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BGonline.org Forums
Race%? Shot E% Take?
Posted By: Ian Shaw In Response To: Race%? Shot E% Take? (Mr Majestyk)
Date: Friday, 13 May 2011, at 8:46 a.m.
My initial impression is that this is a comfortable money take. Blue has three landing spots for his midpoint chequers, which is a plus. However, he also has to clear the 11 point, which is exactly 6 pips from the anchor. This blocks White's racing 66 but will also yield shots during the bear in.
Leading 2-away 3-away, White risks 18% to gain 50%, so his raw takepoint is 26.5% and the cube becomes dead. There will be the odd gammon (about 2%) and the gammon value is about 1/2 (32/68) so White needs 27.5% in all. This is much higher than for money, but it still looks takeable to me.
To estimate the racing chances, I can approach it 2 ways. Common to both, I estimate that Blue's open five point will likely remain open, and cost 2 pips over an efficient position, so his pipcount becomes 116 .
- Using Rule 62, point of last take = 116 + 10% + 2 = 129. White is one pip worse than this, so her racing chances must be around 20%.
- A Kleinman count gives 18²/242 = 324/242 ~= 32/24 = 4/3 = 1.33. A value of 1.0 = 76%, and then 0.1 increments up to 1.4 are worth 1%. This puts Blue at 79.3%, or 20.7% for White.
White therefore needs about 8% shot equity to take. Hitting 8% shots means that she will need about 8/30% = 24 direct shots, and (then win from there). Roughly speaking, Blue has three landing spots to on which clear each of the 13 and 11 points. That's 9 rolls, plus a couple extra for other clearing doubles. So Blue can clear each back point cleanly about 1/3 of the time. He gets repeated attempts to do so, and my maths is getting shaky after this, so I can't do the recursive calculations necessary, but it sure looks like White will get enough shots.
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