Here I made the correct play, but it felt like a total guess.
I don't know exactly how to reason my way to avoid the
blunder but I suppose one of those ace-point type books
written by Bob Wachtel would help. Tim probably has all
of them ("all" includes the possibility that only one exists.)

I suppose my problem (the reason I had to guess rather than
work it out) is that I didn't know how to evaluate the race if
I leave the 5 point open and XG steps into it. In that case,
is my race so bad that I prefer the contact?
Axelising those positions would have helped, I guess.
It's troubling to be so clueless in a position where so much equity
is at stake.
This shows an additional unrecognised form of luck at backgammon.
Besides the luck of the good rolls (here, my roll was actually bad),
there's also the luck of making the good plays by chance.
And there's also the luck of which opponents you get matched with.
And there's a luck element on whether threads initiated on rgb get
good responses.

Paul



XGID=aECCC-----A------------fb-:1:1:1:54:0:0:3:0:10
X:Daniel O:eXtremeGammon

Score is X:0 O:0. Unlimited Game, Jacoby Beaver
+13-14-15-16-17-18------19-20-21-22-23-24-+
| | | O O |
| | | O O |
| | | O |
| | | O |
| | | 6 |
| |BAR| |
| | O | X |
| | | X |
| | | X X X X | +---+
| | | X X X X | | 2 |
| X | | X X X X | +---+
+12-11-10--9--8--7-------6--5--4--3--2--1-+
Pip count X: 42 O: 39 X-O: 0-0
Cube: 2, X own cube
X to play 54

1. 4-ply 10/5 4/Off eq:+0.151
Player: 47.66% (G:0.00% B:0.00%)
Opponent: 52.34% (G:0.00% B:0.00%)

2. 4-ply 10/1 eq:+0.007 (-0.144)
Player: 43.70% (G:0.00% B:0.00%)
Opponent: 56.30% (G:0.00% B:0.00%)


eXtreme Gammon Version: 2.10

--- SoupGate-Win32 v1.05
* Origin: fsxNet Usenet Gateway (21:1/5)

On 6/3/2022 7:46 AM, peps...@gmail.com wrote:

Here I made the correct play, but it felt like a total guess.
I don't know exactly how to reason my way to avoid the
blunder but I suppose one of those ace-point type books
written by Bob Wachtel would help. Tim probably has all
of them ("all" includes the possibility that only one exists.)

Wachtel's book would not help you in this position.

I suppose my problem (the reason I had to guess rather than
work it out) is that I didn't know how to evaluate the race if
I leave the 5 point open and XG steps into it. In that case,
is my race so bad that I prefer the contact?

It's very rare that you prefer to be hit, and this position is no
exception. What's going on here is that bearing a checker is so
valuable that you're willing to leave a shot even though you'd
rather not get hit. Because of parity considerations, bearing a
checker here will often save you a whole roll.

This shows an additional unrecognised form of luck at backgammon.
Besides the luck of the good rolls (here, my roll was actually bad),
there's also the luck of making the good plays by chance.
And there's also the luck of which opponents you get matched with.
And there's a luck element on whether threads initiated on rgb get
good responses.

I have mentioned before the excellent book "Characteristics of Games"
by Elias, Garfield, and Gutschera. I had a long debate with Elias
and Garfield about precisely the above point. They were inclined to
use the term "luck" for all forms of randomness. That would match
your usage of the word "luck." I, on the other hand, prefer to
distinguish between "systemic" randomness (from the dice) and
"agential" randomness (what you're calling "unrecognised" luck).
For me, *skill is a random variable*. So there's randomness involved
in skill as well. If forced to use the word "luck" without an
adjective, I would prefer to use "luck" to mean "systemic randomness"
and not use it to refer to agential randomness. Elias and Garfield
prefer to use skill to refer to what I would call the expected value
of the skill random variable, and lump together systemic and agential randomness into one big thing that they interchangeably call "luck"
or "randomness." It's true that from their perspective as game
designers/game critics, the distinction between the two kinds of
randomness is not so important, especially since it's not so easy to disentangle them in practice for many games. But backgammon has a
very clean way of defining systemic randomness (which we call "luck")
so I'd rather preserve that, and use "agential randomness" for your "unrecognised luck."

---
Tim Chow

--- SoupGate-Win32 v1.05
* Origin: fsxNet Usenet Gateway (21:1/5)

On Friday, June 3, 2022 at 2:01:16 PM UTC+1, Tim Chow wrote:

On 6/3/2022 7:46 AM, peps...@gmail.com wrote:

Here I made the correct play, but it felt like a total guess.
I don't know exactly how to reason my way to avoid the
blunder but I suppose one of those ace-point type books
written by Bob Wachtel would help. Tim probably has all
of them ("all" includes the possibility that only one exists.)

Wachtel's book would not help you in this position.

I suppose my problem (the reason I had to guess rather than
work it out) is that I didn't know how to evaluate the race if
I leave the 5 point open and XG steps into it. In that case,
is my race so bad that I prefer the contact?

It's very rare that you prefer to be hit, and this position is no
exception. What's going on here is that bearing a checker is so
valuable that you're willing to leave a shot even though you'd
rather not get hit. Because of parity considerations, bearing a
checker here will often save you a whole roll.

...
Thanks for your thoughts. I didn't mean to compare being hit with not
being hit.
My intended comparison is the opponent's hitting 5's vs the opponent's non-hitting 5s.
In other words, which play works better in the variants where XG rolls a 5 on the next roll.

Paul

--- SoupGate-Win32 v1.05
* Origin: fsxNet Usenet Gateway (21:1/5)

On Friday, June 3, 2022 at 2:01:16 PM UTC+1, Tim Chow wrote:

On 6/3/2022 7:46 AM, peps...@gmail.com wrote:

Here I made the correct play, but it felt like a total guess.
I don't know exactly how to reason my way to avoid the
blunder but I suppose one of those ace-point type books
written by Bob Wachtel would help. Tim probably has all
of them ("all" includes the possibility that only one exists.)

Wachtel's book would not help you in this position.

I suppose my problem (the reason I had to guess rather than
work it out) is that I didn't know how to evaluate the race if
I leave the 5 point open and XG steps into it. In that case,
is my race so bad that I prefer the contact?

It's very rare that you prefer to be hit, and this position is no
exception. What's going on here is that bearing a checker is so
valuable that you're willing to leave a shot even though you'd
rather not get hit. Because of parity considerations, bearing a
checker here will often save you a whole roll.

This shows an additional unrecognised form of luck at backgammon.
Besides the luck of the good rolls (here, my roll was actually bad), there's also the luck of making the good plays by chance.
And there's also the luck of which opponents you get matched with.
And there's a luck element on whether threads initiated on rgb get
good responses.

I have mentioned before the excellent book "Characteristics of Games"
by Elias, Garfield, and Gutschera. I had a long debate with Elias
and Garfield about precisely the above point. They were inclined to
use the term "luck" for all forms of randomness. That would match
your usage of the word "luck." I, on the other hand, prefer to
distinguish between "systemic" randomness (from the dice) and
"agential" randomness (what you're calling "unrecognised" luck).
For me, *skill is a random variable*. So there's randomness involved
in skill as well. If forced to use the word "luck" without an
adjective, I would prefer to use "luck" to mean "systemic randomness"
and not use it to refer to agential randomness. Elias and Garfield
prefer to use skill to refer to what I would call the expected value
of the skill random variable, and lump together systemic and agential randomness into one big thing that they interchangeably call "luck"
or "randomness." It's true that from their perspective as game
designers/game critics, the distinction between the two kinds of
randomness is not so important, especially since it's not so easy to disentangle them in practice for many games. But backgammon has a
very clean way of defining systemic randomness (which we call "luck")
so I'd rather preserve that, and use "agential randomness" for your "unrecognised luck."

The skill aspects of backgammon certainly make a random variable.
I can identify at least three elements so maybe it's the sum of three independent variables.
1) I hypothesize a psychological state which can't readily be controlled. Despite taking
the usual precautions of good diet and the right amount of sleep, the focus and concentration levels
of the individual can't readily be controlled and are therefore a random variable.
2) Where the player is unsure and has to guess at the right play, the guess might be wrong or right.
3) The player is better at some aspects of backgammon than others. There's a random variable
which determines whether the positions encountered cater to the player's strengths or weaknesses.
For example, take Axel. His PR is about 5.0, but he's a superhuman genius at racing, due to his Isight algo.
So, if every game is a race, he would probably even outplay Mochy.

Paul

--- SoupGate-Win32 v1.05
* Origin: fsxNet Usenet Gateway (21:1/5)

On 6/3/2022 12:19 PM, peps...@gmail.com wrote:

Thanks for your thoughts. I didn't mean to compare being hit with not
being hit.
My intended comparison is the opponent's hitting 5's vs the opponent's non-hitting 5s.
In other words, which play works better in the variants where XG rolls a 5 on the next roll.

That's what I was talking about. If you knew in advance that
XG was going to roll a 5 then you would play safe.

By the way, I don't understand how this is *not* a comparison
between being hit with not being hit. In one case you're being
hit, and in the other case you're not being hit, and we're comparing
the two cases.

---
Tim Chow

--- SoupGate-Win32 v1.05
* Origin: fsxNet Usenet Gateway (21:1/5)