Discussion:
Hypothetically, if Tim and Bill Robertie jointly wrote a backgammon book, here is the type of advice they might give which I might disagree with.
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Paul Epstein
2020-07-26 11:08:35 UTC
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On another thread, Tim gave the below position.
I'm not sure how active Robertie is as a backgammon author.
However, if he put Tim's position in a book, he would
say something like: "However, O, who is being blitzed,
is likely to have fewer decisions than X. It will be
very hard for X to squeeze every drop of equity out of
the position. Since X is likely to lose at least 0.04 equity
from inaccuracies, this is a practical take."

There are many pitfalls with this advice. Here's one of them:
Obviously, the readers are highly unlikely to meet that exact
position in practice. So the relevant practical question is:
How should the practical cube action be assessed in positions which
"look similar" to Tim's position?

If the readers are equity-omniscient and realise that the take-equity
is approx -1.03, then the Robertie advice is valid. However, such
omniscience doesn't exist. A willingness to take such cubes will lead
to players thinking they are taking at approx -1.03 when they are actually
taking at -1.2. In other words, a player can't use Robertie's reasoning OTB
but can only claim retrospectively to have followed it through luck.
Taking blitz cubes for money is very dangerous -- I would
err on the side of caution here. In other words, I think it's more common
for a position which seems takeable to be a massive drop than for a position
that looks like a drop to be a massive take. Unless you're world-class
(and probably even then), losing 0.065 on a bad pass in a blitz position
shouldn't worry you.

Paul



XGID=aB-Ba-C-B--AcD-b-bAd-b----:0:0:1:00:0:0:3:0:10

X:Player 1 O:Player 2
Score is X:0 O:0. Unlimited Game, Jacoby Beaver
+13-14-15-16-17-18------19-20-21-22-23-24-+
| X O O X | | O O |
| X O O | | O O |
| X | | O |
| X | | O |
| | | |
| |BAR| |
| | O | |
| | | |
| O | | X |
| O X | | X X X |
| O X X | | X O X X |
+12-11-10--9--8--7-------6--5--4--3--2--1-+
Pip count X: 123 O: 153 X-O: 0-0
Cube: 1
X on roll, cube action

Analyzed in Rollout
No double
Player Winning Chances: 69.05% (G:27.43% B:0.46%)
Opponent Winning Chances: 30.95% (G:6.01% B:0.27%)
Double/Take
Player Winning Chances: 68.97% (G:32.13% B:0.47%)
Opponent Winning Chances: 31.03% (G:7.17% B:0.36%)

Cubeful Equities:
No double: +0.772 (-0.228)
Double/Take: +1.034 (+0.034)
Double/Pass: +1.000

Best Cube action: Double / Pass
Paul Epstein
2020-07-26 11:11:19 UTC
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Post by Paul Epstein
On another thread, Tim gave the below position.
I'm not sure how active Robertie is as a backgammon author.
However, if he put Tim's position in a book, he would
say something like: "However, O, who is being blitzed,
is likely to have fewer decisions than X. It will be
very hard for X to squeeze every drop of equity out of
the position. Since X is likely to lose at least 0.04 equity
from inaccuracies, this is a practical take."
Obviously, the readers are highly unlikely to meet that exact
How should the practical cube action be assessed in positions which
"look similar" to Tim's position?
If the readers are equity-omniscient and realise that the take-equity
is approx -1.03, then the Robertie advice is valid. However, such
omniscience doesn't exist. A willingness to take such cubes will lead
to players thinking they are taking at approx -1.03 when they are actually
taking at -1.2. In other words, a player can't use Robertie's reasoning OTB
but can only claim retrospectively to have followed it through luck.
Taking blitz cubes for money is very dangerous -- I would
err on the side of caution here. In other words, I think it's more common
for a position which seems takeable to be a massive drop than for a position
that looks like a drop to be a massive take. Unless you're world-class
(and probably even then), losing 0.065 on a bad pass in a blitz position
shouldn't worry you.
Paul
XGID=aB-Ba-C-B--AcD-b-bAd-b----:0:0:1:00:0:0:3:0:10
X:Player 1 O:Player 2
Score is X:0 O:0. Unlimited Game, Jacoby Beaver
+13-14-15-16-17-18------19-20-21-22-23-24-+
| X O O X | | O O |
| X O O | | O O |
| X | | O |
| X | | O |
| | | |
| |BAR| |
| | O | |
| | | |
| O | | X |
| O X | | X X X |
| O X X | | X O X X |
+12-11-10--9--8--7-------6--5--4--3--2--1-+
Pip count X: 123 O: 153 X-O: 0-0
Cube: 1
X on roll, cube action
Analyzed in Rollout
No double
Player Winning Chances: 69.05% (G:27.43% B:0.46%)
Opponent Winning Chances: 30.95% (G:6.01% B:0.27%)
Double/Take
Player Winning Chances: 68.97% (G:32.13% B:0.47%)
Opponent Winning Chances: 31.03% (G:7.17% B:0.36%)
No double: +0.772 (-0.228)
Double/Take: +1.034 (+0.034)
Double/Pass: +1.000
Best Cube action: Double / Pass
In "... more common for a position..." I mean "blitz position".

Paul

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