[nofr]

I Would know if You have an expérience to play 2Clubs opening Multi instead of 2Diamonds Multi.

[nofr]

Think for your answer.

[pescetom]

nofr, on 2018-April-26, 08:48, said:

I Would know if You have an expérience to play 2Clubs opening Multi instead of 2Diamonds Multi.

I'm very happy to play neither
But at first thought it looks more problematical than using 2♦, especially if you want to retain 2♥ and 2♠ as artificial openings.
What are the presumed advantages?

[FelicityR]

No experience of playing a Multi 2♣, though I have seen some British experts on BBO use a 2♣ Multi either meaning a traditionally strong 2♣ game force opening, or a weak 2♦ opener as per SAYC or 2/1 system. This then allows them to use the 2♦ opening as a Multi too.

[spotlight7]

FelicityR, on 2018-April-26, 10:38, said:

No experience of playing a Multi 2♣, though I have seen some British experts on BBO use a 2♣ Multi either meaning a traditionally strong 2♣ game force opening, or a weak 2♦ opener as per SAYC or 2/1 system. This then allows them to use the 2♦ opening as a Multi too.

Rubin Two bids:

2C was used as strong natural or weak Ds.

2D was used as strong natural or weak Hs.

2H was used as strong natural or weak Ss.

2S was used as strong natural or a. club preempt

[pescetom]

FelicityR, on 2018-April-26, 10:38, said:

No experience of playing a Multi 2♣, though I have seen some British experts on BBO use a 2♣ Multi either meaning a traditionally strong 2♣ game force opening, or a weak 2♦ opener as per SAYC or 2/1 system. This then allows them to use the 2♦ opening as a Multi too.

So essentially the 2♦ relay response becomes obligatory with almost any hand and the opener with weak diamonds will pass?
I guess why not, the swings and roundabouts are about equal.
I don't think that's what the OP was thinking of, though.

[P_Marlowe]

pescetom, on 2018-April-26, 13:29, said:

So essentially the 2♦ relay response becomes obligatory with almost any hand and the opener with weak diamonds will pass?
I guess why not, the swings and roundabouts are about equal.
I don't think that's what the OP was thinking of, though.

It also prevents some interventions, given that 2C can be weak, weak preemptive
overcalls of the 2C opening loose their appeal.
Partner can also make a preemptive raise to 3D, with diamond support.

With kind regards
Marlowe

[pescetom]

P_Marlowe, on 2018-April-26, 14:08, said:

It also prevents some interventions, given that 2C can be weak, weak preemptive
overcalls of the 2C opening loose their appeal.

Certainly so.

P_Marlowe, on 2018-April-26, 14:08, said:

Partner can also make a preemptive raise to 3D, with diamond support.

I'm more dubious about this - I wouldn't be happy giving up an entire level of bidding (and the possibility to impose trumps) if I was opener with a very strong hand in a major and my partner decided to preempt me with diamonds.

[nullve]

nofr, on 2018-April-26, 08:48, said:

I Would know if You have an expérience to play 2Clubs opening Multi instead of 2Diamonds Multi.

I play

2♣ = a) weak w/ either 6M3-OM ("Weak Two") or 5M3-OM4+m ("Muiderberg") b) various strong hands,

and the main reason I use 2♣ instead of 2♦ for this is that it allows

2♣-?:

2♦ = a) < INV, either 1- M ("potential misfit"), 6+M2-OM or 3S(3)4+H b) various INV+ hands
...2♥ = weak, either 3-S6H or (NB!) 5S3-H4+m
......P = < INV, either 1- H (reason to think Opener has 6 H), 2-S6+H (reason to think Opener has 5 S) or (best bet w/) 15(43)
......2♠ = P/C w/ 3S(3)4+H
......2N = INV+ relay
......3♣ = P/C, usually w/ 1- S
......(...)
...2♠ = weak, either 6S3-H or (NB!) 3-S5H4+m
......P = < INV, either 1- S (reason to think Opener has 6 S), 6+S2-H (reason to think Opener has 5 H) or (best bet w/) 51(43)
......2N = INV+ relay
......3♣ = P/C, usually w/ 1- H
......(...)
......3♥ = P/C w/ 3S(3)4H
......3♠ = P/C w/ 3S5+H
......(...)
...2N+ = strong hands
2♥ = P/C, usually w/ either 2+S2H or (3)4+S3H
2♠ = P/C, usually w/ 2S3+H
(...),

which makes partscore bidding much easier than after an identically defined 2♦ opening.

The trick involving the "multi" 2M rebid over 2♣-2♦ doesn't always work, but here are the only two boards from online play where Responder was unable to "guess" which major Opener had (by following the system and not actually guessing):

From 2012:

Spoiler

---

From 2018:

Spoiler

---

[nullve]

pescetom, on 2018-April-26, 09:51, said:

But at first thought it looks more problematical than using 2♦, especially if you want to retain 2♥ and 2♠ as artificial openings.

Why?

[pescetom]

pescetom, on 2018-April-26, 09:51, said:

But at first thought it looks more problematical than using 2♦, especially if you want to retain 2♥ and 2♠ as artificial openings.

nullve, on 2018-April-28, 06:15, said:

Why?

Because if most or all strong hands are still going to transit through 2♣ then it would be logical for responder to bid a 2♦ waiting relay or indicate a suit of his own, but this seems hard to reconcile with the desire to show a pass/correct preference for opener's possible weak 6-card ♥ / ♠.

[nullve]

pescetom, on 2018-April-28, 07:39, said:

Because if most or all strong hands are still going to transit through 2♣ then it would be logical for responder to bid a 2♦ waiting relay or indicate a suit of his own, but this seems hard to reconcile with the desire to show a pass/correct preference for opener's possible weak 6-card ♥ / ♠.

There's no inherent reason why most strong hands still have to go through 2♣ instead of, say, 2♦, but here's one possibility:

nullve, on 2018-March-03, 09:08, said:

2♣ = bad Weak Two in a major OR strong (GF if unBAL) without 5+M4+OM
2♦ = Ekren, either weak or GF
2M = constructive Weak Two

2♣-?:

2♦ = relay, can stand the 3-level opposite a bad Weak Two*
...2♥ = Kokish OR bad Weak 2♠ (NB!)
......2♠ = relay, not exactly INV opposite bad Weak 2♠
.........2N = BAL
.........3♣ = strong, 5+H4+C
.........3♦ = strong, 5+H4+D
.........3♥ = strong, 6+ H
.........3♠ = bad Weak 2♠ (NB!)
.........(...)
......2N = INV+ opposite bad Weak 2♠, relay
......(...)
...2♠ = strong, 5+ S, unBAL OR bad Weak 2♥
......2N = relay, not exactly INV opposite bad Weak 2♥
.........3♣ = strong, 5+S4+C
.........3♦ = bad Weak 2♥ (NB!)
.........3♥ = strong, 5+S4+D (NB!)
.........3♠ = strong, 6+ S
.........(...)
......3♣ = INV+ opposite bad Weak 2♥
......(...)
...2N+: same as 2N over 2♣-2♦ in standard
2♥ = P/C
...P = bad Weak 2♥
...2♠ = bad Weak 2♠
...2N+: not sure*, but maybe
...2N = strong, 5+ H, unBAL OR BAL
......3♣ = Puppet Stayman-like
.........3♦ = BAL, not 5 S
.........3♥ = 6+ H (unBAL)
.........3♠ = BAL, 5 S
.........3N+ = 5 H, unBAL
......3♦ = 5+ S
.....(...)
...3♣ = strong, 5+ C, unBAL
...3♦ = strong, 5+ S, unBAL
...3♥+ = strong, 5+ D, unBAL
...?
2♠ = P/C
...P = bad Weak 2♠
...2N+: not sure*, but maybe
...2N = strong, 5+ S, unBAL OR BAL
......3♣ = Puppet Stayman-like
.........3♦ = BAL, not 5 H
.........3♥ = BAL, 5 H
.........3♠ = 6+ S (unBAL)
.........3N+ = 5 S, unBAL
......3♦ = 5+ H
.....(...)
...3♣ = strong, 5+ C, unBAL
...3♦ = strong, 5+ H, unBAL OR bad Weak 2♥
...3♥+ = strong, 5+ D, unBAL
...?
(...)

* It helps a lot if 2N over 2♣-2M is GF, but then the 2M response has to promise some values. So maybe the 2♦ response should also include very weak hands regardless of 3-level safety?

Yes, if Responder has 3+S3+H, then he's not immediately able to preempt to the limit opposite a bad Weak Two, but must respond 2♦.

[helene_t]

Probably 2♦ should be the strong relay, allowing us to stop in 2M when opener has minimum. This also frees 2NT for other purposes.

Some people here in NZ play 2♣ multi but they seem to play 2♦ as a generic relay which is obviously not good. But I must admit I haven't asked them what 2♥ and 2♠ would mean. If they are both semipositive then it is ok.