[Kungsgeten]

I got inspired by Cthulluh D's thread about a weak/strong 1NT opening. Here's my take on it (not tested and not proof read): The Multi 1NT.

1NT shows a strong no trump (like 15--17) or a weak two in one of the majors. The document don't contain information about when the opponents interfere. I guess such an opening bid would be best to use only when not vulnerable.

[whereagles]

A quick back-of-the-envelope simulation yields


Weak var = 35.79% (5-11 HCP, 6 cards, at least 4 HCP in main suit)
Strong var = 64.21% (15-17 HCP, ok to open with 5CM)

So it's mostly strong... I'm surprised with this. I thought the weak variant would be more frequent.

Note: pulling 5CM out of the strong variant gives weak/strong = 38.79% / 61.21%.

[Cthulhu D]

One minor omission, I'm guessing 1NT-2S-3S should be explicitly a weak hand with spades?

[Kungsgeten]

Yeah, 1NT-2S; 3S should be weak with spades. Perhaps weak with spades should be allowed to splinter to the 4-level too.

[hrothgar]

I'd argue that this is better as a strong NT or a weak three in either minor
(You get to keep Stayman)

[rbforster]

 hrothgar, on 2014-October-23, 16:39, said:

I'd argue that this is better as a strong NT or a weak three in either minor
(You get to keep Stayman)

This looks pretty simple:

1NT: weak two in a minor, or 15-17 balanced

2♣ invitational+ stayman (8-13 or so), not invitational opposite the weak options
....P weak clubs
....2♦ weak diamonds
....2M natural, strong NT
....2N no 4M, strong NT

Less clear how much of the strong NT you can keep here, since it will be hard to end below 3m otherwise opposite the weak hand.

[Cthulhu D]

I think he is suggesting having a 3 clubs or 3 diamonds call in the strong NT - so responses are easy, regardless of what partner does, bid 3m

This lets you play 3C as 5/5 minors, and 3D as something like 6 diamonds + 4M but I'm not hugely sure I am a fan of that diamond bid, despite currently playing it.

[Kungsgeten]

 rbforster, on 2014-October-24, 17:52, said:

This looks pretty simple:

1NT: weak two in a minor, or 15-17 balanced

2♣ invitational+ stayman (8-13 or so), not invitational opposite the weak options
....P weak clubs
....2♦ weak diamonds
....2M natural, strong NT
....2N no 4M, strong NT

Less clear how much of the strong NT you can keep here, since it will be hard to end below 3m otherwise opposite the weak hand.

You could use this if 1NT shows one of the majors too:

1NT--2C;
2D = Weak (regular multi continuations)
2M = Strong, natural
2NT ='Strong, no major, min
3C = Strong, no major, max

[Free]

Why would want to ruin your strong NT ànd you weak two's? What's the upside?

[Cthulhu D]

 Free, on 2014-October-28, 00:48, said:

Why would want to ruin your strong NT ànd you weak two's? What's the upside?

I suspect being able to bid a weak 2 in clubs will be a big winner, and with my original line of thinking it was that, I cannot bid a weak 2 in hearts naturally so it would be nice to be able to do so. Testing reveals it is not hugely workable because I think the costs on the predominant strong NT hands (50% more frequent than the weak options) outweighs the negatives, but you need to try these things to find out!

I suspect at the table it will result in strange responses to your 1NT openings as well because most people are exceptionally bad against defending against Strong or Weak type hands where the frequency of the weak options is close to the frequency of the strong options for no reason I can deduce.

[Kungsgeten]

 Free, on 2014-October-28, 00:48, said:

Why would want to ruin your strong NT ànd you weak two's? What's the upside?

The main upside would probably be the same as playing Multi 2♦: You get to play weak twos in the majors, but can still use the 2M bids for something else. Multi 1NT also frees up 2M, but also leave 2♦ untouched.

Another aspect is that the Multi 1NT probably is pretty hard to defend, especially after 1NT-pass-pass. If opener has the weak variant now, it is the opponents' board, but do fourth hand dare to act when opener can be strong?

I think the main downside is when the opponents interfere, and also that it is hard to preempt further.

If playing Multi 1NT, you could have a lot of wild preempts (if into that):

1NT = 15--17 bal or weak in one of the majors
2♣ = Strong or weak with diamonds
2♦ = 5-5 in two suits, but not the minors
2♥ = A 4 card major and 5+ diamonds
2♠ = At least 5-4 minors

Or perhaps something more constructive (but then the Multi 1NT probably do not have as much appeal):

1NT = Multi
2♣ = 18--20 bal
2♦ = Any GF
2M = 6+ suit, 10--13

[rbforster]

One benefit would be that most people's default NT defenses (Cap, Woolsey, etc) are not going to be as good against this Multi NT. Most standard strong NT defenses are major-oriented to compete at the 2 level, and you're a lot less likely to want to show both majors if someone has a 6+ major on the other side.

[Free]

 rbforster, on 2014-November-02, 06:05, said:

One benefit would be that most people's default NT defenses (Cap, Woolsey, etc) are not going to be as good against this Multi NT. Most standard strong NT defenses are major-oriented to compete at the 2 level, and you're a lot less likely to want to show both majors if someone has a 6+ major on the other side.

If you use your weak NT defense, you're pretty much covered imo. Only the Dbl is a bit risky...