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RE: [Bug-gnubg] Fwd: An important link and a question about using EPC va
RE: [Bug-gnubg] Fwd: An important link and a question about using EPC values in deciding cube actions
Fri, 4 Feb 2011 14:07:39 -0000
Gnubg doubling decisions are based on Rick Janowksi's
theory, which I don't think any human would want to replicate over the
Gnubg does not use the epc or any other adjusted
pip-count method, which are intended for humans. These are included purely for
humans to use as a study aid.
The best information I have on epc is in Walter Trice's
Backgammon Boot Camp, which is derived from his articles at Gammon Village.
There are further articles at GV by Trice and by Douglas Zare that
expand on the information found in Boot Camp. Thanks for the link to Joachim's paper, which I'll
enjoy reading. I haven't read it yet, so I can't tell whether it adds new
information, or summarizes what is already known - a valuable thing in itself.
Trice explains that there is no general formula
applicable to all situations. This is because the epc only tells you the average
rolls to bear off, but not the amount of variance. If one player
is stacked, a 65 is about as good as a 21, so there is less variance
involved. This effect tends to help the leader, because the trailer is relying
on the variance swings to catch up in the race. This means that for equal epc
races, the trailer is better off in "pips vs. pips" races". So.
although there is no universal formula, there are different rules that can be
applied depending on whether the nature of the race is "pips vs. pips", "pips
vs.. rolls" or "rolls vs. rolls".
Note to developers:
It might be a nice touch if Trice's formulae were added
to the gnubg race theory tab. It could possibly replace the 8-9-12 rule, which
applies in similar situations but is less accurate.
Oops sorry I forgot to put the link in the last delivery. It's
---------- Forwarded message ----------
From: Adi Kadmon <address@hidden>
Fri, Feb 4, 2011 at 3:42 PM
Subject: An important link and a question about
using EPC values in deciding cube actions
(1) As a sequel to a correspondence some months ago, here is a link for
downloading Joachim Matussek's important article about an
approximation-formula for EPC values and their use in cube decisions in
bearoff positions. This time it's the original article, and in English - not
just some section about it in a later article by someone else and moreover in
the Danish language.
(2) I'd like to ask if there is at present a general formula for deciding
cube decisions in bearoff positions after the correct EPC values are
already given. I mean, does GNU make some particular computation on
the EPC values it extracts using its data-bases? For instance, let's
say Black has a raw pip count of 57 and EPC=65.41, and White has a
raw pip count of 60 pips and EPC=70.55, and it's White's roll. Does GNU use a
certain "formula" with these figures in order to reach its evaluation of the
correct cube decision? If so, does GNU use the same formula in any position
whatsoever, or is a different variant of a formula needed for each different
type of positions?
Anyway, even if GNU does not use such formula(s), what
are the current most modern approximation formulas (given already the exact
EPC values) for humans to use?