Distribution problem (2/1)

[aguahombre]

And do you have the same feeling about playing 4S in the 6-1 fit, when partner cannot use NMF and then bid his 6-card spade suit without showing serious slam interest?

Probably the answer to my question is that one's entire bidding structure affects whether rebidding 1NT with 1-4-5-3 is a good idea. Being a bit stodgy, I am not willing to change everything to allow for that--so will continue to show 2 or 3 spades with the 1NT rebid.

[fred]

And do you have the same feeling about playing 4S in the 6-1 fit, when partner cannot use NMF and then bid his 6-card spade suit without showing serious slam interest?

Well if the methods I played over 1NT rebids were unable to reveal the singleton spade, it *might* make a difference, but I doubt it.

 

Remember those 30 to 1 odds, that 4S on a 6-1 fit might be the right spot, that good judgment might get you to 3NT on some hands with 6 spades (which will not infrequently be the best spot even if you have a 6-2 or 6-3 fit), and that similar questions could be asked about other approaches.

 

For example, if you rebid 2C (which I can understand) does your system ensure that you can never get to 5C or 6C on a 4-3 fit (to say nothing of the other bad things that might happen)?

 

As far as rebidding 2D is concerned, I am not even going to go there.

 

Fred Gitelman

Bridge Base Inc.

www.bridgebase.com

[aguahombre]

For example, if you rebid 2C (which I can understand) does your system ensure that you can never get to 5C or 6C on a 4-3 fit (to say nothing of the other bad things that might happen)?

 

Yes it (system) does, but unfortunately it doesn't ensure against a silly club contract at the two or three level on occasion :P

[fred]

For example, if you rebid 2C (which I can understand) does your system ensure that you can never get to 5C or 6C on a 4-3 fit (to say nothing of the other bad things that might happen)?

 

Yes it (system) does, but unfortunately it doesn't ensure against a silly club contract at the two or three level on occasion :P

If you and your partner are smart enough to handle that then I strongly suggest you spend some time thinking about improving the way you play NMF (which is much more important even if you never rebid 1NT with a singleton and probably much easier than whatever you are doing to keep out of your 4-3 club fits).

 

If you play the popular (and good IMO) variation of NMF where 2C forces 2D for invitational hands and 2D is a game force, there are a lot of sequences with no obvious meaning that may well be idle in your system. If you use responder's 2NT rebid as artificial as well, then you have even more scope for doing some sexy things.

 

Fred Gitelman

Bridge Base Inc.

www.bridgebase.com

[Jlall]

Fred, do you like rebidding 1N with 1453 and 2C with 1444? Personally I like 1N with 1444 also for much the same reasons (finding hearts, playing 1N, avoiding silly partials).

 

In fact if it was just a partscore hand I would expect 2C to be worse on 1453 than 1444 because we are more likely to get to a 6 card fit (partner frequently bidding 2D with 2D, not as frequently passing 2C with 3 clubs).

 

I guess on other deals I would rather have 4 clubs for my 2C bid though (like if partner bids 4th suit forcing and I bid 3H 1444 seems like a much better shape to have than 1453).

 

Also I like raising sometimes with a small doubleton and 3 trumps.

 

All of this means that for me the chance of having a singleton spade on 1D-1S-1N is not insignificant, though still not that likely at all.

 

I will bid 2S on that auction on the "obvious" hands with 5 spades, I gave an example in another thread of KQT9x xx Qxx xxx I think. That hand will play better in the 5-1 anyways most likely. But a large majority of the time I will pass. I get the impression that Meckwell (who never bid 1N with a stiff and never raise wtih 3) go back to 2S like 90 % of the time that they have 5 spades and a weak hand. Is that closer to your style?

[fred]

Fred, do you like rebidding 1N with 1453 and 2C with 1444? Personally I like 1N with 1444 also for much the same reasons (finding hearts, playing 1N, avoiding silly partials).

 

In fact if it was just a partscore hand I would expect 2C to be worse on 1453 than 1444 because we are more likely to get to a 6 card fit (partner frequently bidding 2D with 2D, not as frequently passing 2C with 3 clubs).

 

I guess on other deals I would rather have 4 clubs for my 2C bid though (like if partner bids 4th suit forcing and I bid 3H 1444 seems like a much better shape to have than 1453).

 

Also I like raising sometimes with a small doubleton and 3 trumps.

 

All of this means that for me the chance of having a singleton spade on 1D-1S-1N is not insignificant, though still not that likely at all.

 

I will bid 2S on that auction on the "obvious" hands with 5 spades, I gave an example in another thread of KQT9x xx Qxx xxx I think. That hand will play better in the 5-1 anyways most likely. But a large majority of the time I will pass. I get the impression that Meckwell (who never bid 1N with a stiff and never raise wtih 3) go back to 2S like 90 % of the time that they have 5 spades and a weak hand. Is that closer to your style?

I generally believe in playing a system and style does not endplay me into not being able to use my judgment with common hand types. So I will sometimes:

 

- rebid 2C with the pattern we have been discussing (not very often at all)

- rebid 1NT with 1444 (over half the time and increasing in recent years)

- raise with 3-card support (only occasionally, but I would probably do it more except my partner doesn't like this)

 

I must say that I don't remember ever having rebid 2C or 2D with a 5-card suit in recent years, but I suppose I could (barely) imagine a hand with which I might do that. There is nothing really systemic about my attitude toward this and it is possible that I am unreasonably biased against this practice.

 

For sure how often I do these sort of things should have an impact on how often I rebid 2S over 1NT with a 5-card suit. I can't say I am consiously aware of having adjusted my style in this area as my style in other relevant areas has changed, but I like to think that good bridge players are capable of making such adjustments without really thinking about it.

 

I think it is closer to 100% for Meckwell.

 

For me, with 5332 I will usually pass 1NT unless my spades are very strong and the rest of my hand is pretty crappy (like your example hand). That is not so much out of consideration for partner having a singleton spade - the extreme example is KQJ109 and out. Obviously this hand will always take 4 tricks in a spade contract but will take only 1 trick in notrump opposite xx in spades and usually only 2 tricks in notrump opposite xxx in spades.

 

When I think a 5332 hand is close, I will sometimes let my holding in partner's minor be the deciding factor.

 

With non-5332, I would usually bid 2S.

 

I have no idea what the numbers work out to, but I would guess I rebid 2S about 80% of the time.

 

I would be surprised if I ever give the question of whether to Pass 1NT or to bid 2S on some particular hand more than a second or two of thought (and probably I do that thinking before partner even rebids 1NT). These decisions can be pretty random and are not worth losing a lot of sleep over IMO. Just doing what feels right with any given hand makes a lot of sense to me.

 

Fred Gitelman

Bridge Base Inc.

www.bridgebase.com

[eyhung]

Note that the odds of a singleton spade increase once partner responds 1S. I haven't created an odds calculator that can take that into account yet.  :P

Fred, I think I can provide a slightly better simulation. As you may have noticed, I've been playing with scripts that model all the hands, using Thomas Andrews's deal program. The process is not completely robust, but I think the results are still interesting.

 

Parameters:

* South has 12-14 HCP, a 1D opening, at most 5 diamonds, at most 3 clubs, at most 3 spades. [This is robust.]

 

* West does not have an overcall, preempt, or takeout double of 1D. [Not as robust -- may contain hands like 85 T94 75 KQJ943, or hands that might bid Michaels or U2N -- still haven't added support for this yet.]

 

* North has any hand that would respond 1S to 1D, in a Walsh style -- could contain a longer suit if North holds non-game-forcing value. [Robust -- i.e., does not contain hands that are 4-4 in the majors.]

 

* East does not have an overcall, preempt, or takeout double of 1S. [same comment as applied to West's pass.]

 

* No hands where South holds 3 spades are thrown out -- we assume South needs 4 spades to raise. [Robust.]

 

-----------------

 

In 1000 deals that fit these parameters, South has:

 

1 spade 66 times

2 spades 426 times

3 spades 508 times

 

So, with the slightly flawed opponent passing routines, the odds have doubled from 30:1 against to approximately 15:1 against. Eliminating some 3-card holdings would increase the odds even more. Perhaps any 3-card spade holding with a stiff, or any 3-card spade holding containing a high honor and a worthless doubleton on the side? I can program that in.

[jdonn]

Obviously you at least eliminate hands where south has 3 spades and a side singleton.

[eyhung]

Perhaps any 3-card spade holding with a stiff, or any 3-card spade holding containing a high honor and a worthless doubleton on the side?  I can program that in.

Turns out it wasn't so hard to throw this parameter in.

 

Results with no South round-suit singletons or worthless doubletons containing 3 spades to a high honor, 10000 hands dealt:

 

1 spade : 799

2 spades : 4925

3 spades : 4276

 

So, the odds appear to be 11.5 : 1 against.

[Jlall]

Perhaps any 3-card spade holding with a stiff, or any 3-card spade holding containing a high honor and a worthless doubleton on the side?  I can program that in.

Turns out it wasn't so hard to throw this parameter in.

 

Results with no South round-suit singletons or worthless doubletons containing 3 spades to a high honor, 10000 hands dealt:

 

1 spade : 799

2 spades : 4925

3 spades : 4276

 

So, the odds appear to be 11.5 : 1 against.

Can you add in 1444 and see how that changes it?

[eyhung]

Perhaps any 3-card spade holding with a stiff, or any 3-card spade holding containing a high honor and a worthless doubleton on the side?  I can program that in.

Turns out it wasn't so hard to throw this parameter in.

 

Results with no South round-suit singletons or worthless doubletons containing 3 spades to a high honor, 10000 hands dealt:

 

1 spade : 799

2 spades : 4925

3 spades : 4276

 

So, the odds appear to be 11.5 : 1 against.

Can you add in 1444 and see how that changes it?

Good point. That was rather careless of my parameter setting to filter out 1444 hands as well as [32]44 hands which ought to rebid 1NT. South now does not have :

 

* 6 diamonds

* 4 spades

* 5 diamonds and 4 clubs (but could have 4 diamonds and 4 clubs)

 

Note that South always bids 1D with 4-4 in the minors -- I don't make any judgement calls on whether to override 4-4 in the minors to 1C.

 

I also added another stat, to track the average HCP of the singleton, and I increased the sample size to 100000 hands.

 

New results:

 

Average spade length = 2.22771

Average singleton spade HCP = 0.8676683039583936

0 spades = 0

1 spades = 13844 (4x1 = 8084)

2 spades = 49541

3 spades = 36615

 

Wow. That was quite a difference. So the majority of 1NT singleton rebids are 1444, and the odds against a singleton for the rebid are now 6.2:1 against.

[Jlall]

Wow. That was quite a difference. So the majority of 1NT singleton rebids are 1444, and the odds against a singleton for the rebid are now 6.2:1 against.

OK cool, this matches my experience having played this style a lot.

[Jlall]

For me, with 5332 I will usually pass 1NT unless my spades are very strong and the rest of my hand is pretty crappy (like your example hand).

 

With non-5332, I would usually bid 2S.

 

I have no idea what the numbers work out to, but I would guess I rebid 2S about 80% of the time.

Fred,

 

I would consider on this auction that most non 5332s would be able to bid 2H or 2D (for you probably bidding 2D via a 2C relay). Like 5-4 majors bids 2H obv, 5-4 with diamonds gets out in 2D.

 

So the only real non 5332s here hands with side clubs. Probably 5332s are more common than hands with side clubs (not sure?) so if you pass with most 5332s it seems like 80 % was an overbid.

 

Anyways I feel like you and I are pretty close in what we do actually. We seem to be the same with 5332...I guess I pass a lot with 5314 also when you wouldn't, but with 5134 I would bid very often and 5224 would depend on my suit quality (I would need good spades), and I would always bid with 5-5.

[Ant590]

Another (probably dumb question), do any of you rebid 1NT on a 4=1=4=4 after 1♦-1♥?

[eyhung]

For me, with 5332 I will usually pass 1NT unless my spades are very strong and the rest of my hand is pretty crappy (like your example hand).

 

With non-5332, I would usually bid 2S.

 

I have no idea what the numbers work out to, but I would guess I rebid 2S about 80% of the time.

Fred,

 

I would consider on this auction that most non 5332s would be able to bid 2H or 2D (for you probably bidding 2D via a 2C relay). Like 5-4 majors bids 2H obv, 5-4 with diamonds gets out in 2D.

 

So the only real non 5332s here hands with side clubs. Probably 5332s are more common than hands with side clubs (not sure?) so if you pass with most 5332s it seems like 80 % was an overbid.

 

Anyways I feel like you and I are pretty close in what we do actually. We seem to be the same with 5332...I guess I pass a lot with 5314 also when you wouldn't, but with 5134 I would bid very often and 5224 would depend on my suit quality (I would need good spades), and I would always bid with 5-5.

This is actually a good discussion for me because I just played a hand where my partner held

 

AQxx 432 ATxx A2

 

Matchpoints, both vul

 

Our auction went :

 

1D 1H

1NT [1S anti-system] 2H

?

 

Partner passed, I thought he should have invited to 3H given the immense power of aces in a suit contract.

 

Surprisingly, when I simmed the hand, if partner is guaranteed to hold 6 hearts (but never 6-4 shape) with 4-9 HCP, then game is 55%, indicating he should bid 4H!

A big factor is that the opponents are passing -- meaning we get good breaks.

 

After adding decent 5-card heart suits (QJTxx or better) to the mix, game is 46%, suggesting an invite is probably ok, even at matchpoints.

 

Now that I can see some better judgement parameters for the rebid of 2H (never 5332 unless weak outside hearts, always otherwise), I'll be happy to rerun this.

[Jlall]

Surprisingly, when I simmed the hand, if partner is guaranteed to hold 6 hearts (but never 6-4 shape) with 4-9 HCP, then game is 55%, indicating he should bid 4H!

Where do you get this? This number could easily mean inviting is correct (and does mean that to me). If you want to try to prove that bidding game > inviting you need to prove that game is better than 50 % on hands where partner passes your invite. It's tough/impossible to simulate judgment but I bet if you give partner 4-6 and 6 hearts game is not better than 50 %.

 

 

But now simulations are getting dumb since we're just using HCP, so we might as well think about it from a bridge point of view. Bidding 3H on this auction shows a very good hand. Generally a primed out max with 3 hearts. That is what we have. Surely we can respect partner's judgment to be pretty good when we are able to describe our hand very well. The only time bidding game would be better than inviting is if we were not describing our hand that well.

 

Let's say game was 80%, but partner knew our exact hand if we bid 3H. We would obviously choose to bid 3H right? An extreme example, but you get the point. Partners range is extremely wide right now, ours will be extremely narrow. He should make the final decision.

 

Also, I would very often, much more than I would over 1D p 1S p 1N, go back to a 5 card heart suit on the auction 1D p 1H p 1N. 1H here is never a singleton, and there are more unbalanced hands with 5 hearts that we can have that don't get to show their second suit.

 

For instance 1D p 1S p 1N with 5-4 in either red suit we go back to that red suit. After 1D p 1H p 1N we can only go back to the second suit in one case, when it's diamonds. When we have 4-5 in the majors we go back to hearts. This increases the amount of times we will need to rebid our 5 card major, not even factoring in that it's less risky given that partner never has a stiff.

[eyhung]

Surprisingly, when I simmed the hand, if partner is guaranteed to hold 6 hearts (but never 6-4 shape) with 4-9 HCP, then game is 55%, indicating he should bid 4H!

Where do you get this? This number could easily mean inviting is correct (and does mean that to me).

Justin, you are correct. To rephrase: given a "false dilemma" of bidding 4H and passing 2H, bidding 4H rates to be the better choice. But this ignores the superior third choice, the invite. Obviously inviting is superior to bidding 4H for the reasons you mentioned. I just wanted to highlight to my disbelieving partner that if I held 6, just blasting game was better than passing. :(

 

And yes, the rebid of 2H tends to be 5 cards even more than the rebid of 2S. So the concept of "2H guarantees 6" is flawed. But the result that game is percentage opposite 6 hearts was not immediately obvious to me or my partner.

 

By the way, one nice thing about all this simulation work is that I am building up a library of functions which I can use to capture judgement heuristics and then reuse them for different hands in similar situations. As you can see this library is currently in a primitive state, and I find your comments invaluable to refining my functions.

[Jlall]

Are you really that surprised? You would bid 4H opposite a weak 2 without any qualms probably. Quick tricks + ruffing value + 3 trumps is a great hand opposite a 6 card suit.

[eyhung]

Are you really that surprised? You would bid 4H opposite a weak 2 without any qualms probably. Quick tricks + ruffing value + 3 trumps is a great hand opposite a 6 card suit.

You haven't seen some of the weak twos we open. :(

 

Just kidding, I'm not that psycho. Point taken.

[fred]

So the only real non 5332s here hands with side clubs. Probably 5332s are more common than hands with side clubs (not sure?) so if you pass with most 5332s it seems like 80 % was an overbid.

80% could easily be off - I was really just guessing what the number felt like from experience (versus guessing at a computation). Also, my guess was based on the general class 1m-1M-1NT as opposed to this specific auction. For some reason my brain doesn't give me a sense of what the numbers have been for the various auctions in this class. Maybe I need to play some more hands :(

 

I normally play Reverse Flannery so side hearts is not a possibility for me anyways, but agree with your general point that normally in this auction side clubs is the only possibility for non-5332 hands that contain exactly 5 spades.

 

Also agree that we are close to seeing eye-to-eye on this one.

 

Fred Gitelman

Bridge Base Inc.

www.bridgebase.com

[fred]

Eugene,

 

Your results are interesting - thanks.

 

I would be interested in knowing how much difference it makes if you ignore all constraints on the opponents' hands. If not too much trouble, can you please try that and post the results?

 

This request is not in any way relevant to the discussion - I am just curious.

 

I might be confused since I have never used your general methodology before, but I am not sure you are doing this right. I think the idea should be to always give North a hand with exactly 5 spades that would either pass 1NT or bid 2S and see how many spades South has on average under the appropriate constraints.

 

If I understand what you have said (sorry in advance if I have not) you are including hands for North that contain 4 spades, 6+ spades, and hands with at least enough strength to invite game. To answer this question properly I think you should take these hands out of the mix.

 

Thanks,

 

Fred Gitelman

Bridge Base Inc.

www.bridgebase.com

[eyhung]

Eugene,

 

Your results are interesting - thanks.

 

I would be interested in knowing how much difference it makes if you ignore all constraints on the opponents' hands. If not too much trouble, can you please try that and post the results?

 

This request is not in any way relevant to the discussion - I am just curious.

 

I might be confused since I have never used your general methodology before, but I am not sure you are doing this right. I think the idea should be to always give North a hand with exactly 5 spades that would either pass 1NT or bid 2S and see how many spades South has on average under the appropriate constraints.

 

If I understand what you have said (sorry in advance if I have not) you are including hands for North that contain 4 spades, 6+ spades, and hands with at least enough strength to invite game. To answer this question properly I think you should take these hands out of the mix.

 

Thanks,

 

Fred Gitelman

Bridge Base Inc.

www.bridgebase.com

I actually did remove the opponent constraints out of curiosity :

 

1 spade = 12.91% (7.47% are 4x1s)

2 spades = 48.69%

3 spades = 38.4%

 

So it's similar, but slightly less likely to be singleton.

 

This is including hands where north has 4 spades, 6 spades, gf, weak, etc.

 

I actually wasn't trying to answer the question of how often we should rebid 2S over a 1NT rebid in this auction, I was just trying to see how often South would have a singleton spade after a real-life auction of 1D 1S 1NT with no enemy bidding. 30:1 felt wrong given that I have also taken to rebidding 1NT with a singleton.

 

I will be happy to remove game-invitational+ hands, and hands without exactly 5 spades from the mix and report the results.

[fred]

30:1 felt wrong given that I have also taken to rebidding 1NT with a singleton.

I am not sure that 30:1 is right either, but there were several things you did that were different than what I did:

 

- You didn't include (23)44 in your initial simulation

 

- You included 1444 hands in some of your simulations

 

- You included hands with 3-card support and small doubletons in some of your simulations

 

- You made assumptions about the opponents' hands

 

- Your methodology results in "dependent probabilities" (a good thing!) while mine does not

 

If you feel kind enough to check my 30:1 number, you should do this:

 

1) Make South the only hand you constrain and give South 1453 with 12-14 HCP. I get 0.11%.

 

2) Make South the only hand you constrain and give South 2 or 3 spades, 2 to 4 hearts, 4 or 5 diamonds, 2 to 4 clubs, and 12-14 HCP. I get 3.15%. I now see that I did this wrong as far as the actual problem is concerned since I was including 2254, but I would still be interested in seeing if you get the same %s as me.

 

Fred Gitelman

Bridge Base Inc.

www.bridgebase.com

[eyhung]

1) Make South the only hand you constrain and give South 1453 with 12-14 HCP. I get 0.11%.

 

2) Make South the only hand you constrain and give South 2 or 3 spades, 2 to 4 hearts, 4 or 5 diamonds, 2 to 4 clubs, and 12-14 HCP. I get 3.15%. I now see that I did this wrong as far as the actual problem is concerned since I was including 2254, but I would still be interested in seeing if you get the same %s as me.

Generating 1 million hands

 

1) 0.1154%

2) 3.1474%

 

 

-----------------------

 

Sample size: 1000 hands

North has exactly 5 spades, at most 9 HCP, South has a hand that would open 1D and rebid 1NT (and would have raised on some 3-card spade suits, as described earlier), E/W can have any hand (including those that would bid in real life)

 

South average spade length = 2.271

1 spade = 132

2 spades = 465

3 spades = 403

4x1 = 84

2S makes but 1NT doesn't = 188

1NT makes but 2S doesn't = 121

Both make = 326

Both go down = 365

Average tricks in spades = 7.498

Average tricks in NT = 6.288

 

----------------------

 

Sample size: 1000 hands

Same N/S parameters, but now E/W are operating under the pass_functions described earlier.

 

Average spade length = 2.23

1 spades = 140

2 spades = 490

3 spades = 370

4x1 = 77

2S makes but 1NT doesn't = 176

1NT makes but 2S doesn't = 110

Both make = 383

Both go down = 331

Average tricks in spades = 7.672

Average tricks in NT = 6.433

 

-----------------------

 

Apologies for the smaller sample size, but double-dummy analysis takes longer to run, and we're getting similar numbers (13-14% spade singletons) as the larger sample sizes. Bottom line, 2S seems to be superior to 1NT at IMPs on a 5-bagger even if we rebid 1NT fairly freely with a singleton.

[eyhung]

Note that I didn't put any additional constraints on the North hand such as removing hands that would judge to pass 1NT, such as 9 HCP 5332s.