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What Are the Odds?

#1 User is offline   uva72uva72 

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Posted 2014-September-30, 10:42

My link

Match points, ACBL robot individual

There is a legitimate line for 6NT on this hand, namely finding KJ or KJX onside. My very inexpert calculation concludes that the chance of success upon winning the A is about 12%. However, when West follows with the 8, that chance drops significantly (I'm guessing to a little under 7%) because a number of winning (and losing) combinations have been eliminated.

Then there is the playing-against-the-robots line. Recognizing that the 8 is twice as likely to be from K83 or K84 than from KJ8, you insert Q. Now when you lead the 9 from dummy, West "knows" you have the J (you need it, along with Q, for the 21 HCP promised by your jump to 6NT), so it doesn't matter what West does, so West will, of course, play the K.

Against the robots, this looks like a much better line to me.
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#2 User is offline   1eyedjack 

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Posted 2014-September-30, 13:25

Given the language barrier, Georgi might have trouble appreciating the point being made here, which is essentially:

East's play to the second Spade is irrelevant if 100% faith is placed on South's compliance with systemic expectation for his bidding, which places South with Spade Jack.

That said, for South systemically to have 21 HCP, he requires not just the Spade Jack but also the Heart Queen. East should I think place West with the Heart Queen given the lead of Heart King. That being the case, since South cannot have 21 HCP, should reliance on his holding the Spade Jack be called into question as well?

As soon as you introduce an element of distrust in South's compliance, ie as soon as there is any likelihood greater than 0% that West might conceivably have the Spade Jack, there is no incentive whatever for East to play the Spade King, and a positive incentive, however slight, to play low.

This is a point repeatedly made in the forum, Stephen Tu being one of the principal champions of the cause, and the solution is to introduce an element of distrust in opponents' supposed "promises", even if blind faith is reasonably placed in partner.

I think that it is ironic that GIB puts such faith in honesty when it routinely bids above its weight, promising hands a good 2 points better than actually held.
Psych (pron. saik): A gross and deliberate misstatement of honour strength and/or suit length. Expressly permitted under Law 73E but forbidden contrary to that law by Acol club tourneys.

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Masterminding (pron. mPosted ImagesPosted ImagetPosted Imager-mPosted ImagendPosted Imageing) tr. v. - Any bid made by bridge player with which partner disagrees.

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#3 User is offline   johnu 

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Posted 2014-September-30, 14:46

View Postuva72uva72, on 2014-September-30, 10:42, said:


There is a legitimate line for 6NT on this hand, namely finding KJ or KJX onside. My very inexpert calculation concludes that the chance of success upon winning the A is about 12%. However, when West follows with the 8, that chance drops significantly (I'm guessing to a little under 7%) because a number of winning (and losing) combinations have been eliminated.

Then there is the playing-against-the-robots line. Recognizing that the 8 is twice as likely to be from K83 or K84 than from KJ8, you insert Q. Now when you lead the 9 from dummy, West "knows" you have the J (you need it, along with Q, for the 21 HCP promised by your jump to 6NT), so it doesn't matter what West does, so West will, of course, play the K.

Against the robots, this looks like a much better line to me.


I usually don't give too much thought into analyzing GIB's play. To GIB's credit, I have never seen GIB revoke, but playing 2nd hand high for no reason, 3rd hand low when playing high is the right play, randomly sacrificing important spot or even honor cards which take the guess away for declarer are all too common. You will give yourself a brain tumor trying to make sense out of some of GIB's cardplay.
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