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Rollout and analysis: 5pt or hit?

Posted By: Timothy Chow
Date: Monday, 27 October 2014, at 3:31 p.m.

In Response To: 5pt or hit? (Timothy Chow)

When blitzing, I've found that it's usually better to make a home-board point than to hit a second checker. There are exceptions of course. Usually, the stronger your board, the more eager you are to make a new point; for example, making a fifth point creates 9 extra dancing rolls while making a second point creates only 3 extra dancing rolls. A closeout is usually a no-brainer (unless you're horribly primed on the other side of the board), making a five-point board is rarely wrong, and making a four-point board is usually right.

Here, as a couple of respondents noted, the computer prefers making the 5pt at most scores. But it's gammon go. How does that change the picture?

It isn't always that case that hitting more checkers wins more gammons. In fact, in many early-game situations it's the opposite: making the home-board point is more gammonish while hitting wins more often. Usually the best way to win a gammon is to achieve a closeout, and the more home-board points you have, the easier a closeout tends to be.

However, White is anchored in this position. A closeout isn't going to happen. Sending the extra checker back is the more gammonish play here.

I couldn't find any good way of unanchoring White without doing violence to the position in other ways, but by way of illustration, I have rolled out a variant position below in which White is not anchored. Making the 5pt still isn't more gammonish, but it's very close, and the extra wins push 8/5 6/5 on top of the rollout in the variant.

		White is Player 2 score: 1 pip: 156 2 point match Crawford pip: 111 score: 0 Blue is Player 1
XGID=abBB--DBAA--cB---a-dAb-b--:0:0:1:31:0:1:1:2:10
Blue to play 31

1.	Rollout1	20/17* 17/16	eq: +1.242
	Player: Opponent: 73.44% (G:38.63% B:21.82%) 26.56% (G:4.20% B:0.34%) Conf.: ± 0.009 (+1.233...+1.250) - [100.0%] Duration: 10 minutes 20 seconds
2.	Rollout1	8/5 6/5	eq: +1.204 (-0.037)
	Player: Opponent: 77.07% (G:33.14% B:15.62%) 22.93% (G:3.27% B:0.28%) Conf.: ± 0.009 (+1.196...+1.213) - [0.0%] Duration: 8 minutes 57 seconds
3.	Rollout1	20/17* 8/7	eq: +1.171 (-0.071)
	Player: Opponent: 72.61% (G:35.92% B:17.97%) 27.39% (G:3.71% B:0.34%) Conf.: ± 0.009 (+1.162...+1.179) - [0.0%] Duration: 10 minutes 09 seconds
4.	Rollout1	20/17* 9/8	eq: +1.161 (-0.081)
	Player: Opponent: 72.46% (G:35.58% B:18.66%) 27.54% (G:3.54% B:0.37%) Conf.: ± 0.008 (+1.153...+1.169) - [0.0%] Duration: 9 minutes 19 seconds
1 1296 Games rolled with Variance Reduction. Dice Seed: 271828 Moves: 3-ply, cube decisions: XG Roller

eXtreme Gammon Version: 2.10, MET: Kazaross XG2

---

Variant:

		White is Player 2 score: 1 pip: 145 2 point match Crawford pip: 111 score: 0 Blue is Player 1
XGID=aaBB--DBAA--dB---a-dAb-b--:0:0:1:31:0:1:1:2:10
Blue to play 31

1.	Rollout1	8/5 6/5	eq: +1.489
	Player: Opponent: 80.68% (G:43.74% B:4.92%) 19.32% (G:4.30% B:0.47%) Conf.: ± 0.006 (+1.483...+1.495) - [100.0%] Duration: 7 minutes 25 seconds
2.	Rollout1	20/17* 17/16	eq: +1.457 (-0.031)
	Player: Opponent: 78.26% (G:44.60% B:7.52%) 21.74% (G:4.84% B:0.65%) Conf.: ± 0.007 (+1.450...+1.464) - [0.0%] Duration: 9 minutes 15 seconds
1 1296 Games rolled with Variance Reduction. Dice Seed: 271828 Moves: 3-ply, cube decisions: XG Roller

eXtreme Gammon Version: 2.10, MET: Kazaross XG2

---

Original position for money:

		White is Player 2 score: 0 pip: 156 Unlimited Game pip: 111 score: 0 Blue is Player 1
XGID=abBB--DBAA--cB---a-dAb-b--:1:-1:1:31:0:0:0:0:10
Blue to play 31

1.	Rollout1	8/5 6/5	eq: +0.819
	Player: Opponent: 76.77% (G:35.96% B:5.24%) 23.23% (G:3.24% B:0.12%) Conf.: ± 0.008 (+0.811...+0.827) - [99.8%] Duration: 11 minutes 04 seconds
2.	Rollout1	20/17* 17/16	eq: +0.800 (-0.019)
	Player: Opponent: 73.30% (G:41.96% B:6.96%) 26.70% (G:4.05% B:0.24%) Conf.: ± 0.010 (+0.790...+0.810) - [0.2%] Duration: 12 minutes 14 seconds
1 1296 Games rolled with Variance Reduction. Dice Seed: 271828 Moves: 3-ply, cube decisions: XG Roller

eXtreme Gammon Version: 2.10

Messages In This Thread

• 5pt or hit?
  Timothy Chow -- Sunday, 26 October 2014, at 5:48 p.m.
  • 5pt or hit?
    David Rennie -- Sunday, 26 October 2014, at 6:02 p.m.
  • 5pt or hit?
    MishyPoo -- Sunday, 26 October 2014, at 8:43 p.m.
  • 5pt or hit?
    ah_clem -- Sunday, 26 October 2014, at 11:16 p.m.
  • 5pt or hit?
    neilkaz -- Monday, 27 October 2014, at 12:33 a.m.
  • 5pt or hit?
    David Presser -- Monday, 27 October 2014, at 5:33 a.m.
  • Rollout and analysis: 5pt or hit?
    Timothy Chow -- Monday, 27 October 2014, at 3:31 p.m.