On March 1, 2023 at 11:01:09 AM UTC-7, Robert Zimmerman wrote:
> XG agrees, Tim, that the blot on the ace point is a liability.
Ha ha ha! This is beyond funny. :) Did Ex-Gee tell you
that or did you read Ex-Gee's mind...?
Our new puppy with etiquette, fresh out of obedience
school, kissing up to Tim, trying to find his existence
among the RBG's pack of sick dogs... (One thing I've
never figured out is "Who is the alpha female? Tim?")
Anyways, let's get serious and get back to our topic.
> Below is a variant that kills O's outfield blot and makes
> It's an unsubtle change to the position, ....
> VARIANT
> XGID=-ABbBCC-B--------bbbbBcb--:0:0:1:54:0:0:3:0:10
> X to play 54
> 1. Rollout¹ 21/16 5/1 eq:+0.186
What is accomplished by creating a variant position to
make 21/16 5/1 the top play unless 21/16 5/1 is still a
the "bold" play in the variant position also, as it was one
in the original position..?
The question "54 safe or bold" applies differently to it!
But there are different ways of looking at variants of a
position where the "position itself" is not the variant.
Let's look at the same position at varying scores within
a cubeless 5-point match play, for example:
Score X=0, O=0:
6/1 5/1 eq:-0.0502 [49.1% 8.6% 0.1% - 50.9% 9.8% 0.3%]
21/16 5/1 eq:-0.2290 (-0.1788) [43.8% 10.6% 0.2% - 56.2% 14.6% 0.4%]
Since this is a match, let's switch from equity to mwc.
6/1 5/1 mwc: 49.634% [49.1% 8.6% 0.1% - 50.9% 9.8% 0.3%]
21/16 5/1 mwc: 48.328 (-1.305) [43.8% 10.6% 0.2% - 56.2% 14.6% 0.4%]
Bot starts out playing safe.
Score X=0, O=4:
6/1 5/1 mwc: 16.993% [49.4% 7.8% 0.1% - 50.6% 9.7% 0.3%]
21/16 5/1 mwc: 15.682 (-1.311) [43.3% 10.6% 0.2% - 56.% 14.4% 0.4%]
I don't know why "game winning chances" are different,
even if by little but the bot plays safe when way behind.
Score X=4, O=0:
6/1 5/1 mwc: 82.050% [49.0% 8.4% 0.1% - 51.0% 9.7% 0.3%]
8/4 6/1 mwc: 79.370 (-2.680) [40.3% 7.5% 0.1% - 59.7% 9.6% 0.2%]
21/16 5/1 mwc: 79.369 (-2.681) [44.0% 11.9% 0.4% - 56.6% 14.9% 0.6%]
Wow! What an accuracy! 8/4 6/1 replaces 21/16 5/1 as
the second choice by 0.0001 :) But what matters is that
the bot plays safe when way ahead also.
Score X=4, O=4:
6/1 5/1 mwc: 49.101% [49.1% 8.5% 0.1% - 50.9% 9.9% 0.3%]
21/16 5/1 mwc: 43.694 (-5.407) [43.7% 12.0% 0.5% - 56.3% 15.0% 0.4%]
No reason to play other than the best move. Well enough.
Score X=3, O=0:
6/1 5/1 mwc: 74.453% [49.0% 8.7% 0.1% - 51.0% 9.9% 0.3%]
21/16 5/1 mwc: 72.839 (-1.613) [43.7% 11.9% 0.5% - 56.3% 14.9% 0.4%]
The bot is quite ahead and a gammon can win the match
but it still plays safe.
Maybe this is why Philippe Michel had said, in this thread:
https://groups.google.com/g/rec.games.backgammon/c/9ICaJyXz1B0/m/w9q7cVUVEQAJ
"As far as play decisions go, this is irrelevant.
"Whatever the set score, your goal is to win
"the match you are playing.
Perhaps gamblegammon bots are just not good at playing
cubeless classic backgammon...
But can they adjust their checker play to the score and the
cube value in cubeful gamblegammon matches?
We'll take a look at that in my next post...
MK