Re: Interesting question/experiment about value of cube ownership

[MK]

On 3/1/2024 6:02 PM, Ian Shaw wrote:

> "Is making the bot auto-play the
> same as doing rollouts?"
>
> It sounds like you are asking what a rollout is?

I wasn't.

> https://www.gnu.org/software/gnubg/manual/html_node/Introduction-to-rollouts.html

I had read it many a times before.

> https://www.bkgm.com/openings/rollouts.html

This is funny. You are referring me back to the same
link that I had given in my reply to you on February
10, here in this very same thread... :) What will it
take for you guys to give some credit/benefit of the
doubt to others than just yourselves?

> Your auto-play script sounds very similar but
> I don't know exactly what it does.

Fair enough. My explaining in my previous post about
what it does in this specific experiment was probably
too brief and not very clear.

> The main difference would be that you can make your
> scripts double using your own algorithm.

Yes, in some experiment I did that but not in this one.

> Or indeed, veer from the bot's best chequer play.

I haven't done any checker experiments yet but I may.

> Minor differences might be the play settings for
> search depth and pruning.

Okay. You now made me realize that even unchecking all
of the optional settings in roll-outs, it will not be
the same as bot auto-playing. We both must have come
up with the same 0.36 ppg by coincidence. Regardless,
I believe that it's inaccurate in either case anyway.

> Try this manual sequence, and evaluate the next move.
> This gets you back to the start position. But doubles
> would be allowed, so the bot evaluation should not be
> the same as that of the opening roll.
> 64: 13/7 24/20
> 33: 24/18* 13/7
> 21: bar/24 20/18*
> 51: bar/24 18/13
> 32: 18/13

Ah, it's getting interesting. GnuBG doesn't know the
difference between the initial and recycled "starting
position". XG does but wrongly, backwards. Snowie did
but adjusted it by the wrong amount.

I first wrote about this problem with XG in response
to a related discussion in RGB, on Dec 26, 2022. See:

https://groups.google.com/g/rec.games.backgammon/c/RgcdohfwyYs/m/NtnrIaUTCAAJ

Then I checked the same problem in Gnubg and I posted
about it on the same day. See:

https://groups.google.com/g/rec.games.backgammon/c/QU1jM9aatO0/m/EBkivQ3vBQAJ

The next day after that, I checked it in Snowie and I
posted a comprehensive recap about the subject. See:

This is a very important issue regarding the ages-old
fallacy that the equity at the start of the game, i.e.
the equity of the starting position, is zero. It's not!

Anyone who really cares about the accuracy of bots'
equity calculations should make time to read the above
three threads or at least the first article in each,
because miscalculating the equity of the opening moves
ripple through the following moves, causing them all
to be wrong even if slightly but also compoundingly
depending on which bot does what how...

Incidentally, in the third thread above, you'll find a
link to one of my only two posts that ever appeared on
BKGM, this one being about the shortest possible moves
to recycle to the starting position. See:

https://www.bkgm.com/rgb/rgb.cgi?view+68

My 4-rolls solution allowed doubles and I had explained
later in RBG that it would be legal not only if initial
doubles are allowed in some variants but also when we
recycled to the starting position more than once. See:

https://groups.google.com/g/rec.games.backgammon/c/8vUhA8fpEN0/m/nXMtpFOrmFoJ

So, yes, I was the one who not only didn't assume you
could recycle only once but also tested the three bots
to see if/how they would treat the starting position if
it occurred multiple times. I guess I just like to not
stop until I get to the bottom of things...

MK