[straube]

nullve, on 2015-July-17, 09:57, said:

Another example: weak hands with (41)44 shape. Using the proposed scheme of openings I would have to choose the least lie among Pass (denying a singleton/void), 2D/H (promising 5+ m unless unless 4+H/5+S) and 2S (5+m4+Om). Yuck.

Not sure how to read this. Hopefully you are agreeing with Zelandakh's criticism of your structure. I sure do.

Rather than try to destroy the opponents' bidding or enable 3rd hand to more freely preempt, I think it's better to open or preempt hands that are likely to produce tricks. Those are plenty enough.

I think you've done a fine job explaining your idea and I think it's fine to promote and defend an idea as well as solicit criticism or help. At this point, however, maybe take stock and see how many folks agree with your design goals. I.e. there will be more interest in better ways to describe hands that we want to describe than ones that we don't.

[Free]

2♣ is definitely a BSC! Yes, the weak two's are included, but a 5M-4m hand is included as well and that is NOT a weak two (it's a Muiderberg). So there are weak versions without an anchor suit other than standard weak two's (= weak with a 6 card suit), which make it BSC. Saying 20 times that you're not a bridge lawyer is fine, and many people playing natural weak two's might open 5M-4m hands from time to time, but that doesn't change the fact that you can't bend the rules... Accept it: the 2♣ opening is BSC

I think the 2♣ opening is overloaded and you just can't handle competition very well. Do you really think opponents will just let you bid 2♣-2♦-2M all the time? Including strong options will only make it worse because you lose too much preemptive options. When having weak versions only, and since you always promise a Major, you can do so much more with 2NT+ responses.

Note: having cool names for conventions doesn't make the convention cool

[nullve]

straube, on 2015-July-17, 23:04, said:

Not sure how to read this. Hopefully you are agreeing with Zelandakh's criticism of your structure. I sure do.

Yes, I agree with him in the sense that I wouldn't be happy to open, say, 2S (or whatever) with K-KQJ-xxxx-xxxxx. In fact, I would pass, pretending to be balanced. Of course, if that's a tendency of mine on hands like this (singleton king, low ODR), I really shouldn't say that Pass denies a singleton or void. But in a "meme-sized" (i.e. rough, easily remembered) description of P-P P, that seems (or seemed) accurate enough.

Quote

Rather than try to destroy the opponents' bidding or enable 3rd hand to more freely preempt, I think it's better to open or preempt hands that are likely to produce tricks. Those are plenty enough.

Maybe it is, but isn't that at least debatable?

Quote

maybe take stock and see how many folks agree with your design goals. I.e. there will be more interest in better ways to describe hands that we want to describe than ones that we don't.

I've presented three ideas/conventions that are related in the way that

Multi Squared = rubbish => MuSHroom = rubbish => P-P P (with 2C+ = MuSHroom) = rubbish

Fortunately, the opposite implications don't hold, so there is no reason to buy the whole package. My own view is that Multi Squared and MuSHroom are sound conventions while P-P P may be nothing more than an interesting (i.e. not obviuosly bad) idea.

[nullve]

Free, on 2015-July-18, 02:32, said:

2♣ is definitely a BSC! Yes, the weak two's are included, but a 5M-4m hand is included as well and that is NOT a weak two (it's a Muiderberg). So there are weak versions without an anchor suit other than standard weak two's (= weak with a 6 card suit), which make it BSC. Saying 20 times that you're not a bridge lawyer is fine, and many people playing natural weak two's might open 5M-4m hands from time to time, but that doesn't change the fact that you can't bend the rules...

I actually include fewer patterns than many who play Garbage Multi. Where I live, they typically include 5M(332) as well as 6 M and 5M4+m That has never caused a problem for anyone here although we're trying to follow the WBF Systems Policy. As for the WBF definitions of '(standard) weak two's' and 'Muiderberg' you're impliclty referring to, I wasn't aware they existed.

Quote

I think the 2♣ opening is overloaded and you just can't handle competition very well.

Maybe, but then the same is true of an identically defined 2D opening.

Quote

Do you really think opponents will just let you bid 2♣-2♦-2M all the time?

I wouldn't even if they let me.

Quote

2D is not Including strong options will only make it worse because you lose too much preemptive options. When having weak versions only, and since you always promise a Major, you can do so much more with 2NT+ responses.

Agree. I think "strong options according to taste" has been misleading people into thinking that at least one strong option has to be included, although 'zero or more strong options' was what I intended. Sorry.

Quote

Note: having cool names for conventions doesn't make the convention cool

Agree. I've always found it difficult to come up with good names for bits of bidding structure. But if the structure doesn't have a name, or if the name is too long, it becomes very cumbersome to talk about it. Also, if the name I give it isn't descriptive enough, it may be hard to remember what it's referring to. So I've tried to find catchy-but-descriptive names. 'Multi 2C' was unfortunatley taken, so I decided to go with 'Multi Squared' instead, which is sort of descriptive (to me, at least). 'MuSHroom' also serves its purpose, I think.

[nullve]

I thought I should say a bit more about the different scenarios after the "Multi" 2M rebid in the case that Responder has < inv values and a potentially misfitting hand, although it seems that people are beginning to get the basic idea now - hopelessly flawed or not.

Recall that if Opener is weak, he will always have one of the following hand types:

1) 6 H
2) 6 S
3) 5H4+m
4) 5S4+m

Now assume that Responder has one of the following (common) shapes:

a) 1444 or 13(54)
b) 4144 or 31(54)
c) 1-S6H or 15(43)
d) 6S1-H or 51(43)

The bidding for each combination:

1a) 2C-2D; 2H-3C; 3H-4H; P
1b) 2C-2D; 2H-P [assuming 6 H]
1c) 2C-2D; 2H-P [hoping for a 7-card or better H fit, hitting p with 6 H]
1d) 2C-2D; 2H-P [assuming 6 H]
2a) 2C-2D; 2S-P [assuming 6 S]
2b) 2C-2D; 2S-3C; 3S-4S; P
2c) 2C-2D; 2S-P [assuming 6 S]
2d) 2C-2D; 2S-P [hoping for a 7-card or better S fit, hitting p with 6 S]
3a) 2C-2D; 2S-P [assuming 6 S. Oops! 3-1 fit or worse]
3b) 2C-2D; 2S-3C; P/3D-P
3c) 2C-2D; 2S-P [assuming 6 S. Oops! 3-1 fit or worse]
3d) 2C-2D; 2S-P [hoping for a 7-card or better S fit]
4a) 2C-2D; 2H-3C; P/3D-P
4b) 2C-2D; 2H-P [assuming 6 H. Oops! 3-1 fit or worse]
4c) 2C-2D; 2H-P [hoping for a 7-card or better H fit]
4d) 2C-2D; 2H-P [assuming 6 H. Oops! 3-1 fit or worse]

As the spectacular accidents in 3a), 3c), 4b) and 4d) are bound to happen*, like giant earthquakes in California, Multi Squared will look like rubbish unless one is able to deal with it philosophically when they occur. That may depend on the (perceived) frequency of the accidents and the (perceived) size the damage, just as when playing structures like

* EHAA (Opener has no forcing opening bid available on strong unbal. hands)
* standard Precision 2C (inevitable accidents when Responder is weak, occasionally the size of a game swing)
* the Turbo convention (heightened risk of missing 2+ key cards compared with RKC)*
* assumed fit preempts (p may not have the assumed fit)

or even

* RKC (see http://www.eurobridg...ns/21ThuPg4.htm for an amusing example)
* preempts in general (p may have less support than hoped for)
* just about any bidding structure, really (bad trump breaks, finesses are off...)

In my (adimittedly subjective) experience, which you may have good (even mathematical) reason to distrust, accidents as in 3a), 3c), 4b) and 4d)) aren't nearly as frequent as some people might think. And although they tend to benefit the opponents, sometimes by more than game swing, they will occasionally benefit the bidding side, as when opps are cold for game in the same major suit.

All in all, I'm not claiming this is a risk free way of playing bridge (there isn't any), but it might still be good bridge.

* As gwnn pointed out, the risk is greater the lesser the suit length disparity in Responder's major suits is.
** The comparison with Turbo or RKC might be the most interesting, but I won't say more about it now.

[gwnn]

The point is that opponents are well equipped to avoid the disasters if they want to. You are not well equipped to avoid the disasters, and may be partially relying on your opps to rescue you from them, which is never a good policy to have. But I think we've been over this before and you clearly do not care too much about these considerations so good luck with your method.

[nullve]

gwnn, on 2015-July-20, 03:04, said:

The point is that opponents are well equipped to avoid the disasters if they want to.

To give you a counterexample, I'd need to know your defensive method, or else you could just choose or make up one ad hoc. But I'll be generous and assume you're right.

Quote

You are not well equipped to avoid the disasters, and may be partially relying on your opps to rescue you from them, which is never a good policy to have.

My previous post was largely about disasters I can't avoid even in principle - unless opps are doing something really unexpected to help me out, that is. So am I partly relying on opps to rescue me? Just barely, as I believe (based on my own imperfect experience) that disasters of this type would be quite rare even if opps were allowed to choose their defence ad hoc. In practice, opps - even you? - will continue overcalling on, say, good hands with a 6-card or longer major, thereby automatically rescuing me from at least some disastrous 3-1 or worse fits.

[gwnn]

I was talking about beginners or people who are uncomfortable around artificial systems who will pass on various hands that you and I consider automatic overcalls (yes they may even be scared by your methods and pass with something like AKxxxx xx Axx xx or what not). However it is kind of tough to know which category your opps belong to since on the other hand there will be opps who are happy to overcall on AQxxx xx xxx Axx and their passes will be more meaningful. Unfortunately you cannot really ask which kind they are since they might not even know themselves. I did not say I was such a beginner so yes you will likely be able to draw decent conclusions from my passes although now that I'm posting this I might just pass a few times for fun if we meet I hope you understand that giving two options for your opps before your big multi moment helps them a lot and that rebidding 2S with hearts hinders you a lot and that the randomness you create on yourself is significant. I think you do but you somehow cross your fingers and hope that it will not matter. Good luck with it anyway (I mean this only 10% sarcastically and 90% genuinely). But in the name of everything that is holy do not do it when you are vulnerable.

[nullve]

gwnn, on 2015-July-20, 05:51, said:

now that I'm posting this I might just pass a few times for fun if we meet

I know you're half joking, but you're touching a couple of interesting points.

To describe the uncontested responses to 2C is the same as describing Responder's options over 2C-(P), where P has the standard/expected meaning. If your meaning of P is non-standard*, in which case I'm entitled to know about it, I might adapt by using a different scheme of responses. For instance, in the extreme case that P is forcing, I might make heavy use of Pass, thereby gaining a lot of extra bidding space and maybe also putting pressure on Advancer. If the only difference between a standard P and yours is that you will occasionally pass on a good hand with 6+ M, I personally wouldn't change anything, because even though the 2C-2D; 2M-P accidents are now more likely to occur, your (tongue-in-cheek?) tactics may backfire. You said that opps are well equipped to avoid disasters (and I assumed you were right, for the sake of argument), but if you choose not to overcall on some good hands with 6+ M, how can you always avoid being stolen from when the bidding goes (2C)-P-(2D)-P; (2M)? After all, it's precisely when opps have good hands that the 2C-2D; 2M-P accidents have any chance of benefitting the bidding side. Ironically, you may have given me one of the advantages of a Multi 2H opening, even one you've been talking warmly about, for free.

* or frequently psyched, which effectively changes its meaning

[gwnn]

You're not really getting my point which I thought I made already, in fact I addressed your reply already preemptively. There will be oppoments who know what they are doing, in that case you can rely on their passes. There will also be opponents who are shell-shocked and will pass throughout and in that case you'll have a lot of problems drawing any inferences from their actions. There will not just be "the opponents" but two groups of them. Unfortunately it might be difficult for you to ascertain which group your opponents belong to so you might have a lot of problems in guessing. Statistically of course their passes are more meaningful than white noise but you will have another problem (identification of your opponents as well as identification of partner's suit) to worry about. My point was: In principle, your opponents can help themselves, partially helping you too, but in practice, some opponents will not help themselves or you. Actually this might be a good moment to think of full disclosure since I might want to know that your follow-ups have this 2H multi structure (something that a lot of people will not tell their opps, not pointing my finger at you), which may influence opps' decisions, for example passing more often than normal.

[gwnn]

Come to think of it, say I have AKJxxx x Qxx xxx and I decide (either a priori or in the spur of the moment) as 2nd seat "ok I will pass with this for one round and see what happens", and then it comes back to me as:

2C-p-2D-p
2S-?

And you actually have hearts and I have spades? Of course I will pass now, knowing that you are in a stupid contract and will likely stay there. Partner had the option to double 2D with any 12-14 balanced or 16+ (simple enough and many people play these methods) so we are likely not missing game. It seems like actually passing with a long major suit is a pretty good deal, particularly so with spades. I haven't thought this through exactly but you can see how a lot of people can stumble into this situation without even trying to come up with some genius, deep defence, and you're already in trouble.

[nullve]

gwnn, on 2015-July-21, 05:39, said:

you can see how a lot of people can stumble into this situation without even trying to come up with some genius, deep defence, and you're already in trouble.

I absolutely agree with you here. But AKJxxx-x-Qxx-xxx is a quite marginal overcall, anyway, and I thought the idea was to pass also with stronger hands.

[gwnn]

Well yes probably also pass with some stronger hands but definitely not forcing (which I know you did not suggest as a defence, just as an extreme example). I don't know honestly. I think winging it would already do quite well against this method. This might sound insulting but I think it's just the simple truth of the matter.

All I am saying is that "I have 3 hearts and 1 spade so partially based on my opps' passes, I will assume my partner has 6 spades and not 5 hearts and pass 2♠" will be a very tenuous proposition. Which I think you know and agree with, so we're back in "going around in circles" mode. I basically am confused on why you are still thinking of playing this method since you seem to be saying "yes all of the criticisms are valid but some of them apply to a lesser degree to other methods too." Yes I guess it's just a matter of taste and I guess it will be a matter of whether your minor-oriented/canape/three-suited 2M openers can make up for the dozens of imps your 2♣ openings will bleed. I am guessing not but I am guessing you disagree with the "dozens of imps" and/or my guess.

[nullve]

gwnn, on 2015-July-21, 05:33, said:

Actually this might be a good moment to think of full disclosure since I might want to know that your follow-ups have this 2H multi structure (something that a lot of people will not tell their opps, not pointing my finger at you), which may influence opps' decisions, for example passing more often than normal.

The subject of full disclosure is an interesing one, and although I haven't thought very deeply about it, here's what I think:

Basically, I view bidding theory as a kind of two-player game, often played by one bidding theorist against himself for lack of opponents, but also by partnerships against other partnerships in real life encounters, and to a lesser degree by forumers against other forumers in threads like this. This game (actually only half of it - see below) respects a move order where Player I starts by assigning a meaning to at least some of the following calls: P, 1C, ..., 7N. Player II then assigns a meaning to some of the sequences (P)-P, (P)-1C, ..., (P)-7N, (1C)-P, (1C)-X, (1C)-1D, ..., (1C)-7N, and so on. Then it's Player I' turn again, and he may assign meanings to some sequences such as P-(P)-P, ..., P-(P)-7N or 2D-(X)-P, 2D-(X)-XX, 2D-(X)-2H, ..., 2D-(X)-7N. And so on and so on. There is also a dual game (the other half of the whole game) where Player II starts first.

I think this is the only reasonable way the "game" of bidding theory can be played, so if e.g. an opponent wants to know my 1N defence before he decides upon his 1N range, I think he's got it exactly backwards. Still, I'd be happy to tell my opponent about my structure after 2C-(P)-2D; 2M, for each of his choices of P.

[gwnn]

I mean, won't you always have

2♣-p-2♦-p
2M as 6+M or 5oM4m? Assuming pass by 4th seat includes all hands from 0-10 balanced (say), does it really matter that they occasionally pass with 6 or 7 spades as well? At what point will you say "aha OK in that case 2H shows hearts and 2S shows spades"?

[nullve]

gwnn, on 2015-July-21, 08:36, said:

I mean, won't you always have

2♣-p-2♦-p
2M as 6+M or 5oM4m?

Yes, unless either pass is something really out of the ordinary, like F1.

Quote

Assuming pass by 4th seat includes all hands from 0-10 balanced (say), does it really matter that they occasionally pass with 6 or 7 spades as well?

No, not to me.

Quote

At what point will you say "aha OK in that case 2H shows hearts and 2S shows spades"?

Only when the meaning of Pass by Advancer allows me to pass with some hands as Opener, e.g. when

2C-(P)-2D-(P)=F1.

So I think you've got everything right.

[helene_t]

By not utilising more than two rebids we use the bidding space inefficiently. When opener is max with five cards M his third bid is 3nt and his minor suit is still unknown.

[nullve]

helene_t, on 2015-July-21, 10:06, said:

By not utilising more than two rebids we use the bidding space inefficiently.

That's especially true in a weak-only version where of Multi Squared where 2N+ are also available rebids.

Quote

When opener is max with five cards M his third bid is 3nt and his minor suit is still unknown.

Yes. So it looks bad compared to e.g. Muiderberg, but ok (or even good!) compared to some versions of Multi 2D. It has worked ok in practice, but in the "lab" I've toyed with a "muiderbergified" scheme:

2C-2D; 2M-2N; ?:

3C = non-max, 6 M or 5OM4+m (i.e. a third Multi!)

3C¹ = allowed!

3D = reality check

3M = 6 M

3OM = 5OM4+m

3M = P/C

3OM = P/C

3D = non-max, 5OM4+D
3H = max, 5OM4+C
3S = max, 5OM4+D
3N = max, 6 M

EDIT: Structure corrected. I was mixing up two versions, but this is the simplest one.

¹ [11 Aug 2016:] Meant to write 'P', not '3C'.

Added, starting 21 January 2017:

Spoiler

Experiments:

Spoiler

21 Jan 17 [with some changes in notation 9 Aug 2017]:

Spoiler

This is what my 2♣ structure in 1st seat NV currently looks like.

2♣: as in the comment from 20 Jan 17 below the OP

(Legend: non-MAX = rules of 9-15; MAX = rules of 16-18; WK = rules of 9-18; STR = rule of 31+; R1 = < GF opposite "7" (rule of 16); R2 = GF only opposite "7+" (rule of 16+); R3 = unconditional GF (Responder always assumes "4+" (rule of 13+))

2♣-?:

P: allowed!
2♦ = R1, either 1- M, 3S3+H or 6+M2-OM / R2+, doesn't worry about 3♣ over 2♣-2♦; 2M-2N
...2♥ = non-MAX, 3-S7H / WK, either 5S3-H4+m or 3-S6H
......P = R1, either 1- H or 15(43) or 2-S6+H
......2♠ = R1, 3S3+H (P/C)
......2N = R2+
........."muiderbergified" scheme:
.........3♣ = non-MAX, 5S3-H4+C / 3-S6H
............P = allowed (Responder is assuming Opener has 4+ C)
............3♦ = reality check
...............3♥ = non-MAX, 3-S6H
...............3♠ = 5S3-H4+C
...............3N = MAX, 3-S6H
.........3♦ = non-MAX, 5S3-H4+D
.........3♥ = MAX, 5S3-H4+C
............3♠ = relay
...............3N = 2- H
...............4♣+ = 3 H
.........3♠ = MAX, 5S2-H4+D
.........3N = MAX, 5S3H4+D
......3♣ = R1, 1-S4-H4+C
.........P = WK, 5S4+C
.........3♦ = WK, 5S4+D
.........3♥ = WK, 6 H
.........3♠+ = STR, nat.
......(...)
...2♠ = non-MAX, 7S3-H / WK, either 3-S5H4+m or 6S3-H
......P = R1, either 1- S or 51(43) or 6+S2-H
......2N = R2+
........."muiderbergified" scheme:
.........3♣ = non-MAX, 3-S5H4+C / 6S3-H
............P = allowed (Responder is assuming Opener has 4+ C)
............3♦ = reality check
...............3♥ = 3-S5H4+C
...............3♠ = non-MAX, 6S3-H
...............3N = MAX, 6S3-H
.........3♦ = non-MAX, 3-S5H4+D
.........3♥ = MAX, 3-S5H4+C
............3♠ = relay
...............3N = 2- S
...............4♣+ = 3 S
.........3♠ = MAX, 3-S5H4+D
.........3N = MAX, 3-S5H4+D
......3♣ = R1, 1-H3+C
.........P = WK, 5H4+C
.........3♦ = WK, 5H4+D
.........3♥/3N+ = STR, nat.
.........3♠ = WK, 6 S
......(...)
......3♥ = R1, 3S3+H
.........P = WK, 5 H
.........3♠ = WK, 6 S
.........3N+ = STR, nat.
...2N+ = STR, relay structure
2♥ = R1, 2+S2H (P/C)
...P = WK, 5+ H
...2♠ = WK, 5+ S
...2N+ = STR, relay structure
2♠ = R1, 2S3+H (P/C)
...P = WK, 5+ S
...2N+ = STR, relay structure, except that
...3♦ = rule of 9-18, 5+ H / STR, part of relay structure
......3♥ = relay
..........P = rule of 9-18
..........3♠+ = part of relay structure
2N = R2, 2S4+H3+C, would have had trouble "guessing" over 2♣-2♦; 2♠-2N; 3♣
...3♣ = non-MAX, 5S4+C
...3♦ = non-MAX, 5S4+D
...3♥ = non-MAX, 5 H
...3♠ = non-MAX, 6 S
...3N = MAX, 5 S
...(...)
...4♥ = 6 H
...[26 April 2018: 4♠ = MAX, 6 S?]
3♣ = R2, 3+S2H, would have had trouble "guessing" over 2♣-2♦; 2♥-2N; 3♣
...P = non-MAX, 5H4+C
...3♦ = non-MAX, 5H4+D
...3♥ = non-MAX, 6 H
...3♠ = non-MAX, 5 S
...3N = non-MAX, 5 H
...(...)
...[26 April 2018: 4♥ = MAX, 6 H?]
...4♠ = 6 S
3♦ = ?
3♥ = R1, 4+S4H (P/C)
3♠ = R1, 4S5+H (P/C)
4♣ = asks Opener to transfer if weak
4♦ = asks Opener to bid his major if weak
4M = to play if Opener is weak

I also play "muiderbergified" schemes over 2♦-2N and 2♥-2N. 23.01.17: The full structures:

2♦-?:

P: allowed
2♥ = P/C, includes the "old" P/C 3♣ response
...P = 4+ H
...2♠ = 4S5+m
...2N+ = STR, 5+ S, unbal., relay structure, except that
...2N = 0-10, 4144 / STR, part of relay structure
......3♣ = C pref. opposite 4144
.........P = 0-10
.........3♦+ = STR, part of relay structure
......3♦ = D pref. opposite 4144
.........P = 0-10
.........3♥+ = STR, nat.
2♠ = to play opposite WK
...P = WK
...2N+ = STR, 5+ S, unbal., relay structure
2N = R2+, doesn't worry about 3♣ over 2♦-2N / R3+
...[Ignoring the possibility that Opener can have 4H(441):]
...3♣ = non-MAX, 5+ C / 5+ H
......P = allowed (Responder is assuming Opener has 5+ C)
......3♦ = reality check
.........3♥ = non-MAX, 5+ H
.........3♠ = non-MAX, 3-H5+C
.........3N = MAX, 4S5H
.........4♣ = MAX, 4+S6+H
.........4♦ = 5S5H
...3♦ = non-MAX, either 5+ D or 4144
...3♥ = MAX, 5+ C
...3♠ = MAX, 2-H5+D
...3N = MAX, 3H5+D
3♣ = R2, usually 3+H3+C, would have had trouble "guessing" over 2♥--2N; 3♣
...P = non-MAX, either 5+ C or 4414
...3♦ = non-MAX, 5+ D
...3♥ = non-MAX, either 5+ H or 4414
...3♠ = MAX, 4S2-H
...3N = MAX, 4S3H
...4♣+ = MAX, 5+ H
3♦ = ?
3♥ = ?
3♠ = preemptive
(...)

2♥-?:

(...)
2♠ = P/C, includes the "old" P/C 3♣ response
...P = 4+ S
...2N = either 1444, 5D3+C or 3S6+D
......3♣ = C pref. opposite 1444
.........P = 1444 or 1453
.........3♦ = 3451
......3♦ = D pref. or no m pref. opposite 1444
...3♣ = 5+ C
...3♦ = 2-S5+D
2N = R2+, doesn't worry about 3♣ over 2♥-2N / R3+
...[Ignoring the possibility that Opener can have 4H(441):]
...3♣ = non-MAX, 5+ C / 5+ S
......P = allowed (Responder is assuming Opener has 5+ C)
......3♦ = reality check
.........3♥ = non-MAX, 5+ C
.........3♠ = non-MAX, 5 S
.........3N = MAX, 5S4H
.........4♣ = non-MAX, 5S5+H
.........4♦ = non-MAX, 6+S4H
...3♦ = non-MAX, 5+ D
...3♥ = MAX, 3-S5+C
...3♠ = MAX, 2-S5+D
...3N = MAX, 3S5+D
3♣ = R2, usually 3+S3+C, would have had trouble "guessing" over 2♥--2N; 3♣
...P = non-MAX, either 5+ C or 1444
...3♦ = non-MAX, 5+ D
...3♥ = non-MAX, either 5+ S or 4441
...3♠ = MAX, 2-S5+D
...3N = MAX, 3S4H
...4♣+ = MAX, 5+ S
3♦ = ?
3♥ = preemptive
(...)

[Probably errors here and there.]

8 Feb 2017:

Spoiler

If non-MAX (say, of 9-15) hands with 4M3-OM5+C are treated as bad C preempts (and opened either 2♠, 2N or 3♣, depending on the remaining Mushroom structure), then it's possible to play

2♦-2N; ?:

3♣ = 4+ H
...3♦ = GF relay
......3♥ = MIN
.........3♠ = relay
............3N = 4S4H4+D
............4♣+ = 5+ H
......3♠ = MAX, 4S4H4+D
......3N = MAX, 4S5H
......4♣ = MAX, 4S6+H
......4♦ = MAX, 5S5H
...(...)
3♦ = non-MAX, either 4S3-H5+D or 4144
3♥ = MAX, either 4S3-H5+C or 4144
...3♠ = relay
......3N = 2- H
......4♣+ = 3 H
3♠ = MAX, 4S2-H5+D
3N = MAX, 4S3H5+D

2♥-2N; ?:

3♣ = 4+ S
...3♦ = GF relay
......3♥ = MIN
.........3♠ = relay
............3N = 4S4H4+C
............4♣+ = 5+ S
......3♠ = MAX, 4S4H4+C
......3N = MAX, 5S4H
......4♣ = MAX, 5+S5+H
......4♦ = MAX, 6+S4H
...(...)
3♦ = MIN, either 3-S4H5+D or 1444
3♥ = MAX, either 3-S4H5+C or 1444
...3♠ = relay
......3N = 2- S
......4♣+ = 3 S
3♠ = MAX, 2-S4H5+D
3N = MAX, 3S4H5+D

18 April 2017:

Spoiler

One idea I like more and more is to keep non-MAX hands with 5+ C in 2♦/♥ and use both 2N and 3♦ as relays, just like I've suggested over 2♠. (The idea could also be used over 2♣-2♦; 2M.) For example:

2♦-?:

(...)
2N = NF relay
...P = non-MAX, either 5+ C or 4144
...3♣ = 5+ H or 4S4H4+D
...3♦ = non-MAX, 5+ D
...(...)
(...)
3♦ = relay, F4♥ opposite MAX
...3♥ = 5+ H or 4S4H4+D
......3♠ = NF
...3♠ = non-MAX, 3- H
...3N+ = MAX, 3- H
(...)

2♥-?:

(...)
2N = NF relay
...P = non-MAX, either 5+ C or 1444
...3♣ = 5+ S or 4S4H4+C
...3♦ = non-MAX, 5+ D
...(...)
(...)
3♦ = relay, F4♥ opposite MAX
...3♥ = non-MAX
......3♠ = relay
.........3N = 3- S
.........4♣+ = 5+ S
...3♠ = MAX, 5+ S or 4S4H4+C
...3N+ = MAX, 3- S
(...)

Replaced by:

Spoiler

9 Aug 2017: Idea: Play 2♣-2♦; 2M-2N; 3♣ and 2R-2N; 3♣ as ART and still be able to able to get out in 3♣ when Opener has non-MAX with C.

Main tool:

2♣-2N = "like P/C 3♣ over 2♣-2♦; 2♠, but INV"
2♣-3♣ = "like P/C 3♣ over 2♣-2♦; 2♥, but INV"
2R-3♣ = "INV P/C"

helped by

2♣-2M = "P/C OR INV, 5+M2-OM"
2♦-2♥ = "P/C OR INV, 3-S5+H2"
2♥-2♠ = "P/C OR INV, 5+S3-H"

so that no 5-3 major fits are missed.

For example:

2♣-?:

[26 April 2108: Legend (copied from 21 Jan 2017 entry): non-MAX = rules of 9-15; MAX = rules of 16-18; WK = rules of 9-18; STR = rule of 31+; R1 = < GF opposite "7" (rule of 16); R2 = GF only opposite "7+" (rule of 16+); R3 = unconditional GF (Responder always assumes "4+" (rule of 13+)]

2♦ = R1, either "potential misfit" or 3S(3)4+H OR R2, neither 5+M2-OM nor 3-4M2OM(3)4+C OR R3?
...2M = as above
......2N = INV+ relay
.........3♣+ = muiderbergified, but Responder will never pass 3♣
...So
...2♥ = non-MAX, 3-S7+H / WK, either 3-S6H or 5S3-H4+m
......P = R1, either 1- H, 2-S6+H or (probably the best thing to do with) 15(43)
......2♠ = R1, 3S(3)4+H (P/C)
......2N =INV+ relay
.........3♣ = non-MAX, 5S3-H4+C / 3-S6H
............P = allowed (Responder is assuming Opener has 4+ C)
............3♦ = reality check
...............3♥ = non-MAX, 3-S6H
...............3♠ = 5S3-H4+C
...............3N = MAX, 3-S6H
.........3♦ = non-MAX, 5S3-H4+D
.........3♥ = MAX, 5S3-H4+C
............3♠ = relay
...............3N = 2- H
...............4♣+ = 3 H
.........3♠ = MAX, 5S2-H4+D
.........3N = MAX, 5S3H4+D
......3♣ = R1, P/C (probably better to pass with 15(43))
......(...)
...2♠ = non-MAX, 7+S3-H / WK, either 6S3-H or 3-S5H4+m
......P = R1, either 1- S, 6+S2-H or (probably the best thing to do with 51(43)
......2N = INV+ relay
.........3♣ = non-MAX, 3-S5SH4+C / 6S3-H
............P = allowed (Responder is assuming Opener has 4+ C)
............3♦ = reality check
...............3♥ = 3-S5H4+C
...............3♠ = non-MAX, 6S3-H
...............3N = MAX, 6S3-H
.........3♦ = non-MAX, 3-S5H4+D
.........3♥ = MAX, 3-S5H4+C
............3♠ = relay
...............3N = 2- S
...............4♣+ = 3 S
.........3♠ = MAX, 2-S5H4+D
.........3N = MAX, 3S5H4+D
......3♣ = R1, P/C (probably better to pass with 51(43))
......(...)]
...2N+ = as above
2♥ = as above OR INV, 2-S5+H
...If WK (Opener may use the same way on STR hands):
...P = 5+ H / ?
...2♠ = 5+ S
2♠ = as above OR INV, 5+S2-H
...If WK (Opener may use the same bids on STR hands):
...P = 5+ S / ?
...2N = non-MAX, 5+ H (=> 3♣ = P/C)
...3♣ = MAX, 5H4+C
...3♦ = MAX, 5H4+D
...3♥ = MAX, 6 H
2N = INV PC w/ 2S3-4H(3)4+C?
...Maybe
...3♣ = non-MAX, 5S4+C
...3♦ = non-MAX, 5S4+D
...3♥ = non-MAX, 5+ H
...3♠ = non-MAX, 6+ S
...3N = MAX, 5 S
...4m = ?
...4♥ = MAX, 5+ H (or maybe use 4♣ for that?)
...4♠ = MAX, 6 S (or maybe use 4♦ for that?)
...?
...[not finished]]
3♣ = INV P/C w/ 3-4S2H(3)4+C?
...Maybe
...P = non-MAX, 5H4+C
...3♦ = non-MAX, 5H4+D
...3♥ = non-MAX, 6+ H
...3♠ = non-MAX, 5+ S
...3N = MAX, 5 H
...4m =
...4♥ = MAX, 6 H (or maybe use 4♣ for that?)
...4♠ = MAX, 5+ S (or maybe use 4♦ for that?)
...?
...[not finished]]
other = as above

2♦-?:

2♥ = as above OR INV, 3-S5+H*
...If WK:
...P = 4+ H / ?
...2♠ = 3- H
2N = GF relay
...3♣ = 5+ D
......3♦ = relay
.........3♥+ = A(♠,♦). See A(M,m) below.
...3♦ = 4+ H
......3♥ = GF relay, either with 3+ H or slam interest
.........3♠+ = B(♠). See B(M) below.
......(...)
...3♥+ = A(♠,♣). See A(M,m) below.
3♣ = INV P/C w/ 3-S4-H2+C
...P/3♣ = much as in the OP, but with P replacing 3♣ and 3♠/3N switched. In detail:
...P = non-MAX, 5+ C
...3♦ = non-MAX, 5+ D
...3♥ = non-MAX, 4+ H
...3♠ = MAX, either 5+ m or 4 H
......3N = to play opposite 3- H
.........P = 3- H
.........4♣ = 4441(!) (=> 4N = to play/looking stupid)
.........4♦ = 4450
......(...)
...3N = MAX, 4S5H
...4♣ = 4S6+H
...4♦ = 5S6+H
3♦ = INV, 3-S4-H1-C
...Maybe
...P = non-MAX, 4-H3+D
...3♥ = non-MAX, 5+ H
...3♠ = non-MAX, 4S3-H1-D
...(...)
3♥ = INV, 4+ S
other = as above

2♥-?:

2♠ = as above OR INV, 5+S3-H
...P = 4+ S / ?
...2N = non-MAX, 3- S (=> 3♣ = P/C)
...3♣ = MAX, 5+ C or 1444
...3♦ = MAX, 5+ D
...(...)
2N = INV, unsuitable for 2♠/3♣ / any GF
...3♣ = 5+ D or 1444
......3♦ = relay
.........3♥+ = A(♥,♦). See A(M,m) below.
...3♦ = 4+ S
......3♥ = GF relay, either with 3+ S or slam interest
.........3♠+ = B(♥). See B(M) below.
......3♠ = was INV, 3-4 S, NF
......(...)
...3♥+ = A(♥,♣). See A(M,m) below.
3♣ = INV P/C w/ 4-S3-H2+C
...P/3♣ = much as in the OP, but with P replacing 3♣ and 3♠/3N switched. In detail:
...P = non-MAX, 5+ C
...3♦ = non-MAX, 5+ D
...3♥ = non-MAX, 4+ S
...3♠ = MAX, either 5+ m or 4 S
......3N = to play opposite 3- S
.........P = 3- S
.........4♣ = 4414(!) (=> 4N = to play/looking stupid)
.........4♦ = 4405
......(...)
...3N = MAX, 5S4H
...4♣ = MAX, 6+S4H
...4♦ = MAX, 6+S5+H
...4♥ = MAX, 5S5H
3♦ = INV, 4+ H
other = as above

A(M,m):

3♥ = non-MAX, either 5+ m or, if m=♦, 4M144
...P(M=♥,m=♣) = was INV, 3 H
...3♠ = 5+ OM
......3N = 2- OM
......4♣+ = 3 OM, cue
...(...)
3♠ = MAX, 2-OM5+m
3N = MAX, 3M5+m
4♣(m=♦) = MAX, 4M144

B(M):

Something like

3♠ = MAX, 4 OM
3N = non-MAX, 4 OM
4♣ = MAX, 4M5+OM
4♦ = MAX, 5M5+OM
4♥ = non-MAX, 5+ OM.

100 random deals (and some bidding, using my own 2♣ defence) consistent (modulo finer points of hand evaluation) with North opening a Multi^2 2♣ in 1st seat NV:

Spoiler

n 84.KQ9872.64.T32 e KQJ75.T653.9.954 s A963.A4.Q532.J76 w T2.J.AKJT87.AKQ8

2♣-(P)-2♥-(X*)
P-(2♠)-P-(3♦)
P-(?)

* takeout of H, but 15-17/21+ instead of (18)19+ if BAL w/ 3+ H

n A82.AJT984.874.9 e J654.Q.K653.AT85 s 9.K2.AQJT92.KJ64 w KQT73.7653..Q732

2♣*-(P)-2♦-(P)
2♥-(P)-3♣-(P)
3♥-(P)-P-(P)

* pretending Opener has only 9 hcp

n 98752.98.KQJ75.4 e AKT6.KT52.AT64.2 s J.J.9832.AKQT763 w Q43.AQ7643..J985

2♣-(X*)-XX-(3♦**)
?

* takeout of C, but 15-17/21+ instead of (18)19+ if BAL w/ 3+ C
** INV+ w/ H

n K7643.J65.3.QJ63 e 95.K82.T94.AK974 s AQJT8.943.KQ72.2 w 2.AQT7.AJ865.T85

2♣-(P)-2♥-(P)
2♠-(P)-4♠-(?)

n .A6432.KT5.J9843 e 9842.KQJ5.73.AT7 s AKQ653.7.A9642.6 w JT7.T98.QJ8.KQ52

2♣-(P)-2♦*-(P)
2♠-(P)-P-(P)

* assuming South is not worth an invite

2♣-(P)-2♠**-(P)
3♣-(P)-3♦-(P)
3N-(P)-4♦-(P)
5♦-(P)-P-(P)

** assuming South is worth an invite

n AJT853.9.Q8.9852 e .KQT.AKT63.QJ763 s K764.J8765.J9.K4 w Q92.A432.7542.AT

2♣-(P)-3♠-(P)
4♠-(X)-P-(?)

n 4.JT732.852.J964 e Q73.K9654.J7.A85 s K98652.AQ.KQ963. w AJT.8.AT4.KQT732

2♣-(P)-2♠$-(3♣*)
P-(3♦**)-?

$ assuming the hand is strong enough for an invite
* good C overcall or bad D overcall
** to play opposite the bad D overcall

n 8.KQJT32.K52.863 e K73.A984.T6.AK74 s JT54..AQJ9873.T5 w AQ962.765.4.QJ92

2♣-(X*)-XX-(2♠)
?

* takeout of C, but 15-17/21+ instead of (18)19+ if BAL w/ 3+ C

n KT6543.Q.T83.Q96 e AJ.AK4.A74.A7532 s 82.T9763.QJ.KT84 w Q97.J852.K9652.J

2♣-(X)-P-(2♥)
P-(?)

or

2♣-(X)-P-(2♦)
P-(?)

n 5.87542.JT.AT642 e AKQ87.T6.A9765.3 s T42.KQJ93.Q42.J9 w J963.A.K83.KQ875

2♣-(3♦*)-P-(4♣**)
P-(4♦***)-P-(?)

* very good H overcall or pointeds at least 5-5
** GF relay
*** pointeds at least 5-5

n 2.J8732.K965.JT6 e QJ.AQT.QJ42.AK85 s AK86.K54.83.7432 w T97543.96.AT7.Q9

2♣-(2N*)-P-(?)

* 18-20 BAL

n Q.QJT876.6.J8654 e AJ42.95.AQJ52.T9 s 8753.432.T98.K73 w KT96.AK.K743.AQ2

2♣-(P)-2♥-(2N*)
P-(?)

* 18-20 BAL or bad C overcall

or

2♣-(2♦*)-P-(2N**)
P-(?)

* normal D overcall or bad H overcall
** F1 relay

n .JT753.765.KQJ94 e AKQJ4.Q9.A.T7632 s T962.K42.QT8.A85 w 8753.A86.KJ9432.

2♣-(P)-2♥-(P)
P-(3♦*)-p-(3♥**)
P-(?)

* nominally a good D overcall or blacks at least 5-5
** relay

n 8.QJT73.62.Q9643 e KT.A8542.KT93.J7 s Q97542..AQ54.AT2 w AJ63.K96.J87.K85

2♣-(P)-2♦-(P)
2♠-(X*)-P-(?)

* takeout of S

n K9.QJT96.T642.53 e J854.A4.KJ985.72 s QT73.853.3.QT984 w A62.K72.AQ7.AKJ6

2♣-(P)-2♥-(X)
P-(2♠)-P-(?)

n QJT862.9.843.AT7 e 9.742.QJ76.KQJ52 s A54.KJ86.AT9.986 w K73.AQT53.K52.43

2♣-(P)-2♦-(P)
2♠-(P)-3♥-(P)
3♠-(P)-P-(P)

n KJT85.65.J532.76 e 942.KQJT9843.6.J s 63.72.AQT9.AT532 w AQ7.A.K874.KQ984

2♣-(P)-2♥-(X)
2♠-(?)

n AJ765.6.T5.K9843 e T.AQT874.973.J72 s 832.KJ53.J84.AQ6 w KQ94.92.AKQ62.T5

2♣-(P)-2♦-(X)
2♥-(P)-2♠-(P)
P-(?)

n .87642.Q753.AQ97 e AQJ86.KJT.J6.KT4 s KT932.5.K942.532 w 754.AQ93.AT8.J86

2♣-(X*)-P-(?)

* takeout of C, but with 15-17/21+ instead of (18)19+ if BAL w/ 3+ C

n 94.KQJ863.96.K82 e J3.T54.J7543.943 s 8762.97.AKQ8.AJ7 w AKQT5.A2.T2.QT65

2♣-(P)-2♥-(2♠*)
X$-(P)-2N-(P)
3♥-(P)-?

* normal S overcall or minors at least 5-5
$ takeout ("action" with MAX if weak)

n 9.J8753.5.KJT987 e Q42.64.AQJ632.AQ s J86.AKQT2.K9.542 w AKT753.9.T874.63

2♣-(2♦*)-X-(?)

* normal D overcall or bad H overcall

n 86.KQ9862.8.JT96 e J73.JT5.A963.854 s AKQT2.4.KQT54.AK w 954.A73.J72.Q732

2♣-(P)-2♦-(P)
2♥-(P)-2N-(P)
3♣-(P)-?

n AK964.87.96.Q762 e J53.T43.A432.K54 s T872.AK6.Q5.AJT9 w Q.QJ952.KJT87.83

2♣-(P)-2♥-(P)
2♠-(P)-?

n Q97643.QT7.KJ7.8 e 5.AK6.8653.KQ742 s A.8542.A42.AJT65 w KJT82.J93.QT9.93

2♣-(P)-2♦-(P)
2♠-(X)-P-(P)
P

n KT.QJ643.6543.J4 e AQJ83.T98.AJ8.K5 s 972.52..AQT98762 w 654.AK7.KQT972.3

2♣-(X*)-XX-(3♣**)

takeout of C, but 15-17/21+ instead of (18)19+ if BAL w/ 3+ C
** INV+ w/ D

n QJ865..AT9852.62 e AKT72.J8.K7.AJT7 s .A7643.3.KQ98543 w 943.KQT952.QJ64.

2♣-(X*)-XX-(3♦**)
?

* takeout of C, but 15-17/21+ instead of (18)19+ if BAL w/ 3+ C
** INV+ w/ H

n 3.AK752.764.T964 e J92.4.Q9832.AJ83 s QT8764.T9.KT5.Q5 w AK5.QJ863.AJ.K72

2♣-(P)-2♦-(2N*)
P-(3♣**)-P-(?)

* 18-20 BAL or bad C overcall
** to play opposite the bad C overcall

or

2♣-(P)-2♥-(2N*)
P-(3♣**)-P-(?)

* 18-20 BAL or bad C overcall
** to play opposite the bad C overcall

n J9873.6.QT654.J3 e KQ62.A742.832.52 s AT5.QJT5.AK9.KQ9 w 4.K983.J7.AT8764

2♣-(P)-2♦-(P)
2♥-(P)-2N-(P)
3♦-(P)-4♠-(P)
P

n KQ965.T85.K.9865 e J8.A632.82.AKJ42 s AT4.K94.J976.Q73 w 732.QJ7.AQT543.T

2♣-(P)-2♦-(P)
2♥-(P)-2♠-(P)
P-(?)

or

2♣-(P)-2♥-(P)
2♠-(X)-P-(?)

n KQ9873.J5.J8.JT2 e T42.94.KQT654.A6 s 5.AT863.A9.Q9853 w AJ6.KQ72.732.K74

2♣-(P)-2♦-(P)
2♠-(?)

n AJ865.T.QJ65.J74 e Q32.AK83.A832.32 s 9.QJ752.K974.KT6 w KT74.964.T.AQ985

2♣-(X*)-P-(P)
2♦-(P)-p-(?)

* takeout of C, but with 15-17/21+ instead of (18)19+ if BAL w/ 3+ C

n A98754.JT.Q764.T e J.43.AJ982.K9752 s Q62.KQ875.T.AQJ6 w KT3.A962.K53.843

2♣-(P)-2♦-(P)
2♠-(P)-2N-(P)
3♣-(P)-3♦-(P)
3N-(P)-4♠-(P)
P-(P)

n A8763.K5.53.J762 e KJT2.Q972.AKQ.K3 s 9.JT864.J764.QT5 w Q54.A3.T982.A984

2♣-(X*)-P-(2♦)
P-(2♥**)-P-(?)

* takeout of C, but with 15-17/21+ instead of (18)19+ if BAL w/ 3+ C
** frequently 15-17 BAL w/ 4-5 H

n AT65432.64.T.963 e QJ9.Q53.Q62.QT84 s K.AJ98.A753.AJ52 w 87.KT72.KJ984.K7

2♣-(P)-2♦-(P)
2♠-(P)-2N-(P)
3♣-(P)-3♦-(X)
?

n 7.Q9865.QT63.QT6 e J642.7.AKJ9874.9 s A85.AKJ42..AJ852 w KQT93.T3.52.K743

2♣-(2♦*)-X$-(2♥**)
P-(2♠)-?

* normal D overcall or bad H overcall
** to play opposite the bad H overcall
$ takeout of D, but 15-17/21+ if BAL w/3+ D

n 92.Q9763.9.KT762 e Q763.2.AJT542.Q3 s JT4.AKT54.83.A95 w AK85.J8.KQ76.J84

2♣-(P)-2♦-(P)
2♠-(P)-3♠-(P)
4♣-(P)-4♥-(?)

n 6.QJT987.8632.72 e Q52.K65.J.J98543 s AKJT843.32.AQ9.6 w 97.A4.KT754.AKQT

2♣-(P)-2♠-(X*)
2N-(?)

* takeout of S, but with 15-17/21+ instead of (18)19+ if BAL w/ 3+ S

n A9763.43.Q765.76 e KQJ852.Q5.AT4.J2 s T.K97.J83.AKT853 w 4.AJT862.K92.Q94

2♣-(2♥*)-2N$-(P)
3♣$$-(?)

* good H overcall or bad S overcall
$ 18-20 BAL or bad C "overcall" (ignoring the opening)
$$ to play opposite the bad C "ovvercall"

n 9.KJT84.A87.T954 e J87643.972.2.J83 s KT5.653.KJ963.AQ w AQ2.AQ.QT54.K762

2♣-(P)-2♥-(X*)
P-(2♠)-P-(2N**)
P-(3♠)-P-(P)
P

* takeout of H, but 15-17/21+ instead of (18)19+ if BAL w/ 3+ H
** 15-17 BAL, 2-3 S

or

2♣-(P)-2♦-(X*)
2♠-(P)-3♥-(?)

* takeout of D, but 15-17/21+ instead of (18)19+ if BAL w/ 3+ D

n KQ732.6.J53.J954 e AJ8.72.AK.AQT632 s T64.AKJT43.Q97.7 w 95.Q985.T8642.K8

2♣-(2N*)-P-(3♣)
P-(?)

* 18-20 BAL

n Q7652.QT3.JT543. e K4.J98764.A8.K54 s AJ.A52.Q972.AQ62 w T983.K.K6.JT9873

2♣-(2♦*)-X$-(2♥**)
?

* normal D overcall or bad H overcall
** t0 play opposite a bad H overcall
$ takeout of D, but 15-17/21+ if BAL w/ 3+ D [I used to play the double as "system on", so this is very different]

n 83.KQJ986.Q92.T8 e KQT72.3.K763.AQ5 s 95.4.AJ84.KJ9432 w AJ64.AT752.T5.76

2♣-(P)-2♦-(P)
2♥-(2♠)-P-(?)

n 5.AT985.JT765.54 e AQ3.764.AQ.AQJ96 s 98642.KQ3.983.73 w KJT7.J2.K42.KT82

2♣-(2N*)-P-(?)

* 18-20 BAL

n KJT753.62.72.QJ6 e 842.J8.AK64.K874 s Q.K9753.J83.AT52 w A96.AQT4.QT95.93

2♣-(P)-2♦-(P)
2♠-(P)-P-(P)

n A.AKQJ95.KQ3.AT7 e QJT5.6.AT9875.98 s K96.T842.J2.KJ65 w 87432.73.64.Q432

2♣-(P)-2♦-P
2N etc.

* strong (meets the rule of 31): either 5+H4+C (not 5H5C) or 1-suited w/ 6+ H

n 74.T9865.KJ.QJ43 e KT8.QJ73.AT95.T7 s AJ632.K2.3.A9865 w Q95.A4.Q87642.K2

2♣-(P)-2♥-(3♣*)
P-(3♦**)-?

* good C overcall or bad D overcall
** to play opposite the bad D overcall

n AQJ76.8.T5432.J6 e 2.AQT64.KJ7.Q953 s T954.KJ9532.Q98. w K83.7.A6.AKT8742

2♣-(P)-4♦-(?)

n JT9752.KT.KT7.76 e Q43.752.A86.QJT3 s 86.Q43.Q932.A842 w AK.AJ986.J54.K95

2♣-(P)-2♠-(X*)
P-(?)

* takeout of S, but with 15-17/21+ instead of (18)19+ if BAL w/ 3+ S

n AQ5.T9642.K972.6 e KT863.A53.43.J32 s J974.7.AQT.AKQ85 w 2.KQJ8.J865.T974

2♣-(P)-2♦-(P)
2♠-(P)-2N-(P)
3N-(P)-P-(P)

n J.T987643.854.T9 e A96.Q52.AT9.KJ65 s T7432.AK.K7.Q872 w KQ85.J.QJ632.A43

2♣-(P)-2♥-(X*)
?

* takeout of H, but with 15-17/21+ instead of (18)19+ if BAL w/ 3+ H

n JT8532.J.J52.Q98 e 7.AK976.A974.AT5 s AKQ.3.KT863.K763 w 964.QT8542.Q.J42

2♣-(P)-2♦-(P)
2♠-(X*)-3♣-(?)

* takeout of S

n 94.A9763.64.KT54 e A7653.J82.53.Q63 s J2.5.AQJ982.9872 w KQT8.KQT4.KT7.AJ

2♣-(P)-2♦-(2N*)
P-(3♣**)-P-(?)

* 18-20 BAL or bad C overcall
** to play opposite the bad C overcall

n K8.AJT87.T9.T975 e 743.K43.A754.J63 s JT95.Q95.KQ3.K82 w AQ62.62.J862.AQ4

2♣-(P)-2♥-(X*)
P-(2N**)-P-(3♣***)
P-(3♦****)-P-(P)
P

* takeout of H, but with 15-17/21+ instead of (18)19+ if BAL w/ 3+ H
** lebensoholish, but Advancer may pass with 15-17 BAL and no good bid
*** as in standard lebensohl
**** to play

n KT843.Q73.J954.3 e 5.AJT9.A32.A9865 s .K86542.T8.KQJ74 w AQJ9762..KQ76.T2

2♣-(P)-2♦-(2♠*)
P-(?)

* good S overcall or pointeds at least 5-5

n QJT52.AT5.9.7432 e 9863.843.KQJ74.A s A4.Q972.AT5.KJ85 w K7.KJ6.8632.QT96

2♣-(P)-2♠-(P)
P-(P)

n 7.AT832.854.JT92 e J5.974.962.Q8743 s AT842.65.AKQT.A5 w KQ963.KQJ.J73.K6

2♣-(P)-2♠-(P)
2N-(P)-3♦-(P)
P-(P)

n 5.QJT865.9764.T3 e QJT972.42.AT.K54 s K43.AK9.QJ5.AJ92 w A86.73.K832.Q876

2♣-(P)-2♦-(P)
2♥-(?)

n 7.KQJ54.982.KT97 e KJT8.973.AQJT5.J s AQ932.82.K73.863 w 654.AT6.64.AQ542

2♣-(X*)-2♥-(P)
P-(P)

* takeout of C, but with 15-17/21+ instead of (18)19+ if BAL w/ 3+ C

n 98765.K3.K864.T5 e Q2.JT984.AJ973.2 s K43.Q75.T.AQJ743 w AJT.A62.Q52.K986

2♣-(P)-2♦-(P)
2♥-(P)-2♠-(P)
P-(P)

or

2♣-(P)-2♥-(P)
2♠-(P)-P-(P)

n T3.Q6432.A8.T954 e 87542.AK7.QJ96.8 s AKJ6.J95.T72.J32 w Q9.T8.K543.AKQ76

2♣-(P)-2♥-(X*)
P-(3[di**)-P-(?)

* takeout of H, but with 15-17/21+ instead of (18)19+ if BAL w/ 3+ H (here treating 2245 as worth an extra point (rightly or wrongly))
** INV+, 5+ S

n AJ864.742.Q.Q632 e 97.KT95.T32.KJ95 s KQ32.J3.K875.AT8 w T5.AQ86.AJ964.74

2♣-(P)-2♥-(P)
2♠-(P)-3♠-(P)
P

n Q.K9864.QT64.Q32 e 9862.JT32.3.AK64 s JT53.5.KJ972.987 w AK74.AQ7.A85.JT5

2♣-(P)-2♦-(2N*)

* 18-20 BAL or bad C overcall

n J65.T8763..KQ872 e AQ3.KQ5.AJ8.AJ54 s 742.J2.7632.T963 w KT98.A94.KQT954.

2♣-(X*)-P-(3♣**)
?

* takeout of C, but with 15-17/21+ instead of (18)19+ if BAL w/ 3+ C
** INV+ w/ D

n KQ942.32.T832.T2 e 753.JT8.KJ96.Q85 s JT8.K965.A5.AJ74 w A6.AQ74.Q74.K963

2♣-(P)-2♦-(X*)
P$-(P)-XX$$-(P)
2♥$$$-(P)-2♠$$$$-(?)

* takeout of D, but with 15-17/21+ instead of (18)19+ if BAL
$ weak, 4+ D
$$ re-ask
$$$ 6(+) H or 5 S
$$$$ P/C

n JT964.AT3..T9654 e AQ85.Q7.AK9875.K s 73.KJ8654.T43.87 w K2.92.QJ62.AQJ32

2♣-(X*)-XX-(P)
2♦-(P)-2♥-(?)

* takeout of C, but with 15-17/21+ instead of (18)19+ if BAL w/ 3+ C

n KJ8763.Q8.432.T7 e AQT4.52.J.AKQ943 s 952.764.AQ87.862 w .AKJT93.KT965.J5

2♣-(P)-2♥-(P)
?

n 952.T98542.Q72.5 e AKT74.AQ7.T.J743 s QJ8.K63.A8543.KT w 63.J.KJ96.AQ9862

2♣-(P)-2♥-(2N*)
P-(?)

* 18-20 BAL or bad C overcall

n .QT642.J54.A5432 e KQT72.K98.AT76.T s A9543.5.K98.Q876 w J86.AJ73.Q32.KJ9

2♣-(X*)-P-(2N**)
P-(3♣)-P-(?)

* takeout of C, but with 15-17/21+ instead of (18)19+ if BAL w/ 3+ C
** puppet to 3♣

n 97653.7.JT865.T8 e AQ4.Q82.K3.KQ965 s KJT.JT653.Q2.J32 w 82.AK94.A974.A74

2♣-(X*)-2♦-(?)

* takeout of C, but 15-17/21+ instead of (18)19+ if BAL w/ 3+ C

n KT942.953.J875.Q e AJ65.K42.9.J6542 s .T7.AKQT643.AT93 w Q873.AQJ86.2.K87

2♣-(P)-2♦-(X*)
P$-(2♠)-?

* takeout of D, but 15-17/21+ instead of (18)19+ if BAL w/ 3+ D
$ weak, 4+ D

n A9752.J4.T863.83 e 6.KQ932.AQJ5.KJ6 s JT843..K74.Q7542 w KQ.AT8765.92.AT9

2♣-(P)-2♦-(2♥*)
P-(?)

* normal H overcall or bad S overcall

n AJ764.Q8.97.J643 e QT2.A2.K83.AKQ87 s 85.K6543.6542.92 w K93.JT97.AQJT.T5

2♣-(2N*)-P-(?)

* 18-20 BAL

n K97.AJ8642.765.J e A85.QT95.KT.T952 s QT643..AJ98.K874 w J2.K73.Q432.AQ63

2♣-(P)-2♦-(P)
2♥-(P)-P-(P)

n QT8765.42.KQ8.52 e 94.J9863.J6.AJ86 s AK32.KQ7.9732.43 w J.AT5.AT54.KQT97

2♣-(P)-2♥-(P)
?

n T54.J9542.JT63.7 e A963.876.A2.JT42 s Q87.K3.K754.AK93 w KJ2.AQT.Q98.Q865

2♣-(P)-2♥-(P)
P-(P)

n Q9865.A5.T8.Q872 e AKJ7.KJ2.652.AJT s 3.QT9843.AKJ.963 w T42.76.Q9743.K54

2♣-(X*)-XX-(2♦)
P-(?)

* takeout of C, but with 15-17/21+ instead of (18)19+ if BAL w/ 3+ C

n 97.A9652.96542.5 e AK3.K43.AKJ.Q983 s QJ8652.T.87.J762 w T4.QJ87.QT3.AKT4

2♣-(2N*)-P-(?)

* 18-20 BAL

n 875432.T3.AK64.T e QT6.K8542.J8.KQ9 s .J976.QT532.8754 w AKJ9.AQ.97.AJ632

2♣-(P)-2♦-(2N*)
P-(3♣**)-P-(?)

* 18-20 BAL or bad C overcall
** to play opposite the bad C overcall

n K9632.Q9.J.T9743 e QT.8632.Q73.AK65 s J5.AT.AKT654.QJ8 w A874.KJ754.982.2

2♣-(P)-2♥-(P)
2♠-(P)-P-(P)

n 76543.T73.4.KT87 e AJ2.6542.965.Q65 s Q8.KJ.AQ732.J943 w KT9.AQ98.KJT8.A2

2♣-(P)-2♥-(2N*)
P-(3♣**)-P-(?)

* 18-20 BAL or bad C overcall
** to play opposite the bad C overcall

n 3.QT972.J9854.K4 e J942.J86.3.AQT65 s KQ6.4.AKQT.J9872 w AT875.AK53.762.3

2♣-(P)-2♦-(P)
2♠-(P)-3♣-(?)

n .AJ9842.Q763.732 e T872.T7653.AK82. s AQJ653.KQ..AJ865 w K94..JT954.KQT94

2♣-(P)-2♦*-(P)
2♥-(P)-2N-(P)
3♣-(P)-?

* assuming the hand is worth more than an invite

n 9.87652.A762.A52 e AQ63.9.KJ53.QJ76 s K7542.J43.QT.T43 w JT8.AKQT.984.K98

2♣-(P)-2♥-(P)
P-(X)-P-(?)

n 86.A5432.Q6.KT86 e KJ3.JT8.J52.AQ42 s AQ975.76.T43.J75 w T42.KQ9.AK987.93

2♣-(P)-2♥-(P)
P-(P)

n 6.JT876.T8532.95 e KT85.AK9.Q76.A82 s Q7432.Q52.KJ9.JT w AJ9.43.A4.KQ7643

2♣-(X*)-2♥-(?)

* takeout of C, but with 15-17/21+ instead of (18)19+ if BAL w/ 3+ C

n JT986.A75.QJ98.9 e 74.KQ643.642.Q62 s Q5.T9.KT73.KT873 w AK32.J82.A5.AJ54

2♣-(P)-2♥-(2N*)
P-(3♣**)-P-(?)

* 18-20 BAL or bad C overcall
** to play opposite the bad C overcall

n QJT9753.J76.T.T8 e 6.KQT8.AKJ432.54 s A82.A954.5.KQJ97 w K4.32.Q9876.A632

2♣-(2♦*)-X-(2♥**)
?

* normal D overcall or bad D overcall
** to play opposite the bad H overcall

n 963.Q98652.T4.Q4 e J82.KJ3.A92.T853 s Q5.AT74.Q763.KJ7 w AKT74..KJ85.A962

2♣-(P)-2♠-(P)
2N-(P)-3♥-(?)

n A42.T65432.5.KT3 e 9876.J9.KQT762.J s KQJT3.AQ8.A9.A94 w 5.K7.J843.Q87652

2♣-(P)-2♦-(P)
2♥-(P)-2N-(P)
3♣-(P)-3♦-(P)
3N-(P)-?

n 4.T986532.7.Q984 e T9762.J7.A652.72 s QJ85.AQ.KQ94.AJT w AK3.K4.JT83.K653

2♣-(P)-2♦-(P)
2♥-(P)-2N-(P)
3♣-(P)-3♦-(P)
?

n QJ754.T73.K.QJT4 e T86.962.T8732.95 s 9.KQ5.Q654.A8732 w AK32.AJ84.AJ9.K6

2♣-(P)-2♦-(X*)
2♥-(P)-2♠-(?)

* takeout of D, but 15-17/21+ instead of (18)19+ if BAL w/ 3+ D

n 6.AJ843.942.KJ64 e KJT542.Q6.KJ63.Q s AQ83.T75.QT.T985 w 97.K92.A875.A732

2♣-(2♥*)-P-(?)

* good H overcall or bad S overcall

n AK9.Q97642.T76.T e JT543.85.QJ82.84 s 7.AKJT.A954.AKQ2 w Q862.3.K3.J97653

2♣-(P)-2♦-(P)
2♥-(P)-2N-(P)
3♣-(P)-3♦-(P)
3N-(P)-?

n J.QT954.K973.Q94 e KQT85432.6.T6.T6 s 96.K3.QJ82.AKJ72 w A7.AJ872.A54.853

2♣-(P)-2♥-(P)
P-(?)

n AT2.KT7542.953.4 e KQ.9863.A87.QJT7 s J97653.Q.J4.K962 w 84.AJ.KQT62.A853

2♣-(P)-2♦-(X*)
2♥-(?)

* takeout of D, but 15-17/21+ instead of (18)19+ if BAL w/ 3+ D

n T3.KJT982.K73.T8 e KQJ98.AQ.AJ86.62 s A764.6.QT542.KJ4 w 52.7543.9.AQ9753

2♣-(2N*)-P-(3♣)
P-(3♠)-P-(3N)
P-(P)-P

* 18-20 BAL

n 3.KQT963.A62.982 e QJT962.J7.T985.6 s 74.A542.K7.KQT73 w AK85.8.QJ43.AJ54

2♣-(P)-2♠-(P)
3♥-(P)-4♥-(?)

n K97654.4.643.QJ9 e J83.KQ9873.QJ92. s 2.A652.K875.AK87 w AQT.JT.AT.T65432

2♣-(P)-2♦-(2N*)
P-(3♣**)-P-(P)
P

* 18-20 BAL or bad C overcall
** to play opposite the bad C overcall

n KQT643.T.QT7.T54 e A75.Q9642.J3.A73 s J98.AK5.AK65.Q96 w 2.J873.9842.KJ82

2♣-(P)-2♦-(P)
2♠-(P)-2N-(P)
3♣-(P)-3♦-(P)
3N-(P)-?

n KQT542.653.3.987 e A73.J984.842.AK5 s .AK7.AQT9765.J64 w J986.QT2.KJ.QT32

2♣-(P)-2♦-(P)
2♠-(P)-P-(P)

(Not good, but I haven't defined 2♣-3♦ and 2♣-2♦; 2M-3♦ yet. )

Generated 1426 hands
Produced 100 hands

[nullve]

gwnn has repeatedly been talking about or alluding to the (very real, but possibly exaggerated) danger of ending up in non-fit after 2C-2D; 2M-P when Responder has 1M3OM (a case of small length disparity between Responder's majors). To keep things straight, let me just point out that 1M3OM is conceivably a serious problem only if Responder has about 8-15 hcp and either 1M3OM(54) or 1M3OM(63).

Reason: If Responder has

* 0-7 hcp, then 2M on a non-fit ought to be good, since opps will have 24+ hcp between them.
* 16+ hcp, he will be able to continue with 2N (inv+ relay) over 2C-2D; 2M
* 15- hcp, 1M3OM7+m, he'll be determined to play 3m, anyway, and may therefore not have responded 2D in the first place.

Even 8-15 hcp, 1M3OM36 may not be be a serious problem, since Responder always had the option to pass 2C. (Yes, I forgot to list Pass as a possible response to 2C.) A good reason for doing that (apart from avoiding non-fits, if that seems like a good reason) is that he may not be happy to play 3D on a likely 4-3 fit after 2C-2D; 2OM(6 OM or 5M4+m)-3C(P/C); 3D(5M4+D)-P. Similarly, with 8-15 hcp, 1M3OM63, Responder would rather avoid playing 3C on a likely 4-3 fit after 2C-2D; 2OM-3C; P(5S4+C), but what can he do? I can imagine creative attempts/systemic alternatives such as

2C-2H(P/C, usually with [edit:] 2+S2H or 3+S3H); 2S-3D(to play with 1363?)
2C-2S(P/C, usually 2S3+H); 2N(6H3-D3-C?)-3D(to play with 3163?),

which I believe is similar to what helene_t suggested early in this thread, but for now, let's just say that with 8-15 hcp, 1M3OM63 may be more of a problem than 1M3OM36.

[Free]

Must be fun to play multi vs mushroom: 2♦ = I also have a long Major. Bye bye continuations for opps