If the cube decisions are close, then playing at a higher cube value is correct in match play. This reduced the number of games in the match, which increases the worse player’s probability
of winning it.
From: public@booksongaming.com <public@booksongaming.com>
Sent: 23 August 2022 19:54
To: 'Øystein Schønning-Johansen' <oysteijo@gmail.com>; 'Joseph Heled' <jheled@gmail.com>
Cc: Ian Shaw <Ian.Shaw@riverauto.co.uk>; 'Ezequiel Galarce' <egalarce@gmail.com>; 'bug-gnubg' <bug-gnubg@gnu.org>
Subject: RE: GNU Backgammon
Yes!
Øystein’s logic reminds me of an anecdote from years ago. A friend took a double in a non-skill position that was a clear drop. The dice bailed him out, but he redoubled way too early. He explained, “you’re the better
player so I have to do things with the cube.” I explained that the reason I’m a better player is I don’t make silly cube errors.
Best,
David
PS – he won the match, so what do I know?
Yes!
I am also very skeptical of the effect of skewed match equity tables. Why should this work?
If the best player is better he has a higher probability of winning, so his/her doubling point is appearing earlier.
However in a position type where skill is not really dominant, say no contact position, the doubling from the strongest player should rather be delayed to avoid the underdog being lucky.
I strongly believe that cube handling in matches of uneven players should rather consider the skill needed to play the specific position on the board. Just making a skewed MET is in my opinion
not the solution.
As a serious besserwisser, I am (in this case) not willing to make any effort to do any type of experiments to prove me right. (I'm just using the same logic as flat-earthers and ani-vaxxers
etc.) :-)
A personal note, if I may.
Back in the day I dabbled with rating adjusted equity tables, i.e. having the stronger player use an adjusted equity table based on the rating difference.
I was never able to make it work. If anything, it ended up with the higher rated "player" doing worse. It's possible I implemented it wrong, but I would like to see some evidence first ...
Also, using different equity tables rarely makes a difference in actual play. Again I struggled to prove that one equity table is much better in practice than others.
With todays computing power it should be much easier to set up experiments. Anyone up to the task?
(Ian might remember how I distributed the rollouts for the net training. I could not have done it without you or the others!!!)
Thanks David.
That T-12 is very interesting. I see that the subsequent tables are based on an increasing cubeless win % by 1% per 50 rating points.
The Elo formula gives a higher win rate for a given rating (in a 1-point match) than the equivalent Jacobs Table.
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Table #
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Page
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Rating point difference
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Jacobs Table cpw
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Elo cpw
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T-13
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32
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0 (even)
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50.0
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50.0
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T-15
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34
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100
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52.0
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52.9
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T-17
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36
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200
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54.0
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55.7
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T-19
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38
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300
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56.0
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58.6
|
I’ll try to construct the xml files for the tables over the next few days.
-- Ian
Ian et al,
I also included T-12 which gives the parameters for subsequent tables. Let me know if you want more.
I’m also not sure how happy the list-serv is with 5MB of attachments. I can find other ways to send them if need be.
Best,
David
Hi David,
From
https://bkgm.com/articles/Sengoku/GraphicalMatchEquity/FishEffects/index.html I understand that these are the tables used for compiling the METs.
Since we have a jac50, I assume that one would be T-14.
If you could send a picture of T-17 and T-19, that would be great.
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Table #
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Page
|
Rating point difference
|
|
T-13
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32
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0 (even)
|
|
T-15
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34
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100
|
|
T-17
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36
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200
|
|
T-19
|
38
|
300
|
Thanks,
Ian Shaw
I have a copy of the book. There are more than 60 tables in it, but if anyone knows which one(s) you’re looking for, I’m happy to send along photos.
Best,
David Levy
There was a table in the book. Tom Keith refers to it in one of his articles on
bkgm.com.
If I can resurrect an old hard drive, I'll have a look.
It ought to be possible to generate fish tables from first principles, assuming a win rate and gammon rate per player.
I think Jacobs used 24% gammon rate, which is higher than most.
Hmmm....
If my archive remembers correctly there never was a jac200 table. I don't have a copy of "Can a Fish Taste Twice as Good?", is it even a table in that book? I find no file called jac200.xml in the CVS attic either. So if there was a file
called jac200,xml it must have been a local contribution that never was checked in.
The guy who contributed this was named Craig Campbell. (Must be 20 years ago or so) Is it possible to get hold of him?
I don't know, I'm asking the creator of the equity table, maybe he has it
H Ezequiel,
Now that you mention it, I think you’re right. I wonder why it’s been omitted from the installation.
Does anyone here have a copy of the jac200 MET?
-- Ian
From: Ezequiel Galarce <egalarce@gmail.com>
Sent: 22 August 2022 15:01
To: Ian Shaw <Ian.Shaw@riverauto.co.uk>
Subject: Re: GNU Backgammon
Hello, I have contacted the creator of "jac050" and "jac100" and he told me that he thinks he remembers that he had made a "jac200", I don't have any data.
Hi Ezequiel,
I don’t think the jac200 table is available on line.
If you have the raw data, it’s easy to make a MET that gnubg can use. I could create one if you can find the data
Regards,
Ian
From: Ezequiel Galarce <egalarce@gmail.com>
Sent: 19 August 2022 22:19
To: Ian Shaw <Ian.Shaw@riverauto.co.uk>
Subject: Re: GNU Backgammon
Hello good evening, can you get the equity table "jac200.xml"?
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