[ttti]

I have read an article (from Sweden I suppose), which mentioned a system, where the "normal" 1 ♠ and 1 NT responses to (at least) 1 ♣ are inverted. 1 ♠ denies 4 card ♠ and ♥. 1 NT is 4+ ♠.

I don't find this article any more. Have You heard or played this kind of system? What are the point ranges for 1♠ and 1 NT?

[fromageGB]

I haven't heard of it been used over a minor open, but I do play something similar - Kaplan inversion - over a 1♥ open. My 1NT is 5+ spades, but I have heard of 4. The point ranges are related to those you would use for the bids as you would play uninverted, so 1NT is expected to be 6+ hcp unlimited, while 1♠ can now be also unlimited, as it is forcing. So a basic flat 6-10 can bid 1♠ and pass 1NT, while a stronger responder would bid on.

[ttti]

 fromageGB, on 2018-February-09, 04:22, said:

I haven't heard of it been used over a minor open, but I do play something similar - Kaplan inversion - over a 1♥ open. My 1NT is 5+ spades, but I have heard of 4. The point ranges are related to those you would use for the bids as you would play uninverted, so 1NT is expected to be 6+ hcp unlimited, while 1♠ can now be also unlimited, as it is forcing. So a basic flat 6-10 can bid 1♠ and pass 1NT, while a stronger responder would bid on.

Thank You. Now I see the light. I misread (and more probably misunderstood) the article, I thought it is applied after (2+) 1 ♣.

So 1 NT is forcing as 1 ♠. What about the same approach after (4+) 1 ♦?

[steve2005]

 ttti, on 2018-February-09, 05:31, said:

So 1 NT is forcing as 1 ♠. What about the same approach after (4+) 1 ♦?

There are methods that play 1N as forcing after 1♦ but they are not common. A method using Gazilli or something similar over 1♦ is one.
But Kaplan Inversion is over 1♥ openings.

[Kungsgeten]

 ttti, on 2018-February-09, 05:31, said:

Thank You. Now I see the light. I misread (and more probably misunderstood) the article, I thought it is applied after (2+) 1 ♣.

So 1 NT is forcing as 1 ♠. What about the same approach after (4+) 1 ♦?

After 1♥-1NT (showing 5+ spades) you sometimes have to rebid a 3-card club suit, if you have 2-5-3-3 distribution. It is more problematic after 1♦-1NT, if 1NT shows 5+ spades:

- 1-4-5-3 would probably need to rebid 2♣, if too weak to reverse. Or maybe 2♦?
- 2-4-4-3 would also rebid 2♣. Not a problem if 1♦ promises an unbalanced hand.
- 2-3-5-3?

Also I'm not really sure what the benefits of this treatment would be, but a low-level forcing bid can probably be useful. Over a 1♦ opening:

1♥ = Artificial and forcing. Usually 0-4 spades and 0-3 hearts, but could have longer majors if game forcing.
1♠ = 4+♥.
1NT = 5+♠, forcing.