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BGonline.org Forums
Daily Quiz 9/15
Posted By: kruidenbuiltje In Response To: Daily Quiz 9/15 (Daily Quiz)
Date: Friday, 16 September 2011, at 12:54 p.m.
No 1:
An original position. Is it a holding or a backgame? It looks more like a double holding game. The lack of inner board points has as a disadvantage that blue doesn't have a lot of free (playable) pips. Right now he has 8 pips from the midpoint and three pips from the 6 point. So within 2 moves blue will have to throw a double (except D4) or 52. When blue chooses to disengage the midpoint first the white hitchance = (29/36)^2 * 14/36 (4's + 31 + D6)= 25%. Besides this there will be later hits by disengaging the 11-point and hit from the late ace-point, so far it looks like a no double, But ... there is more.
When blue throws a delta 1 (21,32,43) he can make a point, and raise his playable pips. He can also choose to take a small risk (6/36) by using his 8-point checkers as builders, on the first move the effective risk is 22/36 * 6/36 = 10% because of the return on the loose 3-blot. With the extra builder also (42,53,64) and (41,52,63) make an extra point.
The conclusion is that because of the possible increase of pip-playability this position becomes a double-take.
No 2:
Lets start with the pipcount. Say with this pipcount and the blue checkers had no contact anymore. Then it would be Too Good To Double as long as the white checker didn't enter. Because of the 4 extra outfield-crossovers the gammon-chance of a close-out raises from the standard 5% to something near 40%. But with this lot of contact left we have to calculate the chance that white enters and hits. Right now this chance is between 7/36 and 11/36, say about 10/36. But it will decrease with about 3/36 per move. So the total white chance will become somthing like: 11/36* 7/36 + 25/36* 11/36* 4/36 + a little bit = 6% + 2% + ... = say 9%. Add to this a smaal miracle escape + running chance no more than 5% i guess, makes 14% = Double pass.
No 3:
Position +, Race +. So its a double. Normally an anchor,contact and a 5-prime is a pass (Robertie-rule). But with 0ne extra man back a 4-prime is a pass. But here whites extra man back is on the bar, this makes the 3-prime a pass. So double pass in a money game. But since white is behind in the match it's Double Take.
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