[JLOGIC]

xx KQT7x Qxxx xx playing imps

1N p 3N all pass.

Basically I'm curious what is the cutoff point where we stop leading the HK. Or do we always lead it, even without the DQ? Obviously it wins on AJ doubleon or Ax+Jx when they don't have 9 runners which seems easy enough to quantify. The harder part to quantify is how often we have an essential entry, and how often we can beat it by just being passive. I feel like the DQ with nothing else is a pretty good cutoff, with a king or even some stray jacks I would feel good about the HK lead, and with just a jack or nothing I would feel fine about leading a low heart but this one felt tough.

[MrAce]

JLOGIC, on 2011-June-11, 19:11, said:

xx KQT7x Qxxx xx playing imps

1N p 3N all pass.

Basically I'm curious what is the cutoff point where we stop leading the HK. Or do we always lead it, even without the DQ?

I would not lead K (or Q if thats our method) with or without the ♦Q but nothing else. I think the way you summarized the cut off point pretty much says it all.

[Hanoi5]

This is one of those topics which come up very seldom and which really belong to this board.

I would always lead the K from KQTxx. I would have thought about not losing to a singleton or doubleton J, never about entries as when leading from AKxxx.

You read, you learn...

*sits and waits for people-who-know to answer the question*

[JLOGIC]

Not sure if it will help generate any discussion but at the table I led low but wasn't sure, so I asked my partner Han to simulate it. In 400 boards of double dummy, the HK beat it 81 times and low beat it 65 times. Dummy was not allowed to have 4 hearts or a stiff heart (though perhaps 4333 with a 4 card major should have been included, and I'm not sure how it would alter the results, and maybe some hands with stiff J of hearts would bid 3N but I'm not sure how to quantify it). My partner had Axx of hearts irl so it didnt matter.

This type of hand is common enough that maybe it's worth investing some time doing some work simulating stuff and also trying to simulate single dummy to see whether double dummy favors one or the other. Another one that's seemed to pop up a lot recently is QJTxx and an ace. In that case I feel pretty confident low is right though so I won't even bother with simulating (or rather, having han simulate!).

[kgr]

It would be interesting for me if you could explain why leading low is getting better when you don't have side entries. (eg with KQ98x when you only have ♦A). Is it because partner needs to have a good card in ♥ anyway?
-
Analyzing with Jack for 1000 deals:
With ♥KQT7x:
- With ♦Q:
♥K: -312.5
♥x: -364.7
- Low ♦ iso ♦Q:
♥K: -324.8
♥x: -369.4
- ♦A iso ♦Q:
♥K: -217.6
♥x: -292.0
- - - -
With ♥KQ982:
- and ♦A:
♥x: -282.1
♥K: -287.2
- and ♣Q & ♦A:
♥K: -299.7
♥x: -300.7
- and ♣K & ♦A:
♥K: -213.2
♥x: -231.7
- - - -
With ♥QJT32:
- and ♦Q:
♥Q: -349.6
♥2: -400.7
- and ♦A iso Q:
♥Q: -270.8
♥2: -327.8
- and ♦x iso Q:
♥Q: -352.1
♥2: -404.6

[bluecalm]

Here you go:
First, let's assume 3NT bidder has 9-14hcp without singleton major or 4+ card major unless he is 4-3-3-3 or his major singleton is at least a Q.
All the hands are simulated on 1000 hands sample. Numbers listed are numbers of times given lead defeats 3NT.

1)Your hand:
8♠ - 114
K♥ - 213
3/7♥ - 162
3♦ - 89
2♣ - 105

2)85 KQT73 8743 52

8♠ - 123
K♥ - 182
3/7♥ - 161
3♦ - 94
2♣ - 87

Which should end the discussion about side entries in double dummy play.
I went through simulated hands to see why K♥ is better than a low one without side entry:
a)K better:
1)they had J5 to A98 and after cashing two hearts we switch to establish more tricks while low heart gives away both trick and a tempo x2
2)partner had xxxx of hearts and decl Ax to Jx (AJ second in one hand) x2
3)AJ second in dummy; xxx in partner's hand
4)Ax in dummy, Jxx in declarer's hand; if he wins, partner will play heart through if he doesn't we just establish hearts x2
5)Jx 2n in dummy, Axxx in declarer's hand; he needs to duck once and then we have a chance to find a killing switch x2
6)similar to 5) but AJx in declarer's hand
7)they had hearts xxx to AJ8x but still they don't have 9 tricks after Kh, low gives 9th one

b)low better:
1)partner has Ax of hearts x4

Those are from hands when it mattered (from 250 hand sample; I didn't have a patience to go through all 1000).
It seems that the only gain of leading low is hoping for Ax in partner's hand while there are numerous ways Kh could be better than the low one.

[bluecalm]

Hmm, it seem that Jack's simuls gives different results than double dummy simuls. Any idea why it should be the case ? How good is Jack in defence, signalling etc ? Or maybe you gave numbers of how often 3NT makes instead of how often it fails because the results seems to reversed of what I would except.

[bluecalm]

Quote

QJTxx and an ace. In that case I feel pretty confident low is right though so I won't even bother with simulating (or rather, having han simulate!).

Hmmm ?
97 QJT54 A65 765

7♠ - 120
Q♥ - 219
5♥ - 203
A♦ - 89
x♦ - 81
x♣ 107

Why it matters:
a)high h is better:
1)they have A9 to K8xx and not enough tricks on the side
2)K9x in dummy, Axx in partner's hand x2
3)They have 9x to AK8 or AK9 to xx x2
4)They haev AK97 to xxx in hearts but not enough tricks on the side

b)low h is better
1)partner has Kx and they have A9xx in one hand (Ax to K9xx) x6
2)K9 in partner's hand, they have Axxx

Admittedly it's very close.
If we substitute T with a 9 still Q wins slightly.
If we substitute T with an 8 then low is already better.

[kgr]

bluecalm, on 2011-June-12, 03:14, said:

Hmm, it seem that Jack's simuls gives different results than double dummy simuls. Any idea why it should be the case ? How good is Jack in defence, signalling etc ? Or maybe you gave numbers of how often 3NT makes instead of how often it fails because the results seems to reversed of what I would except.

Jack gives the expected score...all negative numbers.

[bluecalm]

Quote

Jack gives the expected score...all negative numbers.

Could you elaborate on it ? expected score comparing to what and for which side ?
What those numbers mean ?

[kgr]

bluecalm, on 2011-June-12, 04:24, said:

Could you elaborate on it ? expected score comparing to what and for which side ?
What those numbers mean ?

Expected IMP score.
-600
+100
+200
=> -300/3 = -100
I thought I did set no-one Vulnerable. So it is strange that expected score for last analyses is -404.6.
Maybe I did set everyone vulnerable.

[bluecalm]

I see, thanks, so Jack analysis gives similar results to my double dummy analysis afterall.

[cherdano]

JLOGIC, on 2011-June-11, 19:11, said:

xx KQT7x Qxxx xx playing imps

1N p 3N all pass.

Basically I'm curious what is the cutoff point where we stop leading the HK. Or do we always lead it, even without the DQ? Obviously it wins on AJ doubleon or Ax+Jx when they don't have 9 runners which seems easy enough to quantify. The harder part to quantify is how often we have an essential entry, and how often we can beat it by just being passive. I feel like the DQ with nothing else is a pretty good cutoff, with a king or even some stray jacks I would feel good about the HK lead, and with just a jack or nothing I would feel fine about leading a low heart but this one felt tough.

I feel like you aren't giving the ♥K lead enough credit. Sometimes hearts are Jx - Axx in the opponent's hands, and taking two heart tricks and switching is enough to beat the contract. Sometimes declarer won't know hearts are 5-3.
Meanwhile a low heart only gains when partner has Ax and dummy Jxx, or declarer Jx or Jxxx, and of course the cases where partner has Jx, hearts split 4-2, and we have an entry.

[FrancesHinden]

JLOGIC, on 2011-June-12, 02:11, said:

Not sure if it will help generate any discussion but at the table I led low but wasn't sure, so I asked my partner Han to simulate it. In 400 boards of double dummy, the HK beat it 81 times and low beat it 65 times. Dummy was not allowed to have 4 hearts or a stiff heart (though perhaps 4333 with a 4 card major should have been included, and I'm not sure how it would alter the results, and maybe some hands with stiff J of hearts would bid 3N but I'm not sure how to quantify it). My partner had Axx of hearts irl so it didnt matter.

This type of hand is common enough that maybe it's worth investing some time doing some work simulating stuff and also trying to simulate single dummy to see whether double dummy favors one or the other. Another one that's seemed to pop up a lot recently is QJTxx and an ace. In that case I feel pretty confident low is right though so I won't even bother with simulating (or rather, having han simulate!).

I'm slightly surprised by this, it seems far from obvious to me that QJ10xx and an ace should lead a low one. The suit matters: if it's a major, then while declarer can have 4 it's much less likely that dummy has 4 and it's a layout such as A9xx in dummy and Kx in partner where a low one wins (or even A8xx in dummy and 9x with partner). What's more, double dummy analysis is not going to help you here - surely a fairly typical layout where the queen is right is when the declarer is 3-2 with the AK, and has to guess which entry to knock out first; double dummy he knows to play on your side ace and this will not come as a 'win' for leading the Queen, when it ought to be, say, a 50% win.

[FrancesHinden]

...and on a slightly different point, there's been a move recently towards leading honours from suits such as KQ9xx and possible KQ8xx rather than a low one. This goes against leading a low one from KQ107x.

On a related subject, we've recently been discussing the merits of strong 10 leads. These can be a disaster when e.g. dummy has AKx and declarer Jxx; they work well in other situations, notably when dummy is short in the suit - partner leads a strong 10, dummy has singleton Queen, you know to put the king on from Kxxx, but if partner leads the 10 that could be from 1098x or from A109xx you don't know what to do. We reckon that possibly you should play strong 10s when dummy is know to have fewer than e.g. 12 HCP OR a shortage in the suit, and not play them in other positions. Or (and this goes back to the start of this topic) you should carry on playing them, but lead low from say KJ10xx more often.

[bluecalm]

I always though that "classical way" is to lead an honor if you have a nine, use your judgement when you have an eight and lead low when you have something smaller. I am yet to find anything to convince me it's not right.

[Zelandakh]

Blue's sims seem to suggest that the bridge masters of the 40s and 50s might not have been so bad after all. It would be nice to try to categorise times when the traditional standard leads really are wrong.

[bluecalm]

Quote

. It would be nice to try to categorise times when the traditional standard leads really are wrong.

I have noticed that especially American players lead too aggressively. I even remember that Lawrence in one his books wrote that leading from xxx is usually terrible preferring active leads from honors. This is wrong and modern players lead more passively, especially ones from Europe.
There is probably also some space vs leading vs NT contracts for leads from short suits instead classical 4th best, especially if your 4card suit is minor.
Those are difficult to assess though because even if leading low 6 ♥ from Q42 63 K942 9532 might be the best double dummy it will often make the subsequent defense more difficult.
One more example in defense is playing to force the declarer classically thought as the most effective defense but not having that much significance in practice.
For example from A7 8765 54 KT854 and 1NT opener on your right it's right to lead 5♦ or A♠ after both stayman and transfer auctions "classical" advice is to lead low club trying to establish your own suit and force opponents (trump lead is close 3rd and club is clearly the worst choice).
Moving A♠ to ♥ doesn't change anything.

[bluecalm]

Quote

On a related subject, we've recently been discussing the merits of strong 10 leads. These can be a disaster when e.g. dummy has AKx and declarer Jxx; they work well in other situations, notably when dummy is short in the suit - partner leads a strong 10, dummy has singleton Queen, you know to put the king on from Kxxx, but if partner leads the 10 that could be from 1098x or from A109xx you don't know what to do. We reckon that possibly you should play strong 10s when dummy is know to have fewer than e.g. 12 HCP OR a shortage in the suit, and not play them in other positions. Or (and this goes back to the start of this topic) you should carry on playing them, but lead low from say KJ10xx more often.

I think polish leads are superior to standard and solve also those problems (as well as many others).
Those are:
A = AK
K = KQ
Q = QJ or AQJ
J = HJTx or JTx
T = Tx or HT9x
9 = T9+
2nd from xxx+ and Hxx, 4th from Hxxx+ and low from xx (including 9x but not Hx)

I am yet to see one hand where playing "strong ten" is superior to those but the ones when it helps declarer are plentiful (cause imo you really want to play J from HJTx and JTx)

[whereagles]

If you're playing MPs you'd lead the king pretty much all of the time. Imps is another story.

The sim seems to point at the theoretical K lead.