Le lundi 2 novembre 2020 à 18:00:12 UTC+1, bug-gnubg-request@gnu.org <bug-gnubg-request@gnu.org> a écrit :
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Today's Topics:
1. Re: Why such discrepancy for the ranked (obviously wrong) 1st
choice between 4 ply and simulation ? (Timothy Y. Chow)
2. Re: Why such discrepancy for the ranked (obviously wrong) 1st
choice between 4 ply and simulation ? (Joseph Heled)
3. Re: Why such discrepancy for the ranked (obviously wrong) 1st
choice between 4 ply and simulation ? (pierre zakia)
----------------------------------------------------------------------
Message: 1
Date: Sun, 1 Nov 2020 15:14:08 -0500 (EST)
Subject: Re: Why such discrepancy for the ranked (obviously wrong) 1st
choice between 4 ply and simulation ?
Content-Type: text/plain; charset="iso-8859-15"; Format="flowed"
Pierre Zakia wrote:
> In the position here below, I am curious to understand what in Gnubg
> engine yields such discrepancy between 4 ply and roll out.
>
>
> GNU Backgammon ID de position: G27HAAiY2+ABAw
> ID de match : MAHyAAAAAAAE
Thanks for posting this position---it's very interesting!
First let me mention that eXtreme Gammon (XG) finds this position tricky
as well. XG 3-ply plays 13/9(2) 13/5. (XG and GNU use slightly
definitions of "ply" I think, but that's not important here.) So I don't
think that 13/9(2) 13/5 is "obviously wrong." Two things to note:
1. 13/9(2) 13/5 wins more gammons than 20/16(2) 13/9(2), so it's probably
the better play at certain match scores.
2. Suppose you change the position slightly---instead of having the cube
centered, have X own the cube on 2. I think that if you roll it out then
you'll see that 20/16(2) 13/9(2) comes out ahead by a much smaller margin.
So part of the reason that 20/16(2) 13/9(2) comes out so far ahead in your
original position is the somewhat subtle fact that O is hoping to double
next turn---but if O gets hit then she won't be able to double. So with
the cube in the middle, O is much more cautious about leaving shots.
Anyway, I don't think that this is a fault of the software. It's just
that the position is more subtle than you may have thought at first
glance.
Tim
------------------------------
Message: 2
Date: Mon, 2 Nov 2020 09:58:42 +1300
Subject: Re: Why such discrepancy for the ranked (obviously wrong) 1st
choice between 4 ply and simulation ?
Message-ID:
Content-Type: text/plain; charset="utf-8"
You can probably write a 5kg book about positions where a bot plays
different moves at 0-ply and 1-ply. No bot is good at all types of
positions.And remember, to get the higher plies the bot need to "play" the
position to this depth. With a tricky position many moves might be
inaccurate, so the higher ply is not always correct as well.
Same for rollouts.
-Joseph
> Hi everybody,
>
>
> In the position here below, I am curious to understand what in Gnubg
> engine yields such discrepancy between 4 ply and roll out.
>
>
> GNU Backgammon ID de position: G27HAAiY2+ABAw
>
> ID de match : MAHyAAAAAAAE
>
> +12-11-10--9--8--7-------6--5--4--3--2--1-+ O: gnubg
>
> | O O | | O O X | 0 point
>
> | O O | | O O | Dés jetés 44
>
> | | | O |
>
> | | | |
>
> | | | |
>
> ^| |BAR| | Match en 7 points (Videau
> : 1)
>
> | | | |
>
> | O | | |
>
> | O X | | X |
>
> | O X X X | | X O X X |
>
> | O X X X | | X O X X | 0 point
>
> +13-14-15-16-17-18------19-20-21-22-23-24-+ X: pierrez
>
> Pip counts : O 148, X 106
>
>
> *4 ply results *:
>
> *13/5 13/9(2) *+0,579
>
> 0,684 0,135 0,005 - 0,316 0,098 0,002
>
> *20/16(2) 13/9(2) *+0,570 (* -0,008*)
>
> 0,675 0,083 0,003 - 0,325 0,082 0,001
>
> *13/5(2) *+0,436 ( -0,143)
>
> 0,611 0,122 0,003 - 0,389 0,065 0,001</td>
>
>
> *Roll out :*
> 1. Roll out *20/16(2) 13/9(2)* Eq.: +0,783
>
> 0,709 0,078 0,003 - 0,291 0,089 0,000 CL +0,415 CF +0,783
>
> [0,011 0,006 0,000 - 0,011 0,012 0,012 CL 0,026 CF 0,053]
> 2. Roll out *13/5 13/9(2) * Eq.: +0,576 (* -0,207*)
>
> 0,675 0,138 0,004 - 0,325 0,101 0,002 CL +0,389 CF +0,576
>
> [0,002 0,003 0,000 - 0,002 0,002 0,000 CL 0,004 CF 0,007]
> 3. Roll out *13/5(2) * Eq.: +0,549 ( -0,233)
>
> 0,634 0,105 0,003 - 0,366 0,044 0,056 CL +0,338 CF +0,549
>
> [0,008 0,009 0,001 - 0,008 0,007 0,055 CL 0,020 CF 0,049]
>
>
> I am more interested in the relative equity (bold font) between the first
> 2 moves than in the respective absolute equity of the same moves.
>
>
> Thanks in advance to shed some light on this.
>
>
> Pierre
>
>
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Message: 3
Date: Mon, 2 Nov 2020 14:04:09 +0000 (UTC)
Subject: Re: Why such discrepancy for the ranked (obviously wrong) 1st
choice between 4 ply and simulation ?
Content-Type: text/plain; charset="utf-8"
I am aware of what you wrote, but the position doesn't look so tricky to get fooled at 4 ply (compare to roll home a massive backgame for instance), hence my question.
Pierre
-------------------------------
Le dimanche 1 novembre 2020 à 21:58:55 UTC+1, Joseph Heled <
jheled@gmail.com> a écrit :
You can probably write a 5kg book about positions where a bot plays different moves at 0-ply and 1-ply. No bot is good at all types of positions.And remember, to get the higher plies the bot need to "play" the position to this depth. With a tricky position many moves might be inaccurate, so the higher ply is not always correct as well.Same for rollouts.
-Joseph
Hi everybody,
In the position here below, I am curious to understand what in Gnubg engine yields such discrepancy between 4 ply and roll out.
GNU Backgammon ID de position: G27HAAiY2+ABAw
ID de match : MAHyAAAAAAAE
+12-11-10--9--8--7-------6--5--4--3--2--1-+ O: gnubg
| O O | | O O X | 0 point
| O O | | O O | Dés jetés 44
| | | O |
| | | |
| | | |
^| |BAR| | Match en 7 points (Videau : 1)
| | | |
| O | | |
| O X | | X |
| O X X X | | X O X X |
| O X X X | | X O X X | 0 point
+13-14-15-16-17-18------19-20-21-22-23-24-+ X: pierrez
Pip counts : O 148, X 106
4 ply results :
13/5 13/9(2) +0,579
0,684 0,135 0,005 - 0,316 0,098 0,002
20/16(2) 13/9(2) +0,570 ( -0,008)
0,675 0,083 0,003 - 0,325 0,082 0,001
13/5(2) +0,436 ( -0,143)
0,611 0,122 0,003 - 0,389 0,065 0,001</td>
Roll out :1. Roll out 20/16(2) 13/9(2) Eq.: +0,783
0,709 0,078 0,003 - 0,291 0,089 0,000 CL +0,415 CF +0,783
[0,011 0,006 0,000 - 0,011 0,012 0,012 CL 0,026 CF 0,053]
2. Roll out 13/5 13/9(2) Eq.: +0,576 ( -0,207)
0,675 0,138 0,004 - 0,325 0,101 0,002 CL +0,389 CF +0,576
[0,002 0,003 0,000 - 0,002 0,002 0,000 CL 0,004 CF 0,007]
3. Roll out 13/5(2) Eq.: +0,549 ( -0,233)
0,634 0,105 0,003 - 0,366 0,044 0,056 CL +0,338 CF +0,549
[0,008 0,009 0,001 - 0,008 0,007 0,055 CL 0,020 CF 0,049]
I am more interested in the relative equity (bold font) between the first 2 moves than in the respective absolute equity of the same moves.
Thanks in advance to shed some light on this.
Pierre
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