[nullve]

Multi Squared

2C = Multi: 6M or 5M4+m / strong options according to taste

2C-?:

2D = relay, usually with inv+ values or a potentially misfitting hand

2M = Multi*: 6 M or 5OM4+m

P = allowed, usually with 1- M (assuming p has 6 M) or (5)6+ M (assuming p has 5OM4+m)

2S = P/C

2N = inv+ relay

3m = non-max, 5OM4+m

3M = min, 6 M

3OM = max, 6 M

3N = max, 5OM4+m

3C = P/C

2N+ = strong options, if desired

2H = P/C, usually 2+S2H or 3+S3H
2S = P/C, usually 2S3+H
2N+ = possibly depending on whether 2C is "weak-only" or not. If strong balanced hands are included, I like to play
2N = PRE w/ long minor or inv w/ long major

3C+ = P/C

3C = < inv opposite weak hands, GF opposite bal hands, 5+M4+OM

3D = strong balanced, relay

3H+ = Smolen

3D = < inv opposite weak hands, GF opposite bal hands, 4S4H
3M = nat PRE (not P/C!)

* and Multi followed by Multi is Multi^2


MuSHroom

(1N)-?:

X = cards
2C = Multi Squared
2D = S anchor suit, uknown canapé (4-4 possible, especially with 44(41) shape)

2H = P/C

2S = to play

2N = inv+ relay

3m = non-max, 5+ m

3H = non-max, 5+ H

3S = max, 5+ H

3N = max, 5+ m

3C = P/C

3S = PRE

2H = H anchor suit, uknown canapé

2S = P/C

2N = inv+ relay

3m = non-max, 5+ m

3H = non-max, 5+ S

3S = max, 5+ S

3N = max, 5+ m

3C = P/C

3H = PRE

2S+ = room for something else


Preempt-Preparatory Pass (1st seat NV only)

P = less than opening strength, no singleton or void, unsuitable for preemption

I call this pass 'preempt-preparatory' because it prepares the ground for wild-looking but still reasonably safe preempts by 3rd hand. The idea is to play it in conjunction with a MuSHroom-like scheme of preempts that takes care of all hands with less than opening strength that contain a singleton or void. E.g.

P = preempt-prepartory
2C+ = MuSHroom-like preempts (2C and 2D possibly containing strong options) where e.g.
2S = 5+m4+Om (as in Big Bang)
2N = whatever
3C+ = normal aggressive preempts (but 3m is mandatory with 6m(331))

Added, starting 20 January 2017:

Spoiler

20.01.17: For a more detailed example, here's what I'd like to play in 1st seat NV:

Rough description:

P = "0-10 bal."
1♣ = "(quasi)nat. unbal. or 14-19/26+ bal, F1
1♦ = "(quasi)nat. unbal. or 20-22 bal., F1
1M = "5+ M, unbal."
1N = "11-13 bal."
2♣ = "0-9, either 6(+) M or 5M4+m" / "GF, 5+ H, unbal."
2♦ = "0-9(10)", either 4S4D(41), 4S5+m or 4+S5+H / GF, 5+ S, unbal."
2♥ = "0-9(10)", either 4H4C(41), 4H5+m or 5+S4+H"
2♠ = "0-6", C preempt / "7-9, 5+m4+Om"
2N = "0-6, either 5+m4+m or D preempt" / 23-25 bal.
3♣ = 7-9, 6 C, 1-suited
3♦ = 7-9, 6 D, 1-suited
3M = "6-8(9)", 7 M"
3N = "5-7(8)", unknown 8c suit, 1-suited [just an idea so far]
4m = "6-8(9)", 7 m, 1-suited
(...)

In more detail:

P = 0-9, either 5m(422) (then mandatory only with 22(54))) or 6m(322) (then not mandatory) / 0-10, either bal. or (4441) w/ singleton A/K/Q
1♣ = rule of 19+," nat. unbal.", but including rules of 19-24, 3154/4054/4144/4153 and excluding rules of 19-24, 0445/1345/1435/1444 / "14-19/26+ bal."
1♦ = rule of 19+, "nat. unbal.", but including rules of 19-24, 0445/1345/1435/1444 and excluding rules of 19-24, 3154/4054/4144/4153 / "20-22 bal."
1M = rules of 19-30, "5+ M, unbal."
1N = "11-13 bal."
2♣ = rules of 9-15, 7+M3-OM / rules of 9-18, either 5M3-OM4+m or 6M3-OM / rule of 31+, "5+ H, unbal."
2♦ = rules of 9-18, either 4S4D(41), 4M5+m or 4+S5+H / rule of 31+, "5+ S, unbal."
2♥ = rules of 9-18, either 4H4C(41), 4H5+m or 5+S4+H
2♠ = rules of 9-15, 3-S3-H4-D6+C (but not mandatory with 6C(322)) / rules of 16-18, either (31)(54), 5D5C or 6+m4+Om
...(...)
...2N = D pref. or no pref. opposite 5m4Om / INV
......P(!) = rules of 9-15
......3♣ = rules of 16-18, D not longer than C
.........P = was no pref. opposite 5m4Om
.........3♦ = to play, was D pref. opposite 5m4Om
.........(...)
......3♦ = rules of 16-18, D longer than C
...3♣ = C pref. opposite 5m4Om, no game interest
...3♦ = GF relay
...(...)
2N = rules of 9-15, either (31)(54), 5+D5+C or 3-S3-H6+D (but not mandatory with 6D(322)) / 23-25 bal.
...Responses are two-way in the sense that Responder With 0-9(?)/10(?)+ hcp will bid as if Opener has 23-25 bal./0-6, either 5+m4+Om or 6 D, respectively. With 10(?)+ hcp the responses are:
...P = often for tactical reason (e.g. without clear pref. opposite 5m4Om or in order to explore major suit fits if Advancer doubles!)
...3♣ = C pref. opposite 5m4Om, no game interest
......P = 4+ C
......3♦ = D 1-suiter
...3♦ = D pref. opposite 5m4Om, no game interest
...3♥ = GF relay
...(...)
3♣ = rules of 16-18, either 6C(322) (then not mandatory) or 6C(331) (then mandatory)
3♦ = rules of 16-18, either 6D(322) (then not mandatory) or 6D(331) (then mandatory)
3M = rules of 16-18, 7M3-OM
3N = rules of 16-18, unknown 8c suit, 1-suited [just an idea so far]
4m = rules of 16-18, 7 m, 1-suited
(...)

[scheme updated 13 Jun 2017]

There are some very interesting runout possibilites after 2N-(X) and 2N-(P)-P-(X) (and 2♠-(X) and 2♠-(P)-2N-(X), for that matter), but I won't go into details here.

[14 Jun 2017: Yes, I will:

2N-(P)-P-(X); ?:

P = 3 H
...XX = relay
......3♣ = 5 C (so 0355 or 1345)
......3♦ = 5+D4-C (so 1354 or 3H6+D)
...(...)
XX = (21)55 or 2-S2-H6+D
...3♣ = pref. opposite 5D5C
......P = (21)55
......3D = 2-S2-H6+D
...3♦ = pref. opposite 5D5C
......P = forced
...(...)
3♣ = 3S2-H5C (so 3145 or 3055)
3♦ = 3S5+D4-C (so 3154 or 3S6+D)

2N-(X)-?:

P = 5+ H or no clear pref. opposite 5m4Om
...XX = 3 H
......3♣ = 4- H, no pref. opposite 5m4Om
.........P = 5 C (so 0355 or 1345)
.........3♦ = 5+ D (so 1354 or 3H6+D)
...3♣ = 2-H5+C, D not longer than C (so 3145 or 2-H5D5+C)
...3♦ = 2-H5+D, D longer than C (so 3154 or 2-H6+D)
XX = clear pref. opposite 5+m4+Om or long M
...3♣ = 5+m4+Om
......P = C pref.
......3♦ = D pref.
......3M = long M, to play
...3♦ = 6+ D, 1-suited
......P = had clear pref. opposite 5+m4+Om, can't raise preemptively
......3M = long M, to play
......(...)
3♣ = 5+ S, C pref. opposite 5m4Om
...P = 2-S4+C (so 13(54) or 5+D5+C)
...3♦ = 2-S6+D4-C
3♦ = 5+ S, D pref. opposite 5m4Om
...P = 2- S
3♥ = 5+S5+H
(...)]

[3 September 2018: If the bad C preempt in 2♠ is only made with 6+C3M(31) or 6+C3M22, then it's possible to play

2♠-(P)-2N-(X); ?:

P = bad C preempt, 3 H
...P = possible, I guess
...XX = 5+ S
......3♣ = 2- S
......3♠ = 3 S (so 3316)
...3♣ = to play
...3♥ = 5+ H, to play
...other = ?
XX = bad C preempt, 3S2-H
...P = possible, I guess
...3♣ = to play
...3♠ = 5+ S, to play
...other = ?
3♣+: same as over 2♠-(P)-2N-(P).]

I've also been toying with a Mosca-like structure with Mushroom-like 2-openings but without the preempt-preparatory pass.

P = as in Mosca (Fantunes), i.e. not "preempt-preparatory"
1♣ = rule of 22+, nat. unbal. / "14+ bal."
1♦ = rule of 22+, nat. unbal.
1M = rules of 22+, nat. unbal.
1N = "11-13 bal. or 44(41)" (also with all 10-12, 5m(422) or 6m(322))
2♣+ = "Amanita muscaria". In some detail, but not cast in stone yet:
2♣ = rules of 19-21, 6+M4-OM4+m, 5M3-OM4+m or 5S5H
...P: allowed
...2♦ = relay
......2M = as above, but not 5-5
......2N = 5M5D (=> 3♣ = GF relay (=> 3♦ = 5 H; 3♥ = 5 S))
......3♣ = 5M5C (=> 3♦ = GF relay (=> 3♥ = 5 S; 3♠ = 2-S5H; 3N = 3505))
......3♦ = 5S5H (=> 3M = to play)
...(...)
2♦ = rules of 19-21, either 4144, 4S5m(31)/(40), 4S5+H, 4S6+m or 5+S6+H
2♥ = rules of 19-21, either 1444, 4H5m(31)/(40), 5+S4H, 4H6+m or 6+S5+H
2♠ = rules of 19-21, either (31)(54), 5D5C or 6+m4+Om
2N = 10-12, 6m(331)¹
3N = rules of 19-21, 7+ m, 1-suited²
other = standard preempts

¹ Not a brown sticker, since it promises at least average values.
² Does not guarantee "average" values, so all these hands can't be in 2N without making it a brown sticker.

[Zelandakh]

Seems horrible. What are the advantages you are experiencing at the table?

[nullve]

It's not easy to answer your question, because I've only played the 2C opening at the table. I could still describe what I perceive to be the practical advantages of Multi Squared over a similarly defined Garbage Multi 2D, but I strongly suspect you find the "Multi" 2M rebid, which is in fact the key ingredient of Multi Squared, particularly revolting. (Correct me if I'm wrong.) I'm not completely inventing the wheel, though, because a similar 2H bid was used as an opening preempt by e.g. Helgemo-Helness

(http://info.ecatsbri...0BS%20Forms.pdf)

and Versace-Lauria

(http://info.ecatsbri...0bs%20forms.pdf)

in the 2003 Bermuda Bowl. Multi-like 2M opening bids are also part of other (brown sticker) conventions described on Chris Ryall's homepage (http://www.chrisryal...k.two/brown.htm).

[steve2005]

There is a convention with 2♣ as a weak 2♦ or strong hand. This has obvious advantages and not too many disadvantages.

Using as a weak 2M I can see but throwing another weak hand; bidding in competition will just be random. Many people using a Multi-2♦ have gotten rid of the strong component so that with a known fit they can raise high. You cant raise if partner might have a strong ♦ hand or something else

[WGF_Flame]

i think you dont have enough to justify taking the bid one level lower.
you also take out multi nicest point which is having your first bid as p/c
to make it playable you need to change the hand types of 2C inorder to get more of your 2M rebid (maybe both majors hands ?), and maybe even add some hands that would pass 2D response.

if on the table you will get enough sequences of 2C-2D-2H and maybe some 2C-2D-p then you will rock.

[nullve]

steve2005, on 2015-July-15, 11:38, said:

There is a convention with 2♣ as a weak 2♦ or strong hand. This has obvious advantages and not too many disadvantages.

Using as a weak 2M I can see but throwing another weak hand; bidding in competition will just be random. Many people using a Multi-2♦ have gotten rid of the strong component so that with a known fit they can raise high. You cant raise if partner might have a strong ♦ hand or something else

The 2C convention you describe - and you're probably right about its advantages/disadvantages - is just one just one of several conventions sometimes referred to as 'Multi 2C'. But it's not in any way just a 2C version of Multi 2D, and this is why I thought I had to come up with a different name for my own gadget, although it's both similarly defined and has the same status according to WBF regulations as Multi 2D. Just to repeat:

2C = 6 M or 5M4+m [6-card major or (5-card major and 4-card or longer minor)] / [zero or more] strong options according to taste

If you just look at the definition, there's really nothing special about it, except that the opening is 2C, not 2D. If you think it's too loosely defined (compared with tradtional Multi), please have in mind that some pairs even open Multi 2D with 5M(332) as well as with 6M or 5M4+m. So Multi Squared is a kind of "semi-disciplined" Multi, and will also behave like one in competition. (And if opps overcall 2H or higher, it will no longer matter if the opening was 2C or 2D.)

Again, the key ingredient is the 2M rebid, not the 2C opening itself.

[nullve]

WGF_Flame, on 2015-July-15, 12:25, said:

i think you dont have enough to justify taking the bid one level lower.
you also take out multi nicest point which is having your first bid as p/c
to make it playable you need to change the hand types of 2C inorder to get more of your 2M rebid (maybe both majors hands ?), and maybe even add some hands that would pass 2D response.

My intention has always been to use the exact same P/C bids as Multi 2D. So the 2H and 2S responses are P/C, and in a weak-only version I would also use 3H and 3S as P/C.

The 2D response does not even exist in Multi 2D. In Multi Squared it not only wholly replaces the inv+ 2N relay in Multi 2D but is also used on potentially misfitting hands as an aid to better partscore bidding.

[Zelandakh]

nullve, on 2015-July-15, 11:23, said:

a similar 2H bid was used as an opening preempt by e.g. Helgemo-Helness

Perhaps this would be a good moment to reflect on the differences between an opening bid where no other player has shown strength and a rebid where partner has shown strength and both opponents have passed. The multi 2♥ opening you mention is quite popular amongst some of the BBF posters and well known to the majority here.

[gwnn]

2H multi is one of the best conventions in bridge (when NV). Here you eliminate almost all the havoc wreaked on opps (because they can act already twice by bidding a major or doubling with nondescript values) while retaining most of the confusion we need to put up with. Awful. Sorry if this sounds blunt but there are awesome, good, okay, bad, and awful ideas, and I reserve my right to use the entire scale, not just the positive side.

[nullve]

Zelandakh, on 2015-July-15, 15:19, said:

Perhaps this would be a good moment to reflect on the differences between an opening bid where no other player has shown strength and a rebid where partner has shown strength and both opponents have passed.

I have reflected on that.

Quote

The multi 2♥ opening you mention is quite popular amongst some of the BBF posters and well known to the majority here.

Sorry. Didn't mean to imply that it's widely unknown among BBF posters, although I'm sure not every BBF poster knows about it. Besides, I was just taking a guess at what you found most "horrible" so I could focus my reply for your benefit.

[nullve]

gwnn, on 2015-July-15, 15:27, said:

2H multi is one of the best conventions in bridge (when NV).

I don't doubt that. Unfortunately it doesn't have the same WBF legal status as a Multi 2C or 2D opening showing either H or S. (Yes, Multi 2D is technically a brown sticker, but WBF makes an exception for it and a similarly defined Multi 2C, as you all know.)

Quote

Here you eliminate almost all the havoc wreaked on opps (because they can act already twice by bidding a major or doubling with nondescript values) while retaining most of the confusion we need to put up with. Awful. Sorry if this sounds blunt but there are awesome, good, okay, bad, and awful ideas, and I reserve my right to use the entire scale, not just the positive side.

It seems to me that you are comparing Multi Squared to Multi 2H, not Multi 2D.

[nullve]

As I've been trying to explain, when you just look at how the 2C opening is defined, Multi Squared is basically a semi-disciplined version of (Garbage) Multi 2D, in the sense that Opener can only have 6 M or 5M4+m if weak, not 5M(332). Some of you have pointed to an obvious theoretical disadvantage, which is that the 2C opening makes it easier for opps to compete than after a similarly defined 2D opening. But that disadvantage should be balanced against the theoretical advantages, some of which I'm going to list below.

(Main) advantages:

1) With inv+ values Responder can relay with 2D instead of 2N as in most versions of Multi 2D. (Obvious advantage.)

2) with < inv values and potentially misfitting hand (i.e. with a singleton or void in a major), Responder will tend to bid 2D first, after which there is a mechanism, or trick (using the "Multi" 2M rebid), for finding out whether Opener has 6 M or 5M4+m, in most cases allowing the partnership to play 2M when Opener has 6 M and to avoid playing 2M when Opener has 5M4+m opposite 1- M. Obviously, Multi 2D lacks an equivalent mechanism, so there is a greater price to paid for lumping 6 M and 5M4+m hands together in the 2D opening.

3) with < inv values and tolerance for both majors, Responder will usually make the same P/C-type of bid that he would playing Multi 2D, but since 2S doesn't promise inv or better values, it's probably easier to bid to the Law level now than after after a similarly defined (Garbage) Multi 2D opening. I don't think Multi Squared has a huge advantage here, but it might still be worth mentioning, particularly since one poster seemed to think that Responder has fewer P/C-type of responses available here than after Multi 2D.)

To give you a better idea of the mechanism in 2), consider a somewhat idealised situation where Responder has 13 hcp and 1M444 shape. Then he will happily play 2M opposite 6 M, but rather play 3m on a 4-4 fit than 2M on a 5-1 fit opposite 5M4+m. So instead of responding, say, 2S (still P/C, but now virtually never done without doubleton spades), he starts by relaying 2D. Then, if Opener rebids 2M, showing 6 M or 5OM4+m, Responder will assume 6 M and pass, but if Opener rebids 2OM, Responder will bid 3C, P/C, allowing Opener to pass with 5M4+C, bid 3D with 5M4+D and to bid 3OM with 6 OM.

To gwnn: Even if we forget about the WBF legal issues with Multi-type 2M openings (relevant where I live, but maybe not so much in, say, Sweden or Australia, where the observation might be of greater interest), the trick just described wouldn't work as smoothly if either

a) all 6M and 5M4+m hands were all lumped together in the 2H opening. (As hard to figure out whether partner has 6 M or 5M4+m as after Multi 2D.)
b) both "Multi" 2M rebids were opening bids instead. (Impossible to play 2H opposite 2+ H when Opener has 5H4+m.)
c) both "Multi" 2M rebids were opening bids instead, but with the meanings of 2H and 2S interchanged. (Impossible to play 2H when Opener has 6 H.)

[Zelandakh]

Are you looking for feedback on your convention or do you just want to convince us that it is as good as you think it is? If the former then accept the feedback and go away and consider if you can improve something; if the latter, good luck to you.

[phoenix214]

It looks like the latter.

[helene_t]

I am not sure if your multi opening is WBF legal given the M+m option.

You say that the 2♦ relay is mostly an invitational+ hand so I think you might want to play the 2M rebid as natural,min and higher rebids as maximum so that you can stop in 2M even with an inviational responder. Alternatively, let the 2M rebid promise 6 so that responder can use the 2♦ relay with shortness in one of the majors and end in 2M opposite a 6-card suit but 3m opposite the M+m hands.

The 2♠ response could be 2-way: spade tolerance but no heart tolerance, OR 2-3S 4+H. With hearts, opener now rebids his minor with the H+m variant and otherwise 2NT, after which responder can still sign off in 3m if he has a long minor suit.

A piece of general advice: it is very difficult to make forum readers take new home-grown conventions seriously, especially if you don't already have a reputation as a good bidding theorist. We have seen so many useless gadgets being proposed here already so the apriori chance is
p(weird gadget, proposed by an unknown poster, is any good) = appr. zero.

So if you want constructive feedback you may try something like this:

- Outline (briefly) a (not too subtle) flaw in estiblished methods. Here it could be some common hand types which responder can't bid effectively when his partner opens a normal multi 2♦.
- Describe (as briefly as possibly but not more briefly!) a simple method which resolves the above.

[straube]

I think nullve has been very polite.

[Zelandakh]

I think these points are blindingly obvious Helene, to the point that I wonder if the OP is an attempt at humour of the Secret Bridge Olympics type. If it is serious then I think it shows a complete lack of understanding of bidding concepts and I would suggest learning these is more important than improving the convention.

[nullve]

Thx for a very thoughtful reply, helene_t

helene_t, on 2015-July-16, 07:23, said:

I am not sure if your multi opening is WBF legal given the M+m option.

It's my impression that it is upoen reading

"EXCEPTION: a two level opening bid in a minor showing a weak two in either major[...]",

but I'm not a bridge lawyer.

Quote

You say that the 2♦ relay is mostly an invitational+

I'm not sure 2D is mostly invitational, but let's assume it is.

Quote

I think you might want to play the 2M rebid as natural,min and higher rebids as maximum so that you can stop in 2M even with an inviational responder.

I've thought about it (likely reason: I've toyed with two-under preempts before), but only superficially, and I must admit it now looks like a reasonable alternative, especially if the 2C opening has a very wide range. I'll defintitely have to think about this possibility again.

Quote

Alternatively, let the 2M rebid promise 6 so that responder can use the 2♦ relay with shortness in one of the majors and end in 2M opposite a 6-card suit but 3m opposite the M+m hands.

I've thought about that, too, but I think it's inferior. Reason: Quite often, Responder will have something like 6 M or 5M1OM(43) and now his best bet (I think) is to play in 2M, hopefully on a 7-card or better fit, instead of 3m on a likely 4-3 fit. In my method he can do that after 2C-2D; 2M-P.

Quote

The 2♠ response could be 2-way: spade tolerance but no heart tolerance, OR 2-3S 4+H. With hearts, opener now rebids his minor with the H+m variant and otherwise 2NT, after which responder can still sign off in 3m if he has a long minor suit.

Ditto, I think. (With something like 1633, Responder would want to play 2H, not 3m, opposite 5S4+m.)

Quote

A piece of general advice: it is very difficult to make forum readers take new home-grown conventions seriously, especially if you don't already have a reputation as a good bidding theorist. We have seen so many useless gadgets being proposed here already so the apriori chance is
p(weird gadget, proposed by an unknown poster, is any good) = appr. zero.

I know.

Quote

So if you want constructive feedback you may try something like this:

- Outline (briefly) a (not too subtle) flaw in estiblished methods. Here it could be some common hand types which responder can't bid effectively when his partner opens a normal multi 2♦.
- Describe (as briefly as possibly but not more briefly!) a simple method which resolves the above.

I was trying to do that in my previous post. That doesn't mean I haven't failed.

[helene_t]

Interesting structure. Thanks for posting. In mushroom maybe 2s could be a sound overcall and bad hands use 2c.

As for the legal issue it may well depend on the mood of your local tc but the concensus seems to be that wilcosz is bsc and this comes very close.

Where is the old Zel who was friendly with everyone? Now you have become an ***** like the rest of us lol

[Zelandakh]

Sorry Helene.

To be fair, I genuinely think this is one of the worst thought out conventions we have seen here. It is certainly possible to make something decent from the basic concept but as a NT defence it is lacking and if we have a system with all calls from 2♣ up available for preempts, we can do better. But more than that, how can anyone take seriously a system stating a pass from dealer showing less than opening strength and a hand unsuitable for preemption is something special?

On the legality I believe you are correct as a Dutch team once tried to get a 2-suited multi past the WBF and it was rejected as BS.