[helene_t]

I just got a crazy idea. I was thinking that maybe raises such as
1♦-(2♣)-3♦
1♦-(2♣)-3♣

should promise (or ostensibly show, in the second case) for example both red suits rather than just diamonds.

It started with an attempt to work out a fairly vanilla freebid structure for a weak-NT system (I don't think it matters so much whether it is 4cM or 5cM):

1♦-(2♣)-?

dbl: 7+ points most hands
2♦: 6-8 points (can be three diamonds if 1♦ shows 4+)
2M: 7-11, 6+ cards
2NT: 7+ points, 5-5 majors
3♣: 11+, diamond support
3♦: 9-10, diamond support

With that structure, you would double with a diamond raise and a major (unless distributional enough for a 3M fitbid), but maybe that is backwards: if you have a diamonds only you are less likely to have club shortage and therefore more likely to tolerate opener converting the double.

So maybe it is more attractive to double with diamonds only, and then let the direct raises show a specific side suit (probably hearts) to reduce the strain on the double a bit?

Any thoughts?

[DavidKok]

This puts a lot of strain on the double, especially since your 2M promises 6. In fact, with negative free bids it now shows either "a hand, possibly weak, with one or both majors (can be a 5-card suit)" or "any hand too strong for a negative free bid". I would place much more emphasis on clarifying major suit length, since you may be in no-mans land if lefty raises the clubs.
Normally showing majors takes priority over minors, so 3♣ here would usually show some club length as well (sure, one day you'll pick up 3=3=5=2 on this auction. But most of the time you won't have a 4cM and your support won't be a 5(+)-card suit). Also important is that at IMP scoring the most likely game on this start, especially if responder doesn't show a major suit, is 3NT. I think there is merit in restructuring your diamond raises so that opener has a better time placing the contract.

I'm happy to share what I play, but I'm not sure how relevant it is. I play unbalanced diamond, strong NT and no negative free bids.

[mikeh]

In one partnership, we play transfer fit bids starting with the 3 level cue and ending below 3 of our suit. It doesn’t apply when, as in your example, they opened the suit just below our suit.

Say (1C) 1S (2C) ?

3C shows diamonds and spades, invitational or better
3D shows hearts and spades
3H shows an invitational raise with no side suit
3S shows a mixed raise

Has never come up yet, but we’ve only played this for perhaps 500 hands.

Over say 1D, we have fewer options since (1D) 1S (2D) 3C is needed as natural, so the only fit bid is 3D, showing hearts and spades

[helene_t]

DavidKok, on 2022-April-13, 05:21, said:

I would place much more emphasis on clarifying major suit length, since you may be in no-mans land if lefty raises the clubs.

Yes good point.

If you have to double with xx-Kxx-AJxxx-xxx you are not so happy if it starts
1♦-(2♣)-x-(3♣)
3♠

But then again, a minimum double with a doubleton spades is even more likely if we don't raise diamonds with both red suits.

So something like Han's structure where an immediate 2♦ shows 4-5 hearts and 3+ diamonds (I think that was how it was defined; anyway, something like that) but deny spades would allow the double to be more well-defined.

In a strong-notrump system you may prefer just to pass with many awkward 7-9 counts and/or allow a negative freebid on a 5-card suit but in a weak NT system those options are less attractive, so a lot of hands that can't raise will have to double.