• Hit or make the 5pt?

    From Timothy Chow@21:1/5 to All on Sun Jan 2 12:25:56 2022
    XGID=-a----EaCAA-dC--ab-d---bB-:0:0:1:53:0:0:0:0:10

    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-+
    | X O O | | O O X |
    | X O | | O O X |
    | X | | O |
    | | | O |
    | | | |
    | |BAR| |
    | | | X |
    | O | | X |
    | O X | | X |
    | O X | | X |
    | O X X X O | | X O |
    +12-11-10--9--8--7-------6--5--4--3--2--1-+
    Pip count X: 160 O: 147 X-O: 0-0
    Cube: 1
    X to play 53

    ---
    Tim Chow

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Timothy Chow@21:1/5 to All on Tue Jan 4 23:50:58 2022
    XGID=-a----EaCAA-dC--ab-d---bB-:0:0:1:53:0:0:0:0:10

    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-+
    | X O O | | O O X |
    | X O | | O O X |
    | X | | O |
    | | | O |
    | | | |
    | |BAR| |
    | | | X |
    | O | | X |
    | O X | | X |
    | O X | | X |
    | O X X X O | | X O |
    +12-11-10--9--8--7-------6--5--4--3--2--1-+
    Pip count X: 160 O: 147 X-O: 0-0
    Cube: 1
    X to play 53

    Making the 5pt would be a plausible candidate if X didn't have a
    vulnerable blot on his 9pt. As matters stand, making the 5pt gives
    O free rein to consolidate her position and maybe even go on the
    offensive with a hit.

    Should X hit twice or play 24/16*? If X's back checkers were in
    danger of getting boxed in then he might play 24/16* despite the
    large number of blots and shots it leaves. But again, as matters
    stand, the seemingly awkward double hit comes out way on top of
    the rollout.

    1. Rollout¹ 10/7* 6/1* eq:-0.068
    Player: 48.95% (G:16.93% B:0.71%)
    Opponent: 51.05% (G:18.18% B:1.59%)
    Confidence: ±0.014 (-0.082..-0.054) - [100.0%]

    2. Rollout¹ 24/16* eq:-0.167 (-0.099)
    Player: 47.71% (G:13.36% B:0.76%)
    Opponent: 52.29% (G:19.78% B:1.49%)
    Confidence: ±0.014 (-0.181..-0.152) - [0.0%]

    3. Rollout¹ 10/5 8/5 eq:-0.181 (-0.114)
    Player: 46.01% (G:14.64% B:0.60%)
    Opponent: 53.99% (G:17.19% B:1.06%)
    Confidence: ±0.015 (-0.197..-0.166) - [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

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Timothy Chow@21:1/5 to All on Fri Feb 18 21:23:53 2022
    XGID=-b----E-E--AcBa---abbbb-B-:1:1:1:63:0:0:0:0:10

    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-+
    | X O O | | O O O O X |
    | X | | O O O O X |
    | | | |
    | | | |
    | | | |
    | |BAR| |
    | X | | X |
    | X | | X |
    | O X | | X | +---+
    | O X | | X O | | 2 |
    | O X X | | X O | +---+
    +12-11-10--9--8--7-------6--5--4--3--2--1-+
    Pip count X: 155 O: 141 X-O: 0-0
    Cube: 2, X own cube
    X to play 63

    ---
    Tim Chow

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Timothy Chow@21:1/5 to All on Sun Feb 20 12:10:48 2022
    XGID=-b----E-E--AcBa---abbbb-B-:1:1:1:63:0:0:0:0:10

    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-+
    | X O O | | O O O O X |
    | X | | O O O O X |
    | | | |
    | | | |
    | | | |
    | |BAR| |
    | X | | X |
    | X | | X |
    | O X | | X | +---+
    | O X | | X O | | 2 |
    | O X X | | X O | +---+
    +12-11-10--9--8--7-------6--5--4--3--2--1-+
    Pip count X: 155 O: 141 X-O: 0-0
    Cube: 2, X own cube
    X to play 63

    This is a tough call I think. Making the 5pt gives X some much-needed structure, unstacking his heavy 8pt and cleaning up an outfield blot,
    whereas breaking anchor leaves X open to a gammonish counterattack.
    But if O makes her bar point while X still has two checkers on O's
    ace point then it's almost game over for X.

    1. Rollout¹ 24/18* 11/8 eq:-0.539
    Player: 30.52% (G:7.33% B:0.42%)
    Opponent: 69.48% (G:32.24% B:1.82%)
    Confidence: ±0.010 (-0.548..-0.529) - [89.6%]

    2. Rollout¹ 24/18* 18/15 eq:-0.547 (-0.009)
    Player: 30.37% (G:7.10% B:0.41%)
    Opponent: 69.63% (G:33.12% B:1.94%)
    Confidence: ±0.010 (-0.557..-0.538) - [10.4%]

    3. Rollout¹ 11/5 8/5 eq:-0.590 (-0.052)
    Player: 25.78% (G:7.09% B:0.40%)
    Opponent: 74.22% (G:26.29% B:1.85%)
    Confidence: ±0.009 (-0.600..-0.581) - [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

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Timothy Chow@21:1/5 to All on Sun Jun 5 08:14:20 2022
    XGID=-B-Aa-D-CbaC---B---bbabbb-:1:1:1:31:0:0:0:0:10

    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-+
    | X | | O O O O O O |
    | X | | O O O O O |
    | | | |
    | | | |
    | | | |
    | |BAR| |
    | | | |
    | | | X |
    | X X | | X | +---+
    | X O X | | X X | | 2 |
    | X O O X | | X O X X | +---+
    +12-11-10--9--8--7-------6--5--4--3--2--1-+
    Pip count X: 116 O: 106 X-O: 0-0
    Cube: 2, X own cube
    X to play 31

    ---
    Tim Chow

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From atilamalcok@gmail.com@21:1/5 to All on Tue Jun 7 10:38:11 2022
    5 Haziran 2022 Pazar tarihinde saat 15:14:22 UTC+3 itibarıyla Tim Chow şunları yazdı:
    XGID=-B-Aa-D-CbaC---B---bbabbb-:1:1:1:31:0:0:0:0:10

    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-+
    | X | | O O O O O O |
    | X | | O O O O O |
    | | | |
    | | | |
    | | | |
    | |BAR| |
    | | | |
    | | | X |
    | X X | | X | +---+
    | X O X | | X X | | 2 |
    | X O O X | | X O X X | +---+
    +12-11-10--9--8--7-------6--5--4--3--2--1-+
    Pip count X: 116 O: 106 X-O: 0-0
    Cube: 2, X own cube
    X to play 31

    ---
    Tim Chow
    There are two options for X: race or attack and not ahead in the race.
    Also 3-1 is not a good roll to race. Moreover, after making the 5 point, he will be in an awkward shape in the outfield.
    11/10, 6/3* puts O on the bar against a three-point board. If O fails to enter with 9/36 probability, the distribution of X's builders is not bad and he can successfully continue the attack. The probability of being hit is 11/36, but the blot on the 21
    point somehow tolerates that risk. Also, most of the remaining 16/36 work for X.

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Timothy Chow@21:1/5 to All on Wed Jun 8 08:30:20 2022
    XGID=-B-Aa-D-CbaC---B---bbabbb-:1:1:1:31:0:0:0:0:10

    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-+
    | X | | O O O O O O |
    | X | | O O O O O |
    | | | |
    | | | |
    | | | |
    | |BAR| |
    | | | |
    | | | X |
    | X X | | X | +---+
    | X O X | | X X | | 2 |
    | X O O X | | X O X X | +---+
    +12-11-10--9--8--7-------6--5--4--3--2--1-+
    Pip count X: 116 O: 106 X-O: 0-0
    Cube: 2, X own cube
    X to play 31

    Hitting 11/10* 6/3 gives O 13 shots from the bar. Is it worth the
    risk? X is not that far behind in the pip count and could get another
    chance to hit later. On the other hand, O has a blot in her board,
    and 8/5 6/5 does not clean up X's blot in his own board. I decided
    that O's five-point board was too strong to risk 13 shots, but XG
    strongly disagrees. In Variant 1, I have strengthened O's board,
    and in the Variant 2, I have changed the state of X's board. I think
    Variant 2 is interesting; if X hits, then O has only 12 return shots,
    but they don't require breaking O's outfield point.

    1. Rollout¹ 11/10* 6/3 eq:+0.368
    Player: 56.05% (G:19.73% B:0.67%)
    Opponent: 43.95% (G:18.14% B:0.18%)
    Confidence: ±0.009 (+0.359..+0.376) - [100.0%]

    2. Rollout¹ 8/5 6/5 eq:+0.143 (-0.225)
    Player: 48.84% (G:6.95% B:0.15%)
    Opponent: 51.16% (G:7.18% B:0.11%)
    Confidence: ±0.007 (+0.135..+0.150) - [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

    ---------
    Variant 1
    ---------

    XGID=-B-Aa-D-CbaC---B---cbbb-b-:1:1:1:31:0:0:0:0:10

    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-+
    | X | | O O O O O |
    | X | | O O O O O |
    | | | O |
    | | | |
    | | | |
    | |BAR| |
    | | | |
    | | | X |
    | X X | | X | +---+
    | X O X | | X X | | 2 |
    | X O O X | | X O X X | +---+
    +12-11-10--9--8--7-------6--5--4--3--2--1-+
    Pip count X: 116 O: 112 X-O: 0-0
    Cube: 2, X own cube
    X to play 31

    1. Rollout¹ 8/5 6/5 eq:+0.200
    Player: 51.05% (G:4.56% B:0.07%)
    Opponent: 48.95% (G:4.95% B:0.09%)
    Confidence: ±0.003 (+0.196..+0.203) - [100.0%]

    2. Rollout¹ 11/10* 6/3 eq:+0.179 (-0.020)
    Player: 50.58% (G:13.44% B:0.25%)
    Opponent: 49.42% (G:19.11% B:0.30%)
    Confidence: ±0.005 (+0.175..+0.184) - [0.0%]

    ¹ 5184 Games rolled with Variance Reduction.
    Dice Seed: 271828
    Moves: 3-ply, cube decisions: XG Roller

    eXtreme Gammon Version: 2.19.207.pre-release

    ---------
    Variant 2
    ---------

    XGID=---Ca-D-CbaC---B---bbabbb-:1:1:1:31:0:0:0:0:10

    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-+
    | X | | O O O O O O |
    | X | | O O O O O |
    | | | |
    | | | |
    | | | |
    | |BAR| |
    | | | |
    | | | X |
    | X X | | X X | +---+
    | X O X | | X X | | 2 |
    | X O O X | | X O X | +---+
    +12-11-10--9--8--7-------6--5--4--3--2--1-+
    Pip count X: 120 O: 106 X-O: 0-0
    Cube: 2, X own cube
    X to play 31

    1. Rollout¹ 8/5 6/5 eq:+0.132
    Player: 48.21% (G:6.64% B:0.24%)
    Opponent: 51.79% (G:7.14% B:0.08%)
    Confidence: ±0.007 (+0.125..+0.140) - [58.1%]

    2. Rollout¹ 11/10* 10/7 eq:+0.131 (-0.001)
    Player: 49.95% (G:12.32% B:0.45%)
    Opponent: 50.05% (G:17.99% B:0.19%)
    Confidence: ±0.008 (+0.124..+0.139) - [41.9%]

    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

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Timothy Chow@21:1/5 to All on Mon Mar 6 08:59:42 2023
    XGID=-b----EAD---bC---d-dba--B-:0:0:1:11:0:0:0:0:10

    Score is X:0 O:0. Unlimited Game
    +13-14-15-16-17-18------19-20-21-22-23-24-+
    | X O | | O O O X |
    | X O | | O O X |
    | X O | | O |
    | O | | O |
    | | | |
    | |BAR| |
    | | | X |
    | X | | X |
    | X | | X |
    | O X | | X O |
    | O X X | | X O |
    +12-11-10--9--8--7-------6--5--4--3--2--1-+
    Pip count X: 156 O: 144 X-O: 0-0
    Cube: 1
    X to play 11

    ---
    Tim Chow

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Robert Zimmerman@21:1/5 to Timothy Chow on Mon Mar 6 14:35:13 2023
    On Monday, March 6, 2023 at 8:59:44 AM UTC-5, Timothy Chow wrote:
    XGID=-b----EAD---bC---d-dba--B-:0:0:1:11:0:0:0:0:10

    Score is X:0 O:0. Unlimited Game
    +13-14-15-16-17-18------19-20-21-22-23-24-+
    | X O | | O O O X |
    | X O | | O O X |
    | X O | | O |
    | O | | O |
    | | | |
    | |BAR| |
    | | | X |
    | X | | X |
    | X | | X |
    | O X | | X O |
    | O X X | | X O |
    +12-11-10--9--8--7-------6--5--4--3--2--1-+
    Pip count X: 156 O: 144 X-O: 0-0
    Cube: 1
    X to play 11

    ---
    Tim Chow

    Both moves accomplish a few things, and to me those things are hard to add up and compare. I would make the four prime. O ends up having more difficult 5s and 6s to play than when you hit.
    Bob

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Timothy Chow@21:1/5 to All on Thu Mar 9 09:28:36 2023
    XGID=-b----EAD---bC---d-dba--B-:0:0:1:11:0:0:0:0:10

    Score is X:0 O:0. Unlimited Game
    +13-14-15-16-17-18------19-20-21-22-23-24-+
    | X O | | O O O X |
    | X O | | O O X |
    | X O | | O |
    | O | | O |
    | | | |
    | |BAR| |
    | | | X |
    | X | | X |
    | X | | X |
    | O X | | X O |
    | O X X | | X O |
    +12-11-10--9--8--7-------6--5--4--3--2--1-+
    Pip count X: 156 O: 144 X-O: 0-0
    Cube: 1
    X to play 11

    I was concerned that O's offensive position was getting too strong,
    so I hit. But XG hates my play. See the variant for what it takes
    to justify hitting.

    1. Rollout¹ 8/7(2) 6/5(2) eq:+0.248
    Player: 56.52% (G:17.76% B:1.16%)
    Opponent: 43.48% (G:15.72% B:0.94%)
    Confidence: ±0.014 (+0.234..+0.262) - [100.0%]

    2. Rollout¹ 8/7 6/5(3) eq:+0.209 (-0.039)
    Player: 55.74% (G:17.33% B:1.21%)
    Opponent: 44.26% (G:16.17% B:0.96%)
    Confidence: ±0.016 (+0.194..+0.225) - [0.0%]

    3. Rollout¹ 24/23 8/7 6/5(2) eq:+0.180 (-0.068)
    Player: 55.69% (G:16.87% B:1.11%)
    Opponent: 44.31% (G:17.95% B:0.61%)
    Confidence: ±0.015 (+0.165..+0.195) - [0.0%]

    4. Rollout¹ 24/21* 8/7 eq:+0.075 (-0.173)
    Player: 52.02% (G:14.80% B:1.06%)
    Opponent: 47.98% (G:14.84% B:0.60%)
    Confidence: ±0.016 (+0.059..+0.091) - [0.0%]

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

    eXtreme Gammon Version: 2.19.211.pre-release

    -------
    Variant
    -------

    XGID=-b----EAD---bC---cbcba--B-:0:0:1:11:0:0:0:0:10

    Score is X:0 O:0. Unlimited Game
    +13-14-15-16-17-18------19-20-21-22-23-24-+
    | X O O | | O O O X |
    | X O O | | O O X |
    | X O | | O |
    | | | |
    | | | |
    | |BAR| |
    | | | X |
    | X | | X |
    | X | | X |
    | O X | | X O |
    | O X X | | X O |
    +12-11-10--9--8--7-------6--5--4--3--2--1-+
    Pip count X: 156 O: 144 X-O: 0-0
    Cube: 1
    X to play 11

    1. Rollout¹ 24/21* 8/7 eq:-0.186
    Player: 45.54% (G:13.25% B:0.91%)
    Opponent: 54.46% (G:16.10% B:0.76%)
    Confidence: ±0.012 (-0.198..-0.175) - [100.0%]

    2. Rollout¹ 24/23 8/7 6/5(2) eq:-0.217 (-0.030)
    Player: 46.56% (G:13.76% B:0.90%)
    Opponent: 53.44% (G:22.27% B:1.06%)
    Confidence: ±0.012 (-0.228..-0.205) - [0.0%]

    3. Rollout¹ 8/7(2) 6/5(2) eq:-0.226 (-0.040)
    Player: 45.11% (G:14.10% B:0.86%)
    Opponent: 54.89% (G:19.34% B:1.24%)
    Confidence: ±0.012 (-0.238..-0.214) - [0.0%]

    ¹ 2592 Games rolled with Variance Reduction.
    Dice Seed: 271828
    Moves: 3-ply, cube decisions: XG Roller

    eXtreme Gammon Version: 2.19.211.pre-release

    ---
    Tim Chow

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From pepstein5@gmail.com@21:1/5 to Robert Zimmerman on Thu Mar 9 10:13:07 2023
    On Monday, March 6, 2023 at 10:35:15 PM UTC, Robert Zimmerman wrote:
    On Monday, March 6, 2023 at 8:59:44 AM UTC-5, Timothy Chow wrote:
    XGID=-b----EAD---bC---d-dba--B-:0:0:1:11:0:0:0:0:10

    Score is X:0 O:0. Unlimited Game +13-14-15-16-17-18------19-20-21-22-23-24-+
    | X O | | O O O X |
    | X O | | O O X |
    | X O | | O |
    | O | | O |
    | | | |
    | |BAR| |
    | | | X |
    | X | | X |
    | X | | X |
    | O X | | X O |
    | O X X | | X O |
    +12-11-10--9--8--7-------6--5--4--3--2--1-+
    Pip count X: 156 O: 144 X-O: 0-0
    Cube: 1
    X to play 11

    ---
    Tim Chow
    Both moves accomplish a few things, and to me those things are hard to add up and compare. I would make the four prime. O ends up having more difficult 5s and 6s to play than when you hit.
    Bob

    I think you misunderstand the problem. I also find such problem statements unclear and I've even started a thread about this formulation for quiz problems.
    The actual problem statement is: "X to play 11." However, "Hit or make the 5 pt" is not the problem statement but a way of framing the question or explaining
    the topic that this quiz covers.
    If there was only one sensible way of making the four prime, your answer would be fine. However, there seem to be lots of plausible aces after 8/7 6/5(2).
    If I knew that making the four prime was correct (I don't know whether I would have realised this or not), then my additional ace would be 24/23. It seems
    a useful split to me and I don't see that the back checkers have been made vulnerable. How bad is that?

    Paul

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From pepstein5@gmail.com@21:1/5 to peps...@gmail.com on Thu Mar 9 11:56:34 2023
    On Thursday, March 9, 2023 at 6:13:08 PM UTC, peps...@gmail.com wrote:
    On Monday, March 6, 2023 at 10:35:15 PM UTC, Robert Zimmerman wrote:
    On Monday, March 6, 2023 at 8:59:44 AM UTC-5, Timothy Chow wrote:
    XGID=-b----EAD---bC---d-dba--B-:0:0:1:11:0:0:0:0:10

    Score is X:0 O:0. Unlimited Game +13-14-15-16-17-18------19-20-21-22-23-24-+
    | X O | | O O O X |
    | X O | | O O X |
    | X O | | O |
    | O | | O |
    | | | |
    | |BAR| |
    | | | X |
    | X | | X |
    | X | | X |
    | O X | | X O |
    | O X X | | X O |
    +12-11-10--9--8--7-------6--5--4--3--2--1-+
    Pip count X: 156 O: 144 X-O: 0-0
    Cube: 1
    X to play 11

    ---
    Tim Chow
    Both moves accomplish a few things, and to me those things are hard to add up and compare. I would make the four prime. O ends up having more difficult 5s and 6s to play than when you hit.
    Bob
    I think you misunderstand the problem. I also find such problem statements unclear and I've even started a thread about this formulation for quiz problems.
    The actual problem statement is: "X to play 11." However, "Hit or make the 5 pt" is not the problem statement but a way of framing the question or explaining
    the topic that this quiz covers.
    If there was only one sensible way of making the four prime, your answer would be fine. However, there seem to be lots of plausible aces after 8/7 6/5(2).
    If I knew that making the four prime was correct (I don't know whether I would have realised this or not), then my additional ace would be 24/23. It seems
    a useful split to me and I don't see that the back checkers have been made vulnerable. How bad is that?

    Paul

    Sorry, "how bad is that?" is already answered by the rollout.

    Paul

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Robert Zimmerman@21:1/5 to peps...@gmail.com on Thu Mar 9 14:07:39 2023
    On Thursday, March 9, 2023 at 1:13:08 PM UTC-5, peps...@gmail.com wrote:
    On Monday, March 6, 2023 at 10:35:15 PM UTC, Robert Zimmerman wrote:
    On Monday, March 6, 2023 at 8:59:44 AM UTC-5, Timothy Chow wrote:
    XGID=-b----EAD---bC---d-dba--B-:0:0:1:11:0:0:0:0:10

    Score is X:0 O:0. Unlimited Game +13-14-15-16-17-18------19-20-21-22-23-24-+
    | X O | | O O O X |
    | X O | | O O X |
    | X O | | O |
    | O | | O |
    | | | |
    | |BAR| |
    | | | X |
    | X | | X |
    | X | | X |
    | O X | | X O |
    | O X X | | X O |
    +12-11-10--9--8--7-------6--5--4--3--2--1-+
    Pip count X: 156 O: 144 X-O: 0-0
    Cube: 1
    X to play 11

    ---
    Tim Chow
    Both moves accomplish a few things, and to me those things are hard to add up and compare. I would make the four prime. O ends up having more difficult 5s and 6s to play than when you hit.
    Bob
    I think you misunderstand the problem. I also find such problem statements unclear and I've even started a thread about this formulation for quiz problems.
    The actual problem statement is: "X to play 11." However, "Hit or make the 5 pt" is not the problem statement but a way of framing the question or explaining
    the topic that this quiz covers.
    If there was only one sensible way of making the four prime, your answer would be fine. However, there seem to be lots of plausible aces after 8/7 6/5(2).
    If I knew that making the four prime was correct (I don't know whether I would have realised this or not), then my additional ace would be 24/23. It seems
    a useful split to me and I don't see that the back checkers have been made vulnerable. How bad is that?

    Paul

    Yes and yes.

    I did not split for the last 1 as that would have given O good 5s (I though making some 5s and 6s hard to play for O was the road to the right play). My play was 8/7(2) 6/5(2). (6/5(3) is unnecessarily semi-killing a checker).
    After looking at Paul's variant, I don't think trying to kill good 6's and 5's had anything to do with what makes the better play better. Rather, it's apparently that making the 5 point is especially powerful when it combines with the bar point, so
    strong that it beats the hit by a lot. To illustrate, I made some variants.

    Bob

    Variant 1
    -------------------------------------------------------- XGID=-b----E-D---bD---d-dba--B-:0:0:1:31:0:0:0:0:10

    Score is X:0 O:0. Unlimited Game
    +24-23-22-21-20-19------18-17-16-15-14-13-+
    | X O O O | | O X |
    | X O O | | O X |
    | O | | O X |
    | O | | O X |
    | | | |
    | |BAR| |
    | X | | |
    | X | | X |
    | X | | X |
    | O X | | X O |
    | O X | | X O |
    +-1--2--3--4--5--6-------7--8--9-10-11-12-+
    Pip count X: 162 O: 144 X-O: 0-0
    Cube: 1
    X to play 31

    1. XG Roller++ 24/23 24/21* eq:-0.241
    Player: 45.00% (G:11.15% B:0.60%)
    Opponent: 55.00% (G:17.82% B:0.63%)

    2. XG Roller++ 8/5 6/5 eq:-0.272 (-0.031)
    Player: 44.38% (G:12.35% B:0.54%)
    Opponent: 55.62% (G:19.19% B:1.30%)

    eXtreme Gammon Version: 2.10


    Variant 2
    ---------------------------------------------------- XGID=-b----DBC---bD---d-dba--B-:0:0:1:31:0:0:0:0:10

    Score is X:0 O:0. Unlimited Game
    +24-23-22-21-20-19------18-17-16-15-14-13-+
    | X O O O | | O X |
    | X O O | | O X |
    | O | | O X |
    | O | | O X |
    | | | |
    | |BAR| |
    | | | |
    | X | | |
    | X | | X |
    | O X | | X X O |
    | O X | | X X O |
    +-1--2--3--4--5--6-------7--8--9-10-11-12-+
    Pip count X: 162 O: 144 X-O: 0-0
    Cube: 1
    X to play 31

    1. XG Roller++ 8/5 6/5 eq:+0.184
    Player: 55.63% (G:15.80% B:0.94%)
    Opponent: 44.37% (G:15.64% B:0.95%)

    2. XG Roller++ 24/21* 8/7 eq:+0.086 (-0.097)
    Player: 52.76% (G:13.37% B:0.76%)
    Opponent: 47.24% (G:13.87% B:0.51%)

    eXtreme Gammon Version: 2.10

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Timothy Chow@21:1/5 to peps...@gmail.com on Sat Mar 11 10:37:26 2023
    On 3/9/2023 1:13 PM, peps...@gmail.com wrote:
    If I knew that making the four prime was correct (I don't know whether I would have realised this or not), then my additional ace would be 24/23. It seems
    a useful split to me and I don't see that the back checkers have been made vulnerable. How bad is that?

    After making the four-prime, X is ahead in the priming battle
    and behind in the race. O wants to attack or race, so splitting
    is bad for X. Splitting would make more sense if O's game plan
    were to prime or if X's game plan were to race.

    ---
    Tim Chow

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)