[Jinksy]

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What would you lead against this? Also, if your first choice suit were prohibited, what would be your second choice? Butler IMPs.

[mgoetze]

It seems exceedingly unlikely that any good would come of leading a heart. Spade seems very aggressive - I suppose it is a consideration at IMPs, but it is not for me. Minors all the way.

[BillPatch]

Bird-Anthias found that a singleton spade was often a good lead on this auction. They are assuming that the opener will return to spades over 3NT anytime they have more than three spades, and responder has promised exactly five, so we can deduce that partner also has five. Since partner's spade length is over dummy, a spade rates to be a safe lead. Richard Pavlicek on his web site recommends that when the opener on this bidding should always stay in NT at IMPs with any 4-3-3-3, regardless of 4 card suit. I respect his sims, I intend to follow this advice. I suspect that at least some actively playing experts might also adopt Pavlicek's theory, against them I would play my second choice low diamond. Then I would lead a diamond because my extreme weakness dictates a short suit trying to set up partner's suit, and I prefer a diamond since if I hit partner's long suit my honor card may help establish that suit.

[steve2005]

Leading spades on the hope p has 5 spades. hearts is a waste of time u have no entry. Minor might work but is guess which one.

[WesleyC]

I ran a quick sim of 10,000 hands:

## West has [6 J97653 J85 962]

## North has 10-16 HCP, and exactly 5 spades.
## North doesn't have 4+H, 5+m or a 5044

## South can have 13 HCP and a 5+m. Otherwise 14-16 HCP.
## South is semi-balanced* with exactly 2 spades or 4333 shape.
## (*includes all 6m & 5M hands without a shortage, including all 6322 & 5422s).

Results: http://imgur.com/OKaOiPA

My main conclusion is that because the minors suits sit so favourably for declarer, 3NT always almost makes and your lead is rarely going to matter.

However, it does seems like leading either of the minors (pretty much at random) is your best option.

Finally, here a sample of the first 10 (random) hands where a club lead is the only lead to beat the contract.
http://textuploader.com/a0m5p

[Jinksy]

One other thing that tips it further towards a minor is P's inability to X for a spade lead. In many cases it's probably because he just doesn't have a good enough hand, but where we are setting the contract by establishing a suit, it suggests that suit won't be spades.

Btw Wesley, I really appreciate your regular sims and your scruples to give their parameters.

[WesleyC]

 Jinksy, on 2015-August-08, 06:29, said:

Btw Wesley, I really appreciate your regular sims and your scruples to give their parameters.

Cheers Jinksy, as usual you shouldn't take this sim as conclusive proof.

But especially an abstract situation like this, unless you can find a serious problem with the conditions, I'd trust these result over most hand waving arguments.

[Jinksy]

Agree on both counts. But it gives me some ammo for the dispute with my P, who thought I should lead a ♥, where I thought that was my least favourite lead

[Siegmund]

The answer is somewhat sensitive to the sim conditions. I interpreted responder as never having a singleton, rather than just not 5044. (The truth is somewhere in between; some but not all 5143s will bid the 4-card minor.)

At MPs the club was a clear winner by a small margin (71% chance of still being able to achieve par after a club lead, vs. 68% for a diamond, 66% for the spade, and 64% for the heart). At IMPs it was pretty much a tie between a low club and low diamond, with an average loss vs. par of 0.98 imps. A low heart was -1.05, and a low spade was -1.18, almost as bad as the DJ or HJ.
I had a 6% chance of setting the contract with a heart, diamond, or club, only 4% with the spade.

If dummy is not going to have a singleton heart, the chances of running hearts get far better (partner has 3 hearts, or has 2 high hearts and good enough diamonds the DJ is an entry). Correspondingly the chance of a spade being safe is hurt when opener can be 3433 (and I think he can be.)

[Jinksy]

 Siegmund, on 2015-August-08, 09:48, said:

If dummy is not going to have a singleton heart, the chances of running hearts get far better (partner has 3 hearts, or has 2 high hearts and good enough diamonds the DJ is an entry).

I don't buy this. For Hs to be setuppable with 2, they'd have to be the AK. Then for Ds to be good enough to put me in, he needs AKQx and an outside entry, or A(K/Q)x and two outside entries. I don't see the opps bidding game missing all that.

[Siegmund]

Tried one more experiment - limited opener to being 3(433), 2(533), or 2(443), rather than allowing all the 2542 and 2263 type hands. This sharpened the differences more: C losing 0.64 imps, D losing 0.70 imps, S losing 1 imp, H losing 1.16. Setting the contract goes from C 7%, D 6.5%, S 4.3%, H 3.3%.

(Not allowing 2254/2245 removes a whole lot of the hands where a heart lead is successful - which pretty much needs opener to either have a doubleton or not have an honor.)

[WesleyC]

Perhaps unsurprisingly, if you change the hand slightly by taking away a heart and adding a second spade, prospects for beating 3NT are much improved (and the heart lead is clear)!

DD analysis for [62 J9763 J85 962] is:

http://imgur.com/vpQR3l3

[BillPatch]

Thanks for the sims. Sorry for the bad hand waving. Checking back with Bird-Anthias I see that they warn against leading their major. I misremembered this because their sample hands included a high proportion of such leads. Mea culpa.

[KurtGodel]

I feel like a lot of the time it is right to lead a spade, partner will have doubled.