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Jacoby Rule (effect)

Posted By: Ray Kershaw
Date: Sunday, 16 August 2015, at 1:29 p.m.

In Response To: Jacoby Rule (effect) (Nack Ballard)

In Feature Position 1, Blue plays safe with the Jacoby Rule for an equity of 0.889 and he plays bold without the Jacoby Rule for an equity of 0.956. The loss of equity due to the Jacoby Rule is thus 0.067.

In my book Backgammon Funfair, I tried to find the position with the greatest loss of equity due to the Jacoby Rule. Below White has rolled 54. The correct safe play with the Jacoby Rule is the safe 7/2, 6/2 with an equity of 1.000. The correct bold play without the Jacoby Rule is 7.3*, 7/2 with an equity of 2.017. The loss of equity due to the Jacoby Rule is 1.017.

(41,472 unlimited cubeful games using XG 2.01, variance reduction, moves 3-ply, cube decisions XG Roller.)

Of course, unlike Nack's positions, this is not a realistic position since with the Jacoby Rule White would have claimed his point long ago.

	is Player 2 score: 0 pip: 198 Unlimited Game Jacoby Beaver pip: 65 score: 0 is Player 1
XGID=cBBaCCCB----baaab-b-b-----:0:0:1:00:0:0:3:0:10
on roll, cube action?

eXtreme Gammon Version: 2.19.208.pre-release

Messages In This Thread

• Jacoby Rule (effect)
  Nack Ballard -- Friday, 14 August 2015, at 7:05 p.m.
  • Jacoby Rule (effect)
    Joe Russell -- Saturday, 15 August 2015, at 2:20 a.m.
  • Jacoby Rule (effect)
    Ray Kershaw -- Sunday, 16 August 2015, at 1:29 p.m.