[nullve]

Although Responder cannot preempt as aggressively opposite a Multi 2♦ if it contains a strong balanced option, I doubt a response structure has to be as ineffective as several posters have claimed recently.

For example, over a 6c Multi with a (not too weak) strong BAL option, once could (in theory) play something like

P: allowed (e.g. with xxx x Jxxxx Txxx or maybe AKx --- AJxxxx Qxxx)
2♥ = P/C w/ either 1- H or 2H3+S OR (optionally) INV w/ 5+H(2?)1-S
2♠ = P/C w/ 2-S2+H OR (optionally) INV(+?) w/ 5+S(2?)1-H
2N = relay, either 5+S4+H or INV+ (wrong-sides NT with 5S4H opposite 2S2-3H, unfortunately)
...3♣ = MAX Weak 2M OR BAL, unwilling to agree H opposite 5+S4H
......3♦ = GF relay
.........3OM = MAX 2M
............3N/4M = to play
.........3N(+) = BAL
......3♥ = was < INV, 5+S4H (no danger of wrong-siding H)
.........3♠ = BAL, 3-5 S (agrees S)
.........3N = BAL, 2S2-3H
.........4M = Weak 2M
......3♠ = ?
......3N = was < INV, 5+S5+H
.........4M-2 = BAL, agrees M
............4M-1 = right-siding puppet to 4M
............(...)
.........4M = Weak 2M
...3M-1 = MIN Weak 2M
......3M/3N/4M = to play
...3♠+ = BAL, 4-5 H (agrees H)
......(...)
......4♦ = right-siding puppet to 4♥
......(...)
3♣ = < INV, either 3-4S3H or 4S4H
...3♦ = BAL, 4 M
......3♥ = 4S3H
.........3♠ = 4 S (agrees S)
.........3N = 4H3-S
......3♠ = 3S3H (right-siding puppet to 3N)
......3N = 4S4H, NF
.........4M-2 = 4 M
............4M-1 = right-siding puppet to 4M
............(...)
...3M = Weak 2M
...3N = BAL, no major
...4M-2 = BAL, 5 M
......4M-1 = right-siding puppet to 4M
......(...)
3♦ = < INV, 5+H3-4S
...3♥ = BAL, either 3-5 H or 4 S
......3♠ = 5+H3S
.........3N = 4S2H
.........4♣+ = 3-5 H (agrees H)
......3N = 5+H4S (F)
...3♠ = Weak 2♠
...3N = BAL, 2(3)H2-3S
...4♣ = BAL, 5S2H (agrees S)
......(...)
......4♥ = right-siding puppet to 4♠
......(...)
3♥ = < INV, 5+S3H
...P = Weak 2♥
...3♠ = BAL, 3-5 S
...3N = BAL, 2(3)S2-4H
...4♣ = BAL, 5H2S (agrees H)
3♠ = < INV, 4H3S
...3N = BAL, 2-4S2-3H
...4♣ = BAL, 4-5 H (agrees H)
......4♦ = right-siding puppet to 4♥
...4♦ = BAL, 5 S (agrees S)
...4♥ = Weak 2♥
3N+: as in more standard Multi 2♦ structures, perhaps gambling that Opener doesn't have the strong BAL option

(I will correct errors when I find them. Note that the 3♣ and 3R responses bear some resemblance to Puppet Stayman and Jacoby transfers, respectively.)

I'm sure structures that are both simpler and more effective are possible.

Thoughts?

This post has been edited by nullve: 2023-March-31, 03:54

[DavidKok]

I think you're being too generous, and didn't address the main issue.

Conditional on responder being 'weak' (less than invitational opposite the weak two in a major suit) with length in both majors (at least 3-3(+)) responder is actually quite likely to have a strong hand. Whenever this happens responder, or in this case the system design, is faced with the annoying risk of preempting our own constructive auction or not raising to the limit facing the weak option. As an extreme example give responder ♠Kxxx, ♥Axxxx, ♦xxx, ♣x and you will be well placed over either a 20-21 or 20-22 2NT opening or over a weak 2M opening, but not over a 2♦ multi containing both. You'll also have to bid regularly with, say, flattish 8-14 counts for fear that you're missing a good contract (or 8-14 non-flattish hands, but you won't get to bid your suits). This gives the opponents multiple rounds to enter the auction.

I think this shows in almost every bid that you're suggesting. In order:

• Pass: facing weak-only we can pass far more often, including on a number of hands without great diamond length. It is very difficult for the opponents to punish us, or even decide how far to compete, if pass is not descriptive. An example hand of a weak multi pass is ♠Kxx, ♥x, ♦Qxxx, ♣xxxx, gambling that opener has hearts. I think it is anti-percentage to pass a can-be-strong multi with this hand type (and again: notice that you are well placed facing a 20-22 balanced opening, but not facing a multi).
  
• 2♥: weak-only bidders can include hands that have heart support but prefer 3m to 2♠, and even hands that prefer 3♥ to 2♠ facing spades.
  
• 2♠: this need not promise hearts in the weak-only version.
  
• 2NT: the weak hands with both majors could have stolen far more bidding space facing a weak version.
  
• 3♣: also far under the LAW (weak-only bidders would choose between 3♠, 4♣, 4♦ and 4♥ with this hand type). You also seem to have sacrificed the ability to explore game in the other major, and possibly minor suit contracts.
  
• 3♦: ditto.
  
• 3♥: facing weak-only this is probably a 3♥ bid as well, although it only requires 4 spades in that case.
  
• 3♠: these bids are identical (I think).

Mikeh also made the good point that 4♣ through 4♥ should not contain weak hands with both majors facing an ambiguous strength multi, while they should facing weak-only. So you're losing on pressure bids in that regard.

I'm sure your structure is playable, but you're regularly giving the opponents a level or two of bidding space they don't deserve. There's also multiple hand types missing from the structure (for now, I presume). E.g. partner opens 2♦ and you have ♠x, ♥AQJxxx, ♦AKx, ♣QTx - how do you investigate 3NT vs 4♥ (versus partscore)?

[nullve]

 DavidKok, on 2023-March-30, 09:27, said:

There's also multiple hand types missing from the structure (for now, I presume). E.g. partner opens 2♦ and you have ♠x, ♥AQJxxx, ♦AKx, ♣QTx - how do you investigate 3NT vs 4♥ (versus partscore)?

Responder could start with 2♥, now either P/C OR INV w/ 6+H1-S. (See edit.) I do something similar in my own (5-6c) Multi.

[DavidKok]

Sure, add an ace and try again. Or remove a heart and risk getting passed.

[nullve]

 DavidKok, on 2023-March-30, 09:27, said:

[*]3♣: also far under the LAW (weak-only bidders would choose between 3♠, 4♣, 4♦ and 4♥ with this hand type). You also seem to have sacrificed the ability to explore game in the other major, and possibly minor suit contracts.

Yes, the Law level would be reached opposite the weak hand only after 2♦-3♣; 3M or 2♦-3♣; 3M-4M.

Maybe it would better to do as Cyberyeti and respond 3N with the < SI 4S4H hands. That would be Law-ful but also wrong-side NT opposite 2-3S2-3H.

 DavidKok, on 2023-March-30, 09:27, said:

[*]3♣: also far under the LAW (weak-only bidders would choose between 3♠, 4♣, 4♦ and 4♥ with this hand type). You also seem to have sacrificed the ability to explore game in the other major, and possibly minor suit contracts.

I don't think so. Note that with < INV and 4H3S the response to 2♦ is 3♠, which explains why this hand type is not shown after 2♦-3♣; 3♦.

[nullve]

 DavidKok, on 2023-March-30, 10:18, said:

Sure, add an ace and try again. Or remove a heart and risk getting passed.

Bidding INV+ hands with the opposite major is tricky, to say the least, in simple versions of Multi, such as the one just given by

2♦-?:

2M = P/C
2N = INV+ relay
...3♣ = MAX Weak Two
......3♦ = GF relay
.........3OM = MAX Weak 2M
...3M-1 = MIN Weak 2M

that I based the OP structure on.

I'm not sure which sequence(s) "risk getting passed" refer to, but it seems that you'd like to know how Responder is supposed to bid hands like

a) x AQJxxx AKx AQT (GF hand, 6-2 or 6-3 H fit possible)
b) x AQJxx AKxx QTxx (INV hand, 5-3 H fit possible)

as well.

Although I didn't focus on this type of problem at all when starting the thread, my solution in the context of a 5-6c Multi, and one that should work at least as well here, is actually to respond 2♥ with b) and maybe a) as well, depending on which tools are available with GF hands. So

2♦-2♥ = P/C (as in the OP) OR INV(+), 5+H(2)1-S

(and, more generally,

2♦-2M = P/C (as in the OP) OR INV(+), 5+M(2)1-OM)

and then over 2♦-2♥; 2♠ Responder is theoretically in a better position than over a Weak 2♠ opening.

I will update the OP structure.

[DavidKok]

I'd bid 3♣, inv(+) with 5(+) hearts and asking for opener's heart holding. If partner shows heart shortness I'll bid 3NT with the first and choose between 3♥ and 3♠ with the second. I've already missed my first 6-6 major suit fit in only two weeks, I think adding weak hands with hearts to 2♥ is fine but inv(+) is gambling.

[pescetom]

 nullve, on 2023-March-31, 03:47, said:

Bidding INV+ hands with the opposite major is tricky, to say the least, in simple versions of Multi, such as the one just given by

2♦-?:

2M = P/C
2N = INV+ relay
...3♣ = MAX Weak Two
......3♦ = GF relay
.........3OM = MAX Weak 2M
...3M-1 = MIN Weak 2M

that I based the OP structure on.

I'm not sure which sequence(s) "risk getting passed" refer to, but it seems that you'd like to know how Responder is supposed to bid hands like

a) x AQJxxx AKx AQT (GF hand, 6-2 or 6-3 H fit possible)
b) x AQJxx AKxx QTxx (INV hand, 5-3 H fit possible)

as well.

Although I didn't focus on this type of problem at all when starting the thread, my solution in the context of a 5-6c Multi, and one that should work at least as well here, is actually to respond 2♥ with b) and maybe a) as well, depending on which tools are available with GF hands. So

2♦-2♥ = P/C (as in the OP) OR INV(+), 5+H(2)1-S

(and, more generally,

2♦-2M = P/C (as in the OP) OR INV(+), 5+M(2)1-OM)

and then over 2♦-2♥; 2♠ Responder is theoretically in a better position than over a Weak 2♠ opening.

I will update the OP structure.

Bye one of those odd coincidences that occur, I caught my opponents playing something very similar yesterday. They had explained 2H as P/C, and reluctantly too. I wasn't damaged but it reinforced my conviction that many gains from this convention derive from inadequate disclosure.

[nullve]

 DavidKok, on 2023-March-31, 03:51, said:

I'd bid 3♣, inv(+) with 5(+) hearts and asking for opener's heart holding. If partner shows heart shortness I'll bid 3NT with the first and choose between 3♥ and 3♠ with the second. I've already missed my first 6-6 major suit fit in only two weeks, I think adding weak hands with hearts to 2♥ is fine but inv(+) is gambling.

You seem to borrow from Woolsey and play

2♦-[3M-2]*; ?:

* INV+, 5+ M

3M-1 = 0-1 M
3M = 2 M
3M+1 = 3 M
other = long M,

but then you're gambling that knowing whether Opener is MIN or MAX is unimportant, aren't you?

I mean, if the bidding goes

2♦-3♣*
3♥**,

* INV+, 5+ H
** 2 H

doesn't Responder sometimes want to be in game opposite only opposite a MAX opener?

[DavidKok]

Yes, if you want to be in game opposite a doubleton and MAX but not opposite a doubleton and MIN this treatment won't help you yeah. I am not sure how to solve that.