Lead Problem H - MSC August

[Mbodell]

IMP all red

[hv=pc=n&s=st4hk83dj43cat843&d=e&v=b&b=10&a=1np2cp2sp3sp4sppp]133|200[/hv]

 

5 different cards chosen by panelists, close to even 4 way split among both panelists and solvers for the top lead.

[mikeh]

I think this is pretty much a guess.

 

About the only suit I would rule out would be diamonds. Jxx is an awful lead, requiring specific holdings to gain a trick and often blowing one, as well as blowing a tempo, tho when the opps strain to bid game after a 1N, tempo is not as important as it usually is.

 

I can see the case for a spade, but on this auction the trump may not be the passive lead we were playing to make. There are a lot of holdings where leading from 10x picks up the suit for declarer.

 

The heart suit is what I would lead....I would lead low. This can blow up as well, but my experience with these leads has been generally pretty good. Leading from a short K when the Ace rates not to be in dummy often gains immediately and, when it doesn't, often ends up not costing a trick...imagine dummy with J10xx and declarer AQx.

 

Clubs...we can lead the Ace and hope to catch a stiff in partner's hand, or we can lead low, hoping for good things either now (partner with Kx for example, or the K in dummy and partner with the Q, or partner with a doubleton and a trump entry, but to me all of these are low percentage, and not assured to win....will partner, with xx in clubs, always win his trump and return clubs?

 

I probably underlead Kings more than most people, so I suspect I am biased here, but the heart is, to me, the best lead.

 

Frankly the other options don't interest me: I don't ever think that way at the table, and I don't think that double dummy assumptions are ever warranted in the actual game.

[Jinksy]

I will be quite surprised if the club ace doesn't win DD. Perfect players love not having a human throw away their control of the hand.

 

At the table I agree with mikeh that it's a guess, but I pretty much have the reverse preference:

 

A heart is my last choice - I barely registered it as an option after first glance.

 

ATxxx has too much chance of blowing the suit wide open for my limited capacity to find the killer switch after seeing dummy. Better players than me would prob do better from it.

 

Leading a S probably won't do much to cut down on ruffs in a 4-4 hand, and has a 3/10 chance of picking up partner's queen (and a little extra of carving a K holding since I have the 10).

 

I don't like leading from Jxx much more than mikeh, but it feels less likely to give away a trick they couldn't pick up anyway than any of the others.

[wank]

diamond seems like the boring obvious choice. ace of clubs to give partner a ruff if you're aggressive (yeah you have the option of switching but absent cheating you'll have no idea whether partner is ruffing or not)

[Phil]

I checked my answers - I led the ♦3.

 

Far from convinced this is the best choice.

[gnasher]

Leading a S probably won't do much to cut down on ruffs in a 4-4 hand, and has a 3/10 chance of picking up partner's queen (and a little extra of carving a K holding since I have the 10).

3/10 is the probability that partner has any 3-card holding including the queen, given that all we know is that he has three cards. However, that's not the probability of picking up his queen.

 

 

To calculate the actual probability of picking up partner's queen you have to exclude layouts where declarer was going to finesse it anyway, and the layouts where partner's holding is strong enough to survive the lead. That means you have to exclude layouts where:

 

- Declarer has the jack

- Dummy has AKJ

- Partner has the jack

- Partner has the king and there was an intrafinesse

- Partner has 98

- Partner has the nine and dummy has HJ

 

Furthermore, we're expecting partner to have about 7/32 of the outstanding high-card strength. The probability has to be reduced to reflect that expectation.

 

I'd guess that the actual chance of picking up partner's queen is in the 2-3% range.

 

[the_clown]

I would lead a diamond hoping not to blow a trick. A ♥ is close second.

[gordontd]

A ♥ is close second.

Maybe even first choice, if you held the card.

[PhilKing]

3/10 is the probability that partner has any 3-card holding including the queen, given that all we know is that he has three cards. However, that's not the probability of picking up his queen.

 

 

To calculate the actual probability of picking up partner's queen you have to exclude layouts where declarer was going to finesse it anyway, and the layouts where partner's holding is strong enough to survive the lead. That means you have to exclude layouts where:

 

- Declarer has the jack

- Dummy has AKJ

- Partner has the jack

- Partner has the king and there was an intrafinesse

- Partner has 98

- Partner has the nine and dummy has HJ

 

Furthermore, we're expecting partner to have about 7/32 of the outstanding high-card strength. The probability has to be reduced to reflect that expectation.

 

I'd guess that the actual chance of picking up partner's queen is in the 2-3% range.

 

But it can also pick up his king, or turn KJx, AJx, KQx and AQx into one trick.

[gnasher]

But it can also pick up his king, or turn KJx, AJx, KQx and AQx into one trick.

 

I intended AQx and KQx to be included in my 2-3%, but anyway I agree that these are all reasons not to lead a trump. I was just nitpicking Jinksy's calculation, rather than actually advocating a trump lead (though it is what I'd lead).

[Jinksy]

3/10 is the probability that partner has any 3-card holding including the queen, given that all we know is that he has three cards. However, that's not the probability of picking up his queen.

 

 

To calculate the actual probability of picking up partner's queen you have to exclude layouts where declarer was going to finesse it anyway, and the layouts where partner's holding is strong enough to survive the lead. That means you have to exclude layouts where:

 

- Declarer has the jack

- Dummy has AKJ

- Partner has the jack

- Partner has the king and there was an intrafinesse

- Partner has 98

- Partner has the nine and dummy has HJ

 

Furthermore, we're expecting partner to have about 7/32 of the outstanding high-card strength. The probability has to be reduced to reflect that expectation.

 

I'd guess that the actual chance of picking up partner's queen is in the 2-3% range.

 

Well sure, but by 'picking up' I mean 'effectively solving for declarer on the lead', not doing something he couldn't theoretically do himself. In many such situations his options for playing the hand will then then give him fewer opportunities to go wrong elsewhere. If we knew the actual probabilities of it giving something away and of (say) a small diamond doing the same, we wouldn't have a lead problem.

[Jinksy]

Maybe even first choice, if you held the card.

 

There's an important space in the the_clown's sentence that you haven't credited him with.

[Thiros]

I led ♠4. E-W have not bid as though their hands can make 4NT. It is unlikely that declarer's play plan will involve drawing trumps early. Note that this is not a domineering consideration but tips the balance only in light of the fact that leading from the other holdings is relatively unappealing. Change the hearts to ♥QJ10 and I am a heart leader (I think). Leading the ♠10 would be easier on partner but I see tangible benefit in retaining the ♠10 here. Suppose there is four of a red suit in dummy and two of that suit in declarer's hand; if he tries for two ruffs of that suit in his hand, our ♠10 may create a complication for the offense when dummy leads the fourth round.

[nige1]

[hv=pc=n&s=st4hk83dj43cat843&d=e&v=b&b=10&a=1np2cp2sp3sp4sppp]133|200|

 

IMP all red

5 different cards chosen by panelists,

close to even 4 way split among both panelists and solvers for the top lead.[/hv]

I rank

 

1. ♠ Passive. John Mclaren called trumps "The Idiot's lead". Lead the ten not the four.
2. ♥ Aggressive. Might set up a trick before loser cab be discarded on dummy's club.
3. ♦ Wishy-washy. Usually passive but might set up a trick.
4. ♣ The sight of dummy may suggest something

[cherdano]

I really dislike the heart lead given that declarer denied length in the suit. Lead from the king is most dangerous when declarer has a doubleton, and the odds of that have gone up quite a bit when he denied a 4-card heart suit.

[mike777]

I really dislike the heart lead given that declarer denied length in the suit. Lead from the king is most dangerous when declarer has a doubleton, and the odds of that have gone up quite a bit when he denied a 4-card heart suit.

 

interesting

 

I would have lead a h, aggressive as a nonexpert....ty for post.

[PhilKing]

These days, the very top players virtually never lead away from a king on an auction like this.

 

The lead of a heart might score OK in the Bridge World, but that is because although times have changed, the panel contains a lot of octogenarians who are used to a far more aggressive style of leads.

[Zelandakh]

The heart suit is what I would lead....I would lead low.

 

The lead of a heart might score OK in the Bridge World, but that is because although times have changed, the panel contains a lot of octogenarians who are used to a far more aggressive style of leads.

Ouch! :blink: For what it is worth I was also surprised Mike went for the heart.

[PhilKing]

Ouch! :blink: For what it is worth I was also surprised Mike went for the heart.

 

I'll get my coat.

[mikeh]

These days, the very top players virtually never lead away from a king on an auction like this.

 

The lead of a heart might score OK in the Bridge World, but that is because although times have changed, the panel contains a lot of octogenarians who are used to a far more aggressive style of leads.

Well, it isn't as tho we have a purely passive lead on the hand. Had my spades been even a tad worse, I would have led one in a heartbeat. Were my diamonds lacking the J, that would have been an easy choice as well. IMO, all of the lead options were dangerous, which is presumably why it was seen as a good problem. The fact that 'the very top players virtually never lead away from a king' on this type of auction doesn't impress me very much, because on virtually all auctions like this, we will have at least one lead that seems far safer than leading away from the king. Fwiw, I would not lead from the king here if I held 4 or more in the suit, since that would slightly increase the chances of the most dangerous declarer holding...a doubleton with his side holding the A and the Q. I think I'd lead a spade then.

 

So, while I am not even close to being one of the very top players, I would 'virtually never lead away from a king on this auction' either :P it's merely that when all leads are bad, this time the heart seems to me to be the best of a bad bunch.

[aguahombre]

Maybe even first choice, if you held the card.

He meant "A" as an article, not Ace.... a low heart.

[Mbodell]

For some results, here was how the panel in MSC voted/rated:

 

Action  Score  Panel Votes  % of Solvers
S4       100       9              23
ST        80       6              24
D3        80       7              25
H3        60       4              19
C3        40       1               2
CA        20       0               3
other      0       0               4

 

At the time of this posts the bbf voting is scattered with multiple votes for both spades, diamond 3, and club A and single votes for others.

 

Based on my simulation (code here, you can check my assumptions on this auction restrictions) I got this result for simulation (imp score is compared to the ♣A lead):

 

ST lead yeilds 101528 tricks (10.1528), sets 2456 times (24.56%) with imps of -4963 (-0.4963).

S4 lead yeilds 101519 tricks (10.1519), sets 2461 times (24.61%) with imps of -4899 (-0.4899).

HK lead yeilds 103731 tricks (10.3731), sets 1934 times (19.34%) with imps of -13168 (-1.3168).

H8 lead yeilds 101785 tricks (10.1785), sets 2378 times (23.78%) with imps of -5991 (-0.5991).

H3 lead yeilds 101769 tricks (10.1769), sets 2388 times (23.88%) with imps of -5869 (-0.5869).

DJ lead yeilds 101784 tricks (10.1784), sets 2469 times (24.69%) with imps of -4909 (-0.4909).

D4 lead yeilds 101192 tricks (10.1192), sets 2671 times (26.71%) with imps of -2073 (-0.2073).

D3 lead yeilds 101192 tricks (10.1192), sets 2671 times (26.71%) with imps of -2073 (-0.2073).

CA lead yeilds 100077 tricks (10.0077), sets 2756 times (27.56%) with imps of 0 (0.0).

CT lead yeilds 103017 tricks (10.3017), sets 2186 times (21.86%) with imps of -9173 (-0.9173).

C8 lead yeilds 102777 tricks (10.2777), sets 2274 times (22.74%) with imps of -7936 (-0.7936).

C4 lead yeilds 102680 tricks (10.268), sets 2302 times (23.02%) with imps of -7533 (-0.7533).

C3 lead yeilds 102680 tricks (10.268), sets 2302 times (23.02%) with imps of -7533 (-0.7533).

 

That is, the DD best lead is the ♣A (unsurprisingly since DD favors the A always knowing the exact right continuation). The second best choice was the ♦3/4. Leading a trump was about as good as leading the ♦J, and both were better than a heart or low club. The really horrible lead was the ♥K, and the ♣T was also pretty bad.

 

I added the "second best choice" to the version of the MSC poll I did last month, partially because I knew the A was going to be the DD favorite this month, and wanted to do the "second best choice" this month without making that 100% obvious that the A was going to be DD best. I'm still trying to figure out how to sim next months MSC, since the auction is very messy, and much of the problem's purpose, I think, is to figure out what people think the various sequence means.

[mikeh]

For some results, here was how the panel in MSC voted/rated:

 

 

 

At the time of this posts the bbf voting is scattered with multiple votes for both spades, diamond 3, and club A and single votes for others.

 

Based on my simulation (code here, you can check my assumptions on this auction restrictions) I got this result for simulation (imp score is compared to the ♣A lead):

 

 

 

That is, the DD best lead is the ♣A (unsurprisingly since DD favors the A always knowing the exact right continuation). The second best choice was the ♦3/4. Leading a trump was about as good as leading the ♦J, and both were better than a heart or low club. The really horrible lead was the ♥K, and the ♣T was also pretty bad.

 

I added the "second best choice" to the version of the MSC poll I did last month, partially because I knew the A was going to be the DD favorite this month, and wanted to do the "second best choice" this month without making that 100% obvious that the A was going to be DD best. I'm still trying to figure out how to sim next months MSC, since the auction is very messy, and much of the problem's purpose, I think, is to figure out what people think the various sequence means.

I suspect that I misread your code, which wouldn't surprise me at all. However, maybe you can clarify the shape constraints you imposed on the 1NT opening bid. FWIW, I would have limited the hand to 4 spades, 2-3 hearts, and 2-4 in each minor, plus (if I could include this) any 5332 with 5 spades, and of course opener is to have 16-17 hcp.

 

I am not at all sure what your constraints were, but what info I was able to discern causes me to think there may be a problem. I doubt, for example, that many good players would hold 4=2=2=5 shape for 1NT, so if your sim allows that, then IMO the results will be skewed, and the same is true if you allow 4 hearts for opener and so on. I see you ruled out that latter hand, but you had responder using stayman with 7 hcp, and inviting, and I don't think that would be popular.

 

Edit: double dummy analysis would, I think, distort reality. Consider dummy holding AJxx or KJxx and partner Qxx in trump. Declarer would almost surely lose a trump trick in real life, unless we led a trump, but playing double dummy would lead the J through partner. Thus your sim over-states the effectiveness of the spade lead by assuming that it doesn't blow the suit ever. Similar issues may impact other choices, but certainly this issue really weakens the value of the sim, IMO.

[Mbodell]

I suspect that I misread your code, which wouldn't surprise me at all. However, maybe you can clarify the shape constraints you imposed on the 1NT opening bid. FWIW, I would have limited the hand to 4 spades, 2-3 hearts, and 2-4 in each minor, plus (if I could include this) any 5332 with 5 spades, and of course opener is to have 16-17 hcp.

 

I am not at all sure what your constraints were, but what info I was able to discern causes me to think there may be a problem. I doubt, for example, that many good players would hold 4=2=2=5 shape for 1NT, so if your sim allows that, then IMO the results will be skewed, and the same is true if you allow 4 hearts for opener and so on. I see you ruled out that latter hand, but you had responder using stayman with 7 hcp, and inviting, and I don't think that would be popular.

 

Edit: double dummy analysis would, I think, distort reality. Consider dummy holding AJxx or KJxx and partner Qxx in trump. Declarer would almost surely lose a trump trick in real life, unless we led a trump, but playing double dummy would lead the J through partner. Thus your sim over-states the effectiveness of the spade lead by assuming that it doesn't blow the suit ever. Similar issues may impact other choices, but certainly this issue really weakens the value of the sim, IMO.

 

I generally assume that 4333, 4432, 5332 (including 5M), 5m422 (I.e., not when the 5 is a major), and 6m322 are all possible 1nt shapes (before the rest of the auction comes about). If it is 5M332 and a max, (17 hcp), then I disallow it assuming players would open 1M and upgrade. It is true that not everyone opens all these shapes (In my experience I think the frequency is open 1nt on 5M332 > 5m422 > 6m332 > 5M422 > 5431 > 4441. I didn't include the last 3 at all, but did include the first 3.) Obviously, for many folks it depends on the quality of the suits and fragments as well. I admit I'm biased a bit to include the hands I'd open on (which include nearly all the 5m422 hands as well as the majority of the 6m322 hands) because I sometimes sim auctions I was in. Of course on this auction when we bid 2♠, we have 4 or 5 spades, so the 6m322 can't happen, but 4=2=2=5 and 4=2=5=2 can happen. 5=3=3=2, 5=3=2=3, 5=2=3=3, 4=3=3=3, 4=3=4=2, 4=3=2=4. 4=2=5=2, 4=2=2=5, 4=2=4=3, 4=2=3=4 are the 1nt shapes possible given the auction here (not 4=4=3=2 or 4=4=2=3 because I assumed BWS of 2♥ with both majors). In terms of HCP, with the last 7 shapes opener has 16-17. With the 5(332) opener has 15 or 16 (I assumed 17 would have opened 1♠ and that even with only 15, you'd accept with 5 card spades - double dummy you certainly should opposite my invite range below - even with the invite occasionally having 7 hcp).

 

For the 7 point hands, I only had those if you had 4 hearts and 5 spades and 7 points for the invite opposite 1nt (I agree not everyone would do that, but some would be able to try to improve the part score and upgrade to the invite when they hit the 9+ card trump fit). For the 8 hcp invites I had you accept any time you had 4+ spades (and a shape that uses stayman) except exactly 4=3=3=3. Invites also include 9 hcp hands, but not 10 (since 10 would game force).

 

I would invite anyone else to use the assumptions that make sense to them, I expect the DD results will be fairly similar in their ordering of the leads, but perhaps not. It is true that DD gets certain things wrong about guessable suits and the like. I don't think this hand is especially bad for DD analysis, though.

[mikeh]

I generally assume that 4333, 4432, 5332 (including 5M), 5m422 (I.e., not when the 5 is a major), and 6m322 are all possible 1nt shapes (before the rest of the auction comes about). If it is 5M332 and a max, (17 hcp), then I disallow it assuming players would open 1M and upgrade. It is true that not everyone opens all these shapes (In my experience I think the frequency is open 1nt on 5M332 > 5m422 > 6m332 > 5M422 > 5431 > 4441. I didn't include the last 3 at all, but did include the first 3.) Obviously, for many folks it depends on the quality of the suits and fragments as well. I admit I'm biased a bit to include the hands I'd open on (which include nearly all the 5m422 hands as well as the majority of the 6m322 hands) because I sometimes sim auctions I was in. Of course on this auction when we bid 2♠, we have 4 or 5 spades, so the 6m322 can't happen, but 4=2=2=5 and 4=2=5=2 can happen. 5=3=3=2, 5=3=2=3, 5=2=3=3, 4=3=3=3, 4=3=4=2, 4=3=2=4. 4=2=5=2, 4=2=2=5, 4=2=4=3, 4=2=3=4 are the 1nt shapes possible given the auction here (not 4=4=3=2 or 4=4=2=3 because I assumed BWS of 2♥ with both majors). In terms of HCP, with the last 7 shapes opener has 16-17. With the 5(332) opener has 15 or 16 (I assumed 17 would have opened 1♠ and that even with only 15, you'd accept with 5 card spades - double dummy you certainly should opposite my invite range below - even with the invite occasionally having 7 hcp).

 

For the 7 point hands, I only had those if you had 4 hearts and 5 spades and 7 points for the invite opposite 1nt (I agree not everyone would do that, but some would be able to try to improve the part score and upgrade to the invite when they hit the 9+ card trump fit). For the 8 hcp invites I had you accept any time you had 4+ spades (and a shape that uses stayman) except exactly 4=3=3=3. Invites also include 9 hcp hands, but not 10 (since 10 would game force).

 

I would invite anyone else to use the assumptions that make sense to them, I expect the DD results will be fairly similar in their ordering of the leads, but perhaps not. It is true that DD gets certain things wrong about guessable suits and the like. I don't think this hand is especially bad for DD analysis, though.

You and I definitely differ on 5422 hands that have no rebid problem. I think it to be bad bridge to open 1N with such hands, especially at imps where 5m (not to mention minor suit slams or moysian major suit games) are to be preferred over failing 3N contracts. Also, when your sim assumes that the spade lead will virtually never blow a trick, because declarer will always play us for 10x whatever suit we lead, and the results of all non heart K leads are within a couple of percentage points, then you have lost me completely. The implications of double dummy play must have at least a few percentage point implications, thus rendering the results you obtained basically meaningless IMO. This is not an attempt to salvage respect for my choice of leads, btw :D I have long viewed double dummy analysis as seriously flawed as a means of assessing this sort of problem.