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3NT lead problem #12983

#1 User is offline   whereagles 

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Posted 2014-September-26, 04:19

Hi all, see if you get this one right.

Venue: open team trials, training session. Thus top opponents, obviously. IMP scoring.


Auction:
1 = either (1) natural 4+ cards unbalanced or (2) preparatory with balanced 12-14 H (can be 2+ clubs).
1 = 4+ hearts.
1 = 3 hearts, normally min hand.
2 = GF relay.
2 = nat.
3 = stopper ask.

Yer lead?
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#2 User is offline   the hog 

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Posted 2014-September-26, 07:05

small D
"The King of Hearts a broadsword bears, the Queen of Hearts a rose." W. H. Auden.
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#3 User is offline   eagles123 

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Posted 2014-September-26, 12:13

spade
"definitely that's what I like to play when I'm playing standard - I want to be able to bid diamonds because bidding good suits is important in bridge" - Meckstroth's opinion on weak 2 diamond
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#4 User is offline   Jinksy 

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Posted 2014-September-26, 13:15

Small for me. A passed P's unlikely to have good enough s to set the contract, and with LHO sounding balanced, P shouldn't have more than 3Ss, just in case I was feeling fanciful. If the D lead carves a trick, we probably weren't ever setting it.
The "4 is a transfer to 4" award goes to Jinksy - PhilKing
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#5 User is offline   Lord Molyb 

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Posted 2014-September-26, 13:22

small diamond for me too
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#6 User is offline   1eyedjack 

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Posted 2014-September-26, 13:39

Hello

I chose that:

Declarer had 13-18 HCP. Outside that range he would either have made some further slam move or not game forced.
Declarer had fewer than 5 Spades and precisely 4 Hearts, or would have played in known major fit. Not guaranteed but close enough.
Declarer had fewer than 2 of top 3 honours in D (to justify asking)
Dummy had at least 1 of top 3 honours in D (to justify accepting)
Dummy had 12-14 bal with 4 Spades and 3 Hearts.
Partner completely random in context.

Dealt 10000 matching deals (took 15812246 deals to achieve it). D/D result of alternative leads are:

Lead ........ % set ......... Expected tricks

D8 ...........8.18% ......... 2.70
C9 ......... 6.16% ............ 2.59
DK ........ 6.02% ............ 2.32
S4 ........ 5.66% ............ 2.60
S6 ........ 5.64% ............ 2.60
ST ........ 4.51% ............ 2.51
H5 ........ 3.38% ............ 2.35
H2 ........ 3.37% ............ 2.35
H8 ........ 3.00% ............ 2.30
HQ ........ 1.15% ............ 1.93





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.

Psyche (pron. sahy-kee): The human soul, spirit or mind (derived, personification thereof, beloved of Eros, Greek myth).
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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2000 years earlier: "morituri te salutant"

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#7 User is offline   whereagles 

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Posted 2014-September-26, 14:09

@1eyedjack: your constraints are a bit confusing. Opener is the declarer.. I think you got it the other way around.
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#8 User is offline   1eyedjack 

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Posted 2014-September-26, 18:31

View Postwhereagles, on 2014-September-26, 14:09, said:

@1eyedjack: your constraints are a bit confusing. Opener is the declarer.. I think you got it the other way around.


You are right. My bad.

I have swapped declarer and dummy in the previous example and re-run.

Dealt 10000 matching deals (took 15674724 deals to achieve it). D/D result of alternative leads are:

Lead ........ % set ......... Expected tricks

D8 ...........6.15% ......... 2.61
C9 ......... 5.34% ............ 2.57
S4 ........ 4.93% ............ 2.57
S6 ........ 4.86% ............ 2.56
DK ........ 4.50% ............ 2.20
H2 ........ 3.30% ............ 2.41
H5 ........ 3.23% ............ 2.40
ST ........ 3.00% ............ 2.33
H8 ........ 2.68% ............ 2.35
HQ ........ 1.60% ............ 2.18



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.

Psyche (pron. sahy-kee): The human soul, spirit or mind (derived, personification thereof, beloved of Eros, Greek myth).
Masterminding (pron. mPosted ImagesPosted ImagetPosted Imager-mPosted ImagendPosted Imageing) tr. v. - Any bid made by bridge player with which partner disagrees.

"Gentlemen, when the barrage lifts." 9th battalion, King's own Yorkshire light infantry,
2000 years earlier: "morituri te salutant"

"I will be with you, whatever". Blair to Bush, precursor to invasion of Iraq
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#9 User is offline   Lord Molyb 

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Posted 2014-September-26, 23:03

@1eyedjack: in which scenarios would the 4 lead gain over the 6? :huh:
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#10 User is offline   1eyedjack 

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Posted 2014-September-27, 01:57

View PostLord Molyb, on 2014-September-26, 23:03, said:

@1eyedjack: in which scenarios would the 4 lead gain over the 6? :huh:


Hmm, I could have exported the output into a pbn file, loaded it into DDS, filtered the 10K hands as much as possible and then hunted through the remainder, for what appears to be the single hand that makes a difference, based on the spread of %.

Not going to attempt that. Not sure that I can reproduce the data if I fail to pbn it first time. That is a more interesting point, actually, and will look into it. Need to be able to save the random number seed in the .ini file.

My guess is that declarer had 4 card Spade suit including the Spade 5. Leading the 6 somehow promoted the 5.



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.

Psyche (pron. sahy-kee): The human soul, spirit or mind (derived, personification thereof, beloved of Eros, Greek myth).
Masterminding (pron. mPosted ImagesPosted ImagetPosted Imager-mPosted ImagendPosted Imageing) tr. v. - Any bid made by bridge player with which partner disagrees.

"Gentlemen, when the barrage lifts." 9th battalion, King's own Yorkshire light infantry,
2000 years earlier: "morituri te salutant"

"I will be with you, whatever". Blair to Bush, precursor to invasion of Iraq
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#11 User is offline   whereagles 

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Posted 2014-September-27, 02:33

So that seems to have settled it: diamond is the winner.

And it is so in practice, because opponents had Jx in dummy opposite declarer's "stopper" which consisted of Qx tight :)

If you were to "try" for something more fancy, like leading the club 9 on grounds that pard "could have doubled 3 with AT9xx", you'd end up seeing declarer making an overtrick :) Two things warn against this: (1) pard is a passed hand, so you're probably not going to beat this on a passive lead, and (2) partner had a chance to double the 2 relay with a bunch of those.

Thx all.
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