The concession stand is open for business

[Tim Chow]

What do you buy? Hopefully not a whopper...

XGID=-BABBBB-----bB---b-cBcb-c-:1:1:1:61:0:0:3:0:10

X:Player 2 O:Player 1
Score is X:0 O:0. Money session
+13-14-15-16-17-18------19-20-21-22-23-24-+
| X O | | O X O O O |
| X O | | O X O O O |
| | | O O O |
| | | |
| | | |
| |BAR| |
| | | |
| | | |
| | | | +---+
| O | | X X X X X | | 2 |
| O | | X X X X X X | +---+
+12-11-10--9--8--7-------6--5--4--3--2--1-+
Pipcount X: 106 O: 81 X-O: 0-0
Cube : 2, X own cube
X to play 61

---
Tim Chow

[badgolferman]

13/7, 3/2

[Bradley K. Sherman]

Tim Chow <tchow...@yahoo.com> wrote:
>Score is X:0 O:0. Money session
> +13-14-15-16-17-18------19-20-21-22-23-24-+
> | X O | | O X O O O |
> | X O | | O X O O O |
> | | | O O O |
> | | | |
> | | | |
> | |BAR| |
> | | | |
> | | | |
> | | | | +---+
> | O | | X X X X X | | 2 |
> | O | | X X X X X X | +---+
> +12-11-10--9--8--7-------6--5--4--3--2--1-+

>Pipcount X: 106 O: 81 X to play 61

13/7,3/2

--bks

[Walt]

X will be 18 pips behind after this move. Running with 20/13 seems to be
the wrong idea - if we're not hit we'll have to run the next checker
asap and break contact.

So, 13/6 is what's next. OTB, I'd just play 13/6, but QF makes me think
maybe 3/2 is better. It's roughly equivalent, but allows some
flexibility with sixes, ie if we're hit and roll a 26 to enter we keep
the anchor for another roll.

But this is grasping at straws. I'll play 13/6 like any normal human.

//Walt

[Bradley K. Sherman]

Walt <walt_...@yahoo.com> wrote:
>
>But this is grasping at straws. I'll play 13/6 like any normal human.
>

Over the board, on bks-bg-autopilot, that's probably what I
would do, too. There was just something about that blot on
the two point that made me suspect Tim of juggling the
checkers, so I began looking for an alternate. So far
I have done very badly on trying to read "the invisible
hand of Tim" into his puzzles, but some days I'm more
paranoid than others.

--bks

[Stick]

If you're going to play 13/7 there is no reason to play 3/2 over 7/6.
This violates one of my rules. The rule roughly states if you have a
random ace to play with a stripped 6pt (or even semi stripped) and can
play a legit checker 7/6 there's your play.

Stick
http://www.bgonline.org/forums/

[Tim Chow]

On Oct 29, 9:39 pm, b...@panix.com (Bradley K. Sherman) wrote:
> There was just something about that blot on
> the two point that made me suspect Tim of juggling the
> checkers, so I began looking for an alternate.

While I do sometimes juggle the checkers, it's the exception rather
than the rule. In particular, the position I posted was not doctored,
except that it arose in a match rather than a money game.

---
Tim Chow

[Tim Chow]

On Oct 29, 4:32 pm, I wrote:
> XGID=-BABBBB-----bB---b-cBcb-c-:1:1:1:61:0:0:3:0:10
>
> X:Player 2   O:Player 1
> Score is X:0 O:0. Money session
>  +13-14-15-16-17-18------19-20-21-22-23-24-+
>  | X           O    |   | O  X  O  O     O |
>  | X           O    |   | O  X  O  O     O |
>  |                  |   | O     O        O |
>  |                  |   |                  |
>  |                  |   |                  |
>  |                  |BAR|                  |
>  |                  |   |                  |
>  |                  |   |                  |
>  |                  |   |                  | +---+
>  | O                |   | X  X  X  X     X | | 2 |
>  | O                |   | X  X  X  X  X  X | +---+
>  +12-11-10--9--8--7-------6--5--4--3--2--1-+
> Pipcount  X: 106  O: 81 X-O: 0-0
> Cube  : 2, X own cube
> X to play 61

This was actually a decision that eXtreme Gammon 3-ply faced. I was
playing O. eXtreme Gammon played 13/6, which is the normal play in
this sort of situation. X is playing a holding game and wants to hang
on to the 20pt and definitely doesn't want to race. However, rather
surprisingly, the rollout puts 20/13 on top. What I believe is
happening here is that O's three dead checkers on the 1pt, O's open
2pt, and O's stripped outfield points mean that X can guard the 20pt
with just a single checker, and doesn't need an anchor there! If this
is true then 20/13 has the advantage of holding on to both the 20pt
and the 13pt and giving X a spare to play with.

It's pretty surprising to me that X can try this trick when O has a
four-point board. Before overgeneralizing from this one example,
let's note that if we unkill one of O's checkers on the 1pt and put it
on the 2pt, then 13/6 floats to the top of the rollout. See variant
below.

I feel that this position should be slapped with a warning label:
"Warning: Bots are professionals. Do not try this at home."

=======
Rollout
=======

1. Rollout: 20/13 eq:-0.369
Player : 29.72% (G:3.42% B:0.08%)
Opponent: 70.28% (G:8.60% B:0.06%)
Confidence: ±0.006 (-0.375<E<-0.363)

2. Rollout: 13/6 eq:-0.414 (-0.045)
Player : 27.88% (G:2.00% B:0.04%)
Opponent: 72.12% (G:4.66% B:0.06%)
Confidence: ±0.006 (-0.420<E<-0.408)

3. Rollout: 13/7 3/2 eq:-0.426 (-0.057)
Player : 27.34% (G:1.79% B:0.04%)
Opponent: 72.66% (G:4.68% B:0.06%)
Confidence: ±0.005 (-0.431<E<-0.421)

1296 Games rolled with Variance Reduction.
Dice Seed: 2
Moves and cube decisions: 3 ply

eXtreme Gammon Version: 1.21


=======
Variant
=======

XGID=-BABBBB-----bB---b-cBcbab-:1:1:1:61:0:0:3:0:10

Score is X:0 O:0. Money session
+13-14-15-16-17-18------19-20-21-22-23-24-+

| X O | | O X O O O O |

| X O | | O X O O O |
| | | O O |
| | | |
| | | |

| |BAR| |
| | | |
| | | |
| | | | +---+
| O | | X X X X X | | 2 |
| O | | X X X X X X | +---+
+12-11-10--9--8--7-------6--5--4--3--2--1-+

Pipcount X: 106 O: 82 X-O: 0-0

Cube : 2, X own cube
X to play 61

1. Rollout: 13/6 eq:-0.419
Player : 27.51% (G:2.47% B:0.05%)
Opponent: 72.49% (G:4.99% B:0.08%)
Confidence: ±0.005 (-0.424<E<-0.414)

2. Rollout: 20/13 eq:-0.493 (-0.074)
Player : 26.56% (G:4.68% B:0.10%)
Opponent: 73.44% (G:14.33% B:0.07%)
Confidence: ±0.006 (-0.499<E<-0.487)

1296 Games rolled with Variance Reduction.
Dice Seed: 2
Moves and cube decisions: 3 ply

---
Tim Chow