Storer, May 2010)
"Polish prime"  (Jason Lee+, Jan 2006)
"Pure play"  (Daniel Murphy, Nov 2000)
"Pure play"  (Casey Forrest+, Feb 1996)
"Raccoon"  (Steven Keats, Feb 2011)
"Root number"  (Ken Bame, June 2004)
"Russian Bridges"  (leobueno+, Mar 2013)
"Short play"  (AJ+, July 2012)
"Speed board"  (Gregg Cattanach, June 2004)
"Splot"  (mamabear, Apr 2007)
"Squeeze", "trap play"  (Philippe Michel+, Feb 1997)
"Suicide play"  (Brian Sheppard, Aug 1997)
"Swing tournament"  (Carlo Melzi+, Mar 2006)
"Table stakes"  (Carlo Melzi, Sept 2002)
"Technical play"  (Adam Stocks+, July 2002)
"Thematic"  (Beauregard+, Aug 2009)
"Thorp count"  (Stephen Turner, June 1996)
"Time," "timing," "checker," "dancing"  (Marty Storer, Apr 1992)
Turkish names for rolls  (Lars Soezueer, Mar 1997)
"Vigorish"  (Anthony R Wuersch, Feb 1995)
"Volatility"  (Michael J. Zehr, June 1998)
"Wash"  (Hardy Hübener+, Sept 2004)
"Wash"  (Brian Sheppard, July 1997)
"Weaver"  (Alan Webb+, May 2000)
"Zone" of attack  (Matt Reklaitis+, Dec 2007)