Discussion:
Containing two checkers
(too old to reply)
Tim Chow
2020-05-30 20:27:17 UTC
Permalink
XGID=-BAaCBCaB---B---------edd-:1:-1:1:62:0:0:0:0:10

X:Player 1 O:Player 2
Score is X:0 O:0. Unlimited Game
+13-14-15-16-17-18------19-20-21-22-23-24-+
| | | O O O | +---+
| | | O O O | | 2 |
| | | O O O | +---+
| | | O O O |
| | | O |
| |BAR| |
| | | |
| | | |
| | | X X |
| X X | | X X X X |
| X X O | | X X X O X X |
+12-11-10--9--8--7-------6--5--4--3--2--1-+
Pip count X: 84 O: 67 X-O: 0-0
Cube: 2, O own cube
X to play 62

---
Tim Chow
b***@gmail.com
2020-05-31 15:34:06 UTC
Permalink
Post by Tim Chow
XGID=-BAaCBCaB---B---------edd-:1:-1:1:62:0:0:0:0:10
X:Player 1 O:Player 2
Score is X:0 O:0. Unlimited Game
+13-14-15-16-17-18------19-20-21-22-23-24-+
| | | O O O | +---+
| | | O O O | | 2 |
| | | O O O | +---+
| | | O O O |
| | | O |
| |BAR| |
| | | |
| | | |
| | | X X |
| X X | | X X X X |
| X X O | | X X X O X X |
+12-11-10--9--8--7-------6--5--4--3--2--1-+
Pip count X: 84 O: 67 X-O: 0-0
Cube: 2, O own cube
X to play 62
---
Tim Chow
If the opponent had a two point board (or even a three point board with no spares on the top point) I think 5/3* is clear. Three point board (with spares) is a lot murkier and I don't know which way I'd go.

Stick
Tim Chow
2020-06-02 00:41:27 UTC
Permalink
XGID=-BAaCBCaB---B---------edd-:1:-1:1:62:0:0:0:0:10

X:Player 1 O:Player 2
Score is X:0 O:0. Unlimited Game
+13-14-15-16-17-18------19-20-21-22-23-24-+
| | | O O O | +---+
| | | O O O | | 2 |
| | | O O O | +---+
| | | O O O |
| | | O |
| |BAR| |
| | | |
| | | |
| | | X X |
| X X | | X X X X |
| X X O | | X X X O X X |
+12-11-10--9--8--7-------6--5--4--3--2--1-+
Pip count X: 84 O: 67 X-O: 0-0
Cube: 2, O own cube
X to play 62

XG 3-ply thinks this is a close decision but plays 8/6 8/2.

Note that Stick chose not to raise the question of what the DMP play might be.

1. Rollout¹ 8/2 5/3* eq:+0.368
Player: 67.13% (G:18.91% B:0.53%)
Opponent: 32.87% (G:5.94% B:0.03%)
Confidence: ±0.006 (+0.362..+0.375) - [100.0%]

2. Rollout¹ 8/6 8/2 eq:+0.323 (-0.045)
Player: 68.56% (G:6.73% B:0.16%)
Opponent: 31.44% (G:0.52% B:0.00%)
Confidence: ±0.005 (+0.318..+0.327) - [0.0%]

3. Rollout¹ 12/6 4/2 eq:+0.265 (-0.103)
Player: 64.94% (G:9.01% B:0.23%)
Opponent: 35.06% (G:0.64% B:0.00%)
Confidence: ±0.005 (+0.260..+0.270) - [0.0%]

¹ 1296 Games rolled with Variance Reduction.
Dice Seed: 271828
Moves: 3-ply, cube decisions: XG Roller

eXtreme Gammon Version: 2.19.207.pre-release

---
Tim Chow
b***@gmail.com
2020-06-02 02:58:46 UTC
Permalink
Post by Tim Chow
XGID=-BAaCBCaB---B---------edd-:1:-1:1:62:0:0:0:0:10
X:Player 1 O:Player 2
Score is X:0 O:0. Unlimited Game
+13-14-15-16-17-18------19-20-21-22-23-24-+
| | | O O O | +---+
| | | O O O | | 2 |
| | | O O O | +---+
| | | O O O |
| | | O |
| |BAR| |
| | | |
| | | |
| | | X X |
| X X | | X X X X |
| X X O | | X X X O X X |
+12-11-10--9--8--7-------6--5--4--3--2--1-+
Pip count X: 84 O: 67 X-O: 0-0
Cube: 2, O own cube
X to play 62
XG 3-ply thinks this is a close decision but plays 8/6 8/2.
Note that Stick chose not to raise the question of what the DMP play might be.
1. Rollout¹ 8/2 5/3* eq:+0.368
Player: 67.13% (G:18.91% B:0.53%)
Opponent: 32.87% (G:5.94% B:0.03%)
Confidence: ±0.006 (+0.362..+0.375) - [100.0%]
2. Rollout¹ 8/6 8/2 eq:+0.323 (-0.045)
Player: 68.56% (G:6.73% B:0.16%)
Opponent: 31.44% (G:0.52% B:0.00%)
Confidence: ±0.005 (+0.318..+0.327) - [0.0%]
3. Rollout¹ 12/6 4/2 eq:+0.265 (-0.103)
Player: 64.94% (G:9.01% B:0.23%)
Opponent: 35.06% (G:0.64% B:0.00%)
Confidence: ±0.005 (+0.260..+0.270) - [0.0%]
¹ 1296 Games rolled with Variance Reduction.
Dice Seed: 271828
Moves: 3-ply, cube decisions: XG Roller
eXtreme Gammon Version: 2.19.207.pre-release
---
Tim Chow
That's because part of the saying is "when the dmp play is clear". Clear can have a couple of meanings but since it wasn't clear to me I thought I was safe it wasn't clear to anyone here. You sure do nitpick a lot a general principle I have plenty of people find useful, a few of them among the best players in the world. I _always_ ask myself what the dmp play is.

Stick
Paul Epstein
2020-06-02 07:09:17 UTC
Permalink
Post by b***@gmail.com
Post by Tim Chow
XGID=-BAaCBCaB---B---------edd-:1:-1:1:62:0:0:0:0:10
X:Player 1 O:Player 2
Score is X:0 O:0. Unlimited Game
+13-14-15-16-17-18------19-20-21-22-23-24-+
| | | O O O | +---+
| | | O O O | | 2 |
| | | O O O | +---+
| | | O O O |
| | | O |
| |BAR| |
| | | |
| | | |
| | | X X |
| X X | | X X X X |
| X X O | | X X X O X X |
+12-11-10--9--8--7-------6--5--4--3--2--1-+
Pip count X: 84 O: 67 X-O: 0-0
Cube: 2, O own cube
X to play 62
XG 3-ply thinks this is a close decision but plays 8/6 8/2.
Note that Stick chose not to raise the question of what the DMP play might be.
1. Rollout¹ 8/2 5/3* eq:+0.368
Player: 67.13% (G:18.91% B:0.53%)
Opponent: 32.87% (G:5.94% B:0.03%)
Confidence: ±0.006 (+0.362..+0.375) - [100.0%]
2. Rollout¹ 8/6 8/2 eq:+0.323 (-0.045)
Player: 68.56% (G:6.73% B:0.16%)
Opponent: 31.44% (G:0.52% B:0.00%)
Confidence: ±0.005 (+0.318..+0.327) - [0.0%]
3. Rollout¹ 12/6 4/2 eq:+0.265 (-0.103)
Player: 64.94% (G:9.01% B:0.23%)
Opponent: 35.06% (G:0.64% B:0.00%)
Confidence: ±0.005 (+0.260..+0.270) - [0.0%]
¹ 1296 Games rolled with Variance Reduction.
Dice Seed: 271828
Moves: 3-ply, cube decisions: XG Roller
eXtreme Gammon Version: 2.19.207.pre-release
---
Tim Chow
That's because part of the saying is "when the dmp play is clear". Clear can have a couple of meanings but since it wasn't clear to me I thought I was safe it wasn't clear to anyone here. You sure do nitpick a lot a general principle I have plenty of people find useful, a few of them among the best players in the world. I _always_ ask myself what the dmp play is.
I think if the DMP principle was: "For checker plays that require thought,
think first about what the DMP play is," it would be a better principle,
and perhaps Tim wouldn't nitpick so much.

Paul
Tim Chow
2020-06-04 04:20:56 UTC
Permalink
Post by Paul Epstein
I think if the DMP principle was: "For checker plays that require thought,
think first about what the DMP play is," it would be a better principle,
and perhaps Tim wouldn't nitpick so much.
Yes. In fact I've offered many reformulations over the years that I believe
capture the essence of what Stick is trying to say, but Stick stubbornly
insists on his formulations and refuses to acknowledge his own biases.

---
Tim Chow
Tim Chow
2020-06-04 04:46:24 UTC
Permalink
Post by b***@gmail.com
You sure do nitpick a lot a general principle I have plenty of people find
useful, a few of them among the best players in the world.
Obviously, I don't expect to be able to change your mind any more than I
expect to be able to change Murat's mind. But Paul Epstein has shown evidence
of an open mind, so it's for the benefit of people like him that I articulate
contradictions and biases in what you say, that might cause confusion.

---
Tim Chow
Tim Chow
2020-06-04 05:52:47 UTC
Permalink
Post by Tim Chow
Obviously, I don't expect to be able to change your mind any more than I
expect to be able to change Murat's mind. But Paul Epstein has shown evidence
of an open mind, so it's for the benefit of people like him that I articulate
contradictions and biases in what you say, that might cause confusion.
Let me elaborate a bit on this. Here's how I would imagine someone---let's
call her Twiggy---who is consistently trying to apply the "just make the DMP
play" maxim might analyze this position.

Twiggy says, "First of all, what's the DMP play? It might not be clear to
everyone, but it's clear to me---play safe, 8/6 8/2. Now, what about the
banana split? That might win more gammons at the cost of some wins. How
do I assess the tradeoff? It looks murky. So forget about trying to assess
it. Just make the DMP play. 8/6 8/2 it is." When the bot verdict comes in
and says to hit, Twiggy says, "Well, let's see...was I wrong that the DMP
play was clear? No. A DMP rollout puts 8/6 8/2 ahead by about 0.018, which
is clear by DMP standards. Looks like the gammon tradeoff was favorable
after all. Well, in some positions you just have to evaluate the win/gammon
tradeoff if you want to master them. But I did the best I could with the
knowledge I had."

Alternatively, Twiggy might say, "First off, what's the DMP play? Well, it's
not clear to me. Usually it's to play safe, but if O's board is crunched
enough, the banana split can be better at DMP. I'm guessing that playing
safe is better at DMP, but maybe not by a lot. Now what about gammons?
Hitting must win more gammons. If it's close at DMP then I'm going to go
with the gammonish play." Upon looking at the bot results, Twiggy says,
"Well, I guess I got the right answer, but I'm slightly surprised that 8/6
8/2 is as far ahead at DMP as it is. I need to study this sort of position
at DMP more."

Either of these would be a principled approach. Of course I've used a lot
of words and it takes effort to type out so many words. Who has the time?
But the point is that if you advertise an approach but don't practice what
you preach by following it in a principled way, and then point out when it
runs into difficulties (and what to do when difficulties are encountered),
then the approach loses credibility.

---
Tim Chow

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