[benlessard]

Quote

Are you saying that if I lead a card that shows a four-card heart suit, opener will play me for short clubs?

Not necessarely play you for short club but he will finesse partner more often then is going to finesse you.
1- If your lead may suggest a 5+ card suit
2- If they got 7H.
3- Its more likely that he will want to keep RHO off lead then LHO.
4- if he can get a more complete count of the hand by playing 3 or 4 round of diamonds.

Some entry problem might induce declarer to finesse on your side. But the odds favor that for clubs he will finesse RHO.

[jdonn]

benlessard, on May 27 2008, 09:38 AM, said:

Quote

Do you have anything to back this up?? I totally disagree. It's not just solving a 2 way finesse. Give partner QJxx or something. Or like KT8x where you show declarer how to pick up the suit, or JTxx etc, there are tons of times it gives up a trick. Not to mention the times leading the right other suit would actually set up tricks!

1- Because partner is poor he rate to have no pts in clubs.

2- If hes A or K and no spot it cost nothing. If he got Qxxx then declarer would probably have finesse him anyway (unless i falsecard my H or S lead). If hes got QJxx it cost nothing. (think about it and you will see) If K or Q with a spot it might not cost at all and sometimes declarer will play me for having 4 clubs.

Q9xx---AJ8x partner KTxx is safe anyway.
Q9xx----AK8x partner JTxx is safe.

By far the most likely case where its blow a trick is when Qxx but even with this declarer might still finesse him to keep him off lead.

Not only a club lead is unlikely to cost a trick but when you put thing in context by comparing a club lead VS the other lead its obvious to me that a club lead is very safe and very passive.

Almost every statement in this post is untrue. I don't even want to waste my time arguing.

[skjaeran]

A club lead would never enter my mind. It might turn two tricks with partner in the suit into none, more often one to none. And help declarer with all four suits.

Which of my three suits is the best lead is not so clear though. I'm more inclined to lead a spade than most here - Axxx is a lead I abhor, AJxx is completely different. I think it's very close between the majors here.

[han]

skaeran, on May 27 2008, 12:58 PM, said:

I'm more inclined to lead a spade than most here - Axxx is a lead I abhor, AJxx is completely different. I think it's very close between the majors here.

I'm glad you say so. The double dummy simulation clearly makes the club lead look better than it is. But I see no reason why it should make the spade lead look better than a heart lead if in reality it is the other way around.

Why does almost everybody prefer hearts and if you do prefer hearts, why do you think the simulation incorrectly suggests spades is better?

(you in the last sentence was not meant as Harald but rather the rest)

[benlessard]

Quote

Almost every statement in this post is untrue. I don't even want to waste my time arguing.

Great argument. This really show why your bridge is better then mine.

Anyway this is more mental masturbation then anything because im never leading clubs on that deal. Ill definitively want to make a sim to check if my S lead is better then a H lead.

Quote

  Why does almost everybody prefer hearts

Because they think i want to establish a trick and use the A of S as a side entry. Where i think this reasonnement is a bit off , is that if the K of H is badly placed (and partner doesnt do magic) we are unlikely to put this contract down anyway so might as well assume declarer got the A of H and see our K of H as an entry. So at the end you get Ajxx = more ambitious lead then (A)txx.

[FrancesHinden]

han, on May 27 2008, 07:44 PM, said:

I'm glad you say so. The double dummy simulation clearly makes the club lead look better than it is. But I see no reason why it should make the spade lead look better than a heart lead if in reality it is the other way around.

Why does almost everybody prefer hearts and if you do prefer hearts, why do you think the simulation incorrectly suggests spades is better?

(you in the last sentence was not meant as Harald but rather the rest)

My reaction to the problem was to lead a heart for the traditional 'set the heart suit up and then I have the ace of spades as an entry' line. This is a prime example of the type of hand where the DD analysis of the club lead has much to do with real life, simply because in real life the club lead will pick up partner's club holding on many layouts where declarer would go wrong single dummy*.

I did a 100-hand single-dummy simulation and I now think it is less obvious than above, plus at least I think I understand why a spade comes out better.

I used the following constraints (roughly in line with what you might expect of me to have for a 1NT opening)
- Opener has no singleton and either 15-17 with no 5-card suit, or 14-16 with a 5- or 6-card minor
- responder has 9-12 HCP and either 4333 (any order) or no 4-card major plus no void and at most one singleton.

From this sample, I found that the contract was potentially beatable on 56 hands. On 7 of them it didn't matter what you led. A heart was necessary on 23, a spade on 19, either major worked on 3, a diamond on 3 and a club on precisely one.

('potentially beatable' means either definitely off, or declarer has a play problem which he might well get wrong)

I don't think the difference between the majors is statistically significant, but I do think a heart lead would be better if we didn't have the SJ and the DQ; one of the problems with the heart was that even when it is 'right' e.g. declarer has AJ9 and partner Qxx, we can't get partner in to play a heart through. When a spade is 'right' we don't need a second one played by partner (in fact when spades are our suit we usually need partner to play a heart through).

A major suit lead cost a trick about 60% of the time, with no difference between hearts and spades, and a diamond lead more than that (that 9 of diamonds is a valuable card if you don't lead away from the Q9) and anyway oppo have more diamonds between them.

If responder has 13+ HCP then a spade is by far the best lead as about the only way to beat the contract is to cash the first five spade tricks. That's why DD a spade wins over the space of all possible hands. If they had an invitational sequence I believe a spade lead will get relatively worse.

One prejudice I have that I confirmed is that a passive lead is definitely wrong. I found exactly one hand in a 100 (the one where the club lead was right) where the only way to have a hope of beating the contract was not to give a trick away on the lead. I hate passive leads against this auction even at matchpoints.

*it's a side issue, but based on 3 samples of 100 simulated hands a club lead costs a trick in the suit 25% of the time compared to declarer's normal line.

[han]

FrancesHinden, on May 28 2008, 03:38 AM, said:

*it's a side issue, but based on 3 samples of 100 simulated hands a club lead costs a trick in the suit 25% of the time compared to declarer's normal line.

This is a wonderful comment. Could you elaborate?

[FrancesHinden]

han, on May 28 2008, 09:43 AM, said:

FrancesHinden, on May 28 2008, 03:38 AM, said:

*it's a side issue, but based on 3 samples of 100 simulated hands a club lead costs a trick in the suit 25% of the time compared to declarer's normal line.

This is a wonderful comment. Could you elaborate?

Without looking at whether it was a 'good lead' in terms of beating the contract (as I said, it was hopeless) I was interested in looking to see how passive a club lead actually is. By 'passive' I mean that leading one will make no difference in the number of tricks that declarer would make were he left to play on the suit himself. So on 75% of hands whether or not you lead a club doesn't affect the play in the suit, because either
i) Declarer is solid (AQxx opposite KJxx or whatever), or
ii) Declarer's normal line picks up partner's holding (Kxx in dummy AJ10xx in hand, or AQxx opposite K10xx etc)

On 25% of hands you cost a trick by leading the suit, because you pick up partner's holding, which is either
i) One declarer would never play for (Kx opposite AQJ9x)
ii) One where declarer would not usually play for that layout (e.g. AJ10xx in dummy opposite Kxx in hand, or Qxx opposite AK98x)

There are a few hands which are fuzzy e.g. A98x opposite Q1076 in hand, and I counted about half of these as costing (e.g. if declarer has to play on the suit himself and knows you have led a 4-card suit his choice of who to play for club length will depend on this combined holdings in all the suits).

The club lead actually turned out to be more passive than I had expected because of the combination of our diamond length and responder's lack of major suit length - if we were, say, 5521 or if responder had shown a 4-card major (e.g. 1NT - 2C - 2D - 3NT) I believe - although I haven't checked - that a club lead will cost more often.

I am vaguely interested to know why a club does so well DD, when on my simulation it virtually never beat the contract. Can you extract any of the hands where a club lead was successful and other leads weren't?

[gnasher]

[quote name='Jlall' date='May 27 2008, 05:23 PM'] Are you saying that if I lead a card that shows a four-card heart suit, opener will play me for short clubs? [/QUOTE]
lol [/quote]
You may laugh, but a lot of otherwise sensible people do believe that such a play would be correct, possibly because Hugh Kelsey inexplicably said they should in Bridge Odds for Practical Players.

There is, in fact, some experimental evidence that they're right, but only if I happen to be in the opposing team.

[han]

FrancesHinden, on May 28 2008, 04:13 AM, said:

han, on May 28 2008, 09:43 AM, said:

FrancesHinden, on May 28 2008, 03:38 AM, said:

*it's a side issue, but based on 3 samples of 100 simulated hands a club lead costs a trick in the suit 25% of the time compared to declarer's normal line.

This is a wonderful comment. Could you elaborate?

Without looking at whether it was a 'good lead' in terms of beating the contract (as I said, it was hopeless) I was interested in looking to see how passive a club lead actually is. By 'passive' I mean that leading one will make no difference in the number of tricks that declarer would make were he left to play on the suit himself. So on 75% of hands whether or not you lead a club doesn't affect the play in the suit, because either
i) Declarer is solid (AQxx opposite KJxx or whatever), or
ii) Declarer's normal line picks up partner's holding (Kxx in dummy AJ10xx in hand, or AQxx opposite K10xx etc)

On 25% of hands you cost a trick by leading the suit, because you pick up partner's holding, which is either
i) One declarer would never play for (Kx opposite AQJ9x)
ii) One where declarer would not usually play for that layout (e.g. AJ10xx in dummy opposite Kxx in hand, or Qxx opposite AK98x)

There are a few hands which are fuzzy e.g. A98x opposite Q1076 in hand, and I counted about half of these as costing (e.g. if declarer has to play on the suit himself and knows you have led a 4-card suit his choice of who to play for club length will depend on this combined holdings in all the suits).

The club lead actually turned out to be more passive than I had expected because of the combination of our diamond length and responder's lack of major suit length - if we were, say, 5521 or if responder had shown a 4-card major (e.g. 1NT - 2C - 2D - 3NT) I believe - although I haven't checked - that a club lead will cost more often.

I am vaguely interested to know why a club does so well DD, when on my simulation it virtually never beat the contract. Can you extract any of the hands where a club lead was successful and other leads weren't?

Did you go through the hands manually or were you able to program this?

I didn't keep the hands for my simulation. I don't know if there were any hands where a club was the only lead that would beat the contract. I think that almost always one of the other three suits would just as well. The double dummy analysis assumes that your side finds the right switch later so when the club lead doesn't give up a tempo it is almost always one of the best double dummy leads.

[FrancesHinden]

han, on May 28 2008, 12:08 PM, said:

Did you go through the hands manually or were you able to program this?

Manually

[nige1]

han, on May 24 2008, 08:14 PM, said:

Watching the women trials I heard the theory that AJxx, K10xx or Q9xx are the worst holdings to lead from against NT.

What would you lead with ♠ AJxx ♥ K10xx ♦ Q9xx ♣ x against 1NT-3NT at IMPs?

My double dummy analysis not surprisingly suggest that the small club is best but this seems very suspicious for real life. Apparently the second best double dummy lead is the spade ace followed by a low spade. Hearts is worst (well, the diamond queen is worst ). What would you lead at the table?

han, on May 28 2008, 12:08 PM, said:

Did you go through the hands manually or were you able to program this?

FrancesHinden, on May 28 2008, 06:09 AM, said:

Manually

We are grateful to both Han and Frances for taking the trouble to perform their simulations. Assuming representative samples, it is an eye-opener to learn how significantly different the analysis results are when comparing double-dummy with single-dummy.

In the case of a ♣ lead, perhaps, on reflection, the difference is not quite so surprising. Like most BBOers, however, I would lead a ♥; never a minor.

Unless opponents are stretching, Frances' explanation of the case for a ♠ lead is pretty convincing.

Han's conclusions seem counter-intuitive so Frances' post came as a relief; but each simulation is instructive in its own way. Thanks again, both of you.

[han]

I didn't post conclusions.

[nige1]

han, on May 29 2008, 01:32 AM, said:

I didn't post conclusions.

Sorry Han, I meant the result of your simulation.

[han]

Ah ok, no problem of course.

I won't be able to run simulations for the next month or so but I hope to get back to this topic and compare for example AJxx with Axxx and K10xx with Kxxx.

[benlessard]

Ive only done manually 52 deal so far wich is not enough to post any numbers and barely enought to make speculations. What im getting is similar to Frances. My specualtions are a club and diamond seldom work. H and S are about the same. M and D often blow a trick. In My 50 deal sample a C lead blow a trick only once wich is why lower then i would expect. The distribution of clubs look like
2=2
3= 8
4= 17
5=11
6 =12
7=2

So my gut feeling is that in MP leading the stiff clubs is the best lead by a mile.

The condition ive are about the same for declarer excepted that ive accept some of the 17 with 5 card suit hands.
For dummy ive put 7pts & + with 4M possible and rejected a lot of hand where 7-8 hcp isnt enough (but keept all the AKxxxx) and discarded everyhand where i would go throught stayman. I was Imps agressive the worst hand ive blasted to game was Q9x,QJx,xx, KTxxx. (and 3 nt has no play at all on any lead)

In restrospect ive should have put a limit to north hand because im getting too many hands where 3nt is cold. So my sample where a specific M lead is necessary to beat the contract is way to small to check wich M will turn out best.

Can we put lin files of many deals on the forum ? if yes what is the limit on the numbers of deals ?

[Cascade]

Some single dummy data of 4-card suit leads versus 1NT 3NT.

These data were obtained by GIB playing hands single dummy.

Each line of data represents 100* hands played in which the given honour combination occurred.

* Some lines show more than 100 because for example when I generated 100 hands with QJTx twice there were two suits in the same hand with the identical honour combination.

IMPs won is calculated based on a cross-IMPs. For each hand I made the "standard" lead from each of the four suits and cross-IMPed the results - no average (I think they use the same sort of scoring in the Cavendish but on BBO they average the cross-IMPs).

100 is really quite a small sample but you get a feel for the ranking of various leads.

I did not distinguish 9s so I have no explicit data on Q9xx etc they are lost within Qxxx - actually if I could be bothered I could extract the data for Q9xx compared with Q8xx etc but these would be even smaller samples.

I also have data for all 1, 2, 3 and 5-card honour combinations. e.g. a small singleton in the simulation lost on average 1.22 IMPs per deal.

Also not recorded here the simulation showed that there was a large premium on leading a major rather than a minor on the given auction. Possibly this was over estimated as I excluded some 4-3-3-3 hands with responder where 'standard' practice might be to not look for the major fit. Nevertheless I am confident as I am sure that you will be that there is a premium on leading a major.

Combination Frequency IMPs Won Mean IMPs SD      rank
AKQx         100       920      9.20     13.74    1
AKQJ         100       616      6.16      7.67    2
KQJT         100       515      5.15     11.67    3
AKQT         100       363      3.63     11.87    4
AKJx         100       337      3.37     14.05    5
KQJx         100       296      2.96      9.47    6
JTxx         106       222      2.09     10.87    7
AKJT         100       197      1.97     12.00    8
QJTx         102       168      1.65      9.76    9
xxxx         105       160      1.52     11.05   10
KQTx         100       130      1.30     12.04   11
QJxx         103       130      1.26     11.49   12
Qxxx         102        98      0.96     11.26   13
Txxx         102        46      0.45      8.10   14
ATxx         100        42      0.42     11.82   15
QTxx         101        41      0.41     11.35   16
Kxxx         103        31      0.30     11.16   17
Jxxx         105        30      0.29      9.36   18
AJxx         100        -9     -0.09     13.44   19
AQTx         101       -49     -0.49     11.65   20
KTxx         101       -59     -0.58     10.57   21
AKTx         100       -66     -0.66     10.69   22
AQJT         100       -71     -0.71     10.77   23
KJxx         100       -96     -0.96     10.26   24
AJTx         100      -120     -1.20     12.00   25
KQxx         103      -124     -1.20     10.64   26
Axxx         100      -121     -1.21     10.13   27
KJTx         100      -144     -1.44     13.12   28
AKxx         100      -144     -1.44     11.98   28
AQxx         100      -176     -1.76     11.38   30
AQJx         100      -288     -2.88     13.59   31

[jtfanclub]

Cascade, on May 29 2008, 03:43 PM, said:

KQxx         103      -124     -1.20     10.64   26
Axxx         100      -121     -1.21     10.13   27
KJTx         100      -144     -1.44     13.12   28
AKxx         100      -144     -1.44     11.98   28
AQxx         100      -176     -1.76     11.38   30
AQJx         100      -288     -2.88     13.59   31

I'm curious, if you don't mind, how the bottom 6 did with the opposite-from-standard lead. For example, if the standard lead from AKxx is the king, how did it do if you led low?

[jdonn]

Interesting that AKQx fares so much better than AKQJ. Partner has five cards in the suit that often??

Now that I look more, how could AKQT fare so much worse than both AKQx and AKQJ? That makes no sense at all, I think something here is flawed.