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61P-33C-21 — No Jacoby, No Beavers — 3-ply XG2 Rollout

Posted By: Taper_Mike
Date: Monday, 16 December 2013, at 7:15 a.m.

In Response To: Catchup #2 - 61P-33C-21? (Stick)

		White is Player 2 score: 0 pip: 155 Unlimited Game pip: 160 score: 0 Blue is Player 1
XGID=----b-EBB---eD---a-eb---B-:0:0:1:21:0:0:0:0:10
Blue to play 21

1.	Rollout1	24/22 6/5	eq: -0.2838
	Player: Opponent: 44.64% (G:9.95% B:0.44%) 55.36% (G:18.93% B:0.81%) Conf.: ±0.0031 (-0.2870...-0.2807) - [100.0%] Duration: 3 hours 54 minutes
2.	Rollout1	24/23 24/22	eq: -0.3005 (-0.0166)
	Player: Opponent: 43.71% (G:8.50% B:0.35%) 56.29% (G:16.85% B:0.51%) Conf.: ±0.0029 (-0.3034...-0.2976) - [0.0%] Duration: 3 hours 38 minutes
3.	Rollout1	7/5 6/5	eq: -0.3044 (-0.0205)
	Player: Opponent: 43.66% (G:9.84% B:0.41%) 56.34% (G:17.57% B:0.75%) Conf.: ±0.0029 (-0.3072...-0.3015) - [0.0%] Duration: 3 hours 30 minutes
4.	Rollout2	24/21	eq: -0.3052 (-0.0214)
	Player: Opponent: 43.61% (G:8.52% B:0.34%) 56.39% (G:16.38% B:0.53%) Conf.: ±0.0041 (-0.3094...-0.3011) - [0.0%] Duration: 1 hour 52 minutes
5.	Rollout2	24/23 13/11	eq: -0.3098 (-0.0259)
	Player: Opponent: 43.63% (G:8.76% B:0.37%) 56.37% (G:17.46% B:0.64%) Conf.: ±0.0042 (-0.3140...-0.3056) - [0.0%] Duration: 1 hour 48 minutes
1 31104 Games rolled with Variance Reduction. Dice Seed: 29647653 Moves: 3-ply, cube decisions: XG Roller 2 15552 Games rolled with Variance Reduction. Dice Seed: 29647653 Moves: 3-ply, cube decisions: XG Roller

Rollout by Taper_Mike 2013-Dec-15 eXtreme Gammon Version: 2.10.199.2658 61P-33C-21-n-tm.xgp n[W V17 P21 U21 S26] "<=31**15 n[W P11 U15 V15 S23] "&e

eXtreme Gammon Version: 2.10

We Love the Wild Ones!

A couple of the features identified in Backgammon Openings, Book A (Ballard/Weaver, 2007) as prerequisites for a “wild” play (W = 24/22 6/5) are present in this position. Blue’s 6pt is stacked. White owns a strong anchor.

Some others are not, the most important of which concerns the race. Slotting risks less when Blue already trails in the race. Here, after factoring in the 4-pip, on-roll advantage, Blue trails by only 1 pip.

I have long noted that when W is on the list of candidates, U and/or V are often close alternatives. S is also a frequent alternative to W, but I would say not as often as U. Here it is easy to see why V outpaces U. Playing two up gives more return shots when your opponent hits from his 6pt, but is forced to leave a blot on his 8pt.

The fact of White’s advanced anchor and strong inner board makes some sort of split necessary here. That is the primary reason P rolls out behind W and V. In most cases, owning the 5pt with a slot on 7pt is better than the reverse. When you toss in the split, however, the balance is tipped in favor of W.

Considering the same strengths, White’s high anchor and strong board, I can understand why a split to the 23pt does not fare as well as one to the 22pt or 21pt. For that reason, S is likely to be worse than U or V.

So, having rejected P and S, begin by moving one checker 24/22. If you can get that far over the board, then the final decision comes down to playing the other back checker to the 23pt or else slotting the 5pt. Whether that is enough to get you to the slot is not clear.

 

61P-33C-21 — Unlimited Games

Bot	Seed	Equity	Nacbracs	Link
GnuBg 0.xx 2-ply	806598955	–279.1	[W P26] /3	Stick
GnuBg 0.xx 2-ply	809263104	–270.6	[W U21 V30 P37 S39] /4**3 2	Chuck Bower
Snowie 4.x.x 3-ply Trunc	[Random seed]	–253	[W P18 S28 V28 U31] ~0.648t — Depth 7	Paul Weaver
GnuBg 0.xx 2-ply Trunc	730073992	–328.318	n[P V8 W12 S13 U15] /0.360t	Taper_Mike
XG 2.10 XGR++ Eval	[XGR++ seed]	–291.9	n[W P11 U15 V15 S23] "&e	Taper_Mike
XG 2.10 3-ply, Cubes: XGR	29647653	–283.8	n[W V17 P21 U21 S26] "<=31**15	Taper_Mike (above)

Key: P = Point [7/5, 6/5], S = Split [24/23, 13/11], U = Up [24/21], V = Variant up [24/23, 24/22], W = Wild [24/22, 6/5]

Explanation of nacbracs

Mike

Messages In This Thread

• Catchup #2 - 61P-33C-21?
  Stick -- Monday, 1 December 2008, at 12:56 p.m.
  • Catchup #2 - 61P-33C-21?
    Coolrey -- Monday, 1 December 2008, at 1:01 p.m.
  • Catchup #2 - 61P-33C-21?
    Matt Cohn-Geier -- Monday, 1 December 2008, at 2:02 p.m.
    • 61P-33C-31
      onur alan -- Wednesday, 11 December 2013, at 7:41 p.m.
      • 61P-33C-31
        Taper_Mike -- Thursday, 12 December 2013, at 1:25 a.m.
      • 61P-33C-31 XG 1k RO
        onur alan -- Friday, 13 December 2013, at 1:45 p.m.
        • 61P-33C-31 — No Jacoby, No Beavers — XGR++ Eval
          Taper_Mike -- Friday, 13 December 2013, at 3:17 p.m.
          • 61P-33C-31 — No Jacoby, No Beavers — XGR++ Eval
            onur alan -- Friday, 13 December 2013, at 4:08 p.m.
            • 61P-33C-31 — No Jacoby, No Beavers — XGR++ Eval
              Philippe Michel -- Friday, 13 December 2013, at 7:26 p.m.
              • XGR++ versus a 1k Rollout
                Taper_Mike -- Friday, 13 December 2013, at 11:23 p.m.
                • XGR++ versus a 1k Rollout
                  onur alan -- Saturday, 14 December 2013, at 8:42 a.m.
                  • XGR++ versus a 1k Rollout
                    Taper_Mike -- Saturday, 14 December 2013, at 11:02 a.m.
        • 61P-33C-31 XG 5k RO
          onur alan -- Saturday, 14 December 2013, at 11:27 a.m.
      • 61P-33C-31 GNU 7k RO
        Philippe Michel -- Friday, 13 December 2013, at 7:15 p.m.
  • Catchup #2 - 61P-33C-21?
    neilkaz -- Monday, 1 December 2008, at 7:56 p.m.
  • 61P-33C-21 — No Jacoby, No Beavers — 3-ply XG2 Rollout
    Taper_Mike -- Monday, 16 December 2013, at 7:15 a.m.