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Percentage Play

#1 User is offline   lamford 

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Posted 2021-October-09, 10:24


Suitplay bleeped my line of play here, but I am not so sure. How would you play 6NT on the ten of hearts lead?

We still do not know one thousandth of one percent of what nature has revealed to us. - Albert Einstein
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#2 User is offline   LBengtsson 

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Posted 2021-October-09, 13:52

its all or nothing on the ♣ suit for 4 tricks as I see it. you can play from dummy and finesse ♣10 on first round, or you can lead to ♣Q and finesse ♣10 on second round. much smaller percentage to pin the ♣J or ♣9 on some distributions. I would take second option and lead to ♣Q and then finesse ♣10 on way back.
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#3 User is offline   steve2005 

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Posted 2021-October-09, 15:09

small to Q♣ then small towards the ten
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#4 User is offline   sfi 

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Posted 2021-October-09, 16:37

Low to the 10 feels right. I get to pick up stiff 9 on my left.
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#5 User is online   smerriman 

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Posted 2021-October-09, 17:02

Low to the 10 works if West has singleton 9 or East has singleton J. Leading to the queen works if West has AJ. The former is more likely.

However, Suitplay would also go with the percentages so there must be a catch..
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#6 User is offline   Winstonm 

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Posted 2021-October-09, 17:17

The only other remote chance I can see is low to the queen allows a possible club/diamond squeeze when west has stiff ace but surely low to the 10 is right as the squeeze is far fetched even if the ace is singleton.
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#7 User is offline   lamford 

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Posted 2021-October-10, 09:36

View PostWinstonm, on 2021-October-09, 17:17, said:

The only other remote chance I can see is low to the queen allows a possible club/diamond squeeze when west has stiff ace but surely low to the 10 is right as the squeeze is far fetched even if the ace is singleton.

Suitplay does indeed give low to the ten as the right action. I don't think this takes into account the power of the closed hand. If you play low to the ten, then you are about 43%. Low to the king is 6% worse. But ....

West has to duck, and play the nine from A9x or you have no losing option. West also has to play the nine from J9x to give you a losing option. And finally East has to play the jack from J9 doubleton. The first of these is impossible, and he cannot duck as it could just give away a no-play contract with South having K8x. If the opponents defend perfectly (but not omnisciently) the two lines are the same. Any slip and low to the king is better.
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#8 User is offline   Winstonm 

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Posted 2021-October-10, 11:08

If west plays the 9 from J93, he is ducking the setting trick.🤔
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#9 User is offline   lamford 

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Posted 2021-October-10, 16:36

View PostWinstonm, on 2021-October-10, 11:08, said:

If west plays the 9 from J93, he is ducking the setting trick.🤔

You misunderstand. When declarer plays low to the king, West must play the nine for J9x and A9x
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#10 User is offline   nige1 

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Posted 2021-October-10, 16:52

View Postlamford, on 2021-October-10, 09:36, said:

Suitplay does indeed give low to the ten as the right action. I don't think this takes into account the power of the closed hand. If you play low to the ten, then you are about 43%. Low to the king is 6% worse. But .... West has to duck, and play the nine from A9x or you have no losing option. West also has to play the nine from J9x to give you a losing option. And finally East has to play the jack from J9 doubleton. The first of these is impossible, and he cannot duck as it could just give away a no-play contract with South having K8x. If the opponents defend perfectly (but not omnisciently) the two lines are the same. Any slip and low to the king is better.
Paul makes an excellent point about "the power of the closed hand" :) Nobody else seems to have considered it until now :(
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#11 User is online   smerriman 

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Posted 2021-October-10, 18:41

I can see why this is more complex than it originally looked, but I'm not quite following the logic.

You concluded that it's impossible for West to play the 9 from A9x, but that playing 9 from J9x gives you a losing option.

What's the losing option? When we next lead low from hand, if West plays low, we know they couldn't possibly have played the 9 from A9x, so the only option is to duck, and it works. If West plays the J, we cover and set up our 8, so no losing option there either.

It seems non-omniscient defenders *would* have to play the 9 from A9x at least some percentage of the time if they want to improve their chances with J9x too, gambling that declarer doesn't have K8x.
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#12 User is offline   Winstonm 

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Posted 2021-October-10, 20:04

View Postlamford, on 2021-October-10, 16:36, said:

You misunderstand. When declarer plays low to the king, West must play the nine for J9x and A9x


Yes, I was thinking of low to the 10 and forgot you had said to the king. Thanks.
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#13 User is offline   lamford 

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Posted 2021-October-12, 08:29

View Postsmerriman, on 2021-October-10, 18:41, said:

You concluded that it's impossible for West to play the 9 from A9x, but that playing 9 from J9x gives you a losing option.

What's the losing option?

If you play low to the king and West plays low from J9x, you have no choice but to play his partner for Ax and duck the second round. If West plays the nine, you can now play for his partner to have Jx.

It is game theory, yes, with incomplete information. And playing the 9 from A9x will be fatal even when declarer has Kxx without the 8, as you have to win here. I think ALL will win from A9x. If they do play the nine from A9x, I think they will succeed, as "they couldn't possibly have A9x, could they?"
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#14 User is offline   lamford 

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Posted 2021-October-12, 08:42

View PostWinstonm, on 2021-October-09, 17:17, said:

The only other remote chance I can see is low to the queen allows a possible club/diamond squeeze when west has stiff ace but surely low to the 10 is right as the squeeze is far fetched even if the ace is singleton.

And I think the squeeze is still one off?
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#15 User is offline   Winstonm 

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Posted 2021-October-12, 09:07

View Postlamford, on 2021-October-12, 08:42, said:

And I think the squeeze is still one off?



I don't think so...unnecessary is the word. If LHO has a singleton ace, I can pick up the suit for no losers by leading the 8 toward the Q then finessing the 10 next. Posted Image

If the singleton ace is on the right, we are going down. Posted Image
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