[pescetom]

There is some symmetry here
with my previous post, in that I am unfamiliar with inverted minors and guessing a bit. But my 3♣ and GiB's 3♥ both seemed reasonable and coherent with the explanations. Now 3♠ was explained as some preposterous number of spades rather than an ask, so I punted 3NT which did not look unlikely anyway.
WTF (as might say an eminent contributor, now for hire) is 4♥ about?

[a_user]

Your 3NT bid was a little exuberant and now your partner is cueing its way to slam.
After all, if its got 15+ HCP and you've got 15+ HCP, it must be time to break out the Prosecco and invert the bottle over your minors.

[steve2005]

Well the mistake is the explanation of 3♣ is wrong.
Surely 3♣ is passable so it should be 11-13 hcp not 11-21
and 3♥ is essentially game forcing, unless you think you can somehow stop in 4♣
So 3♥ should be showing 14 or 15+ hcp not 10+

3NT should not be showing 15+ hcp it merely shows the 11 you have promised plus stopper in the black suits

[Huibertus]

steve2005, on 2025-December-01, 20:13, said:

Well the mistake is the explanation of 3♣ is wrong.
Surely 3♣ is passable so it should be 11-13 hcp not 11-21
and 3♥ is essentially game forcing, unless you think you can somehow stop in 4♣
So 3♥ should be showing 14 or 15+ hcp not 10+

3NT should not be showing 15+ hcp it merely shows the 11 you have promised plus stopper in the black suits

The actual bidding shows the problem is NOT the explanation of 3NT. If the explanation was wrong and the agreement was right, there would be a pass on 3NT. The actual explanation and sub sequent auction also shows the actuall agreement on 3 ♣ is it can contain more than a minimum, which, yes, is stupid.

The agreements cause North to investigate slam, expecting more from south.

As stupid as these agreements are, it's not unreasonable of North to act upon it, trusting partner.

[pescetom]

 Huibertus, on 2025-December-02, 04:58, said:

The actual bidding shows the problem is NOT the explanation of 3NT. If the explanation was wrong and the agreement was right, there would be a pass on 3NT. The actual explanation and sub sequent auction also shows the actuall agreement on 3 ♣ is it can contain more than a minimum, which, yes, is stupid.

The agreements cause North to investigate slam, expecting more from south.

As stupid as these agreements are, it's not unreasonable of North to act upon it, trusting partner.

Even if the agreement is that 3♣ can contain much more than a minimum (which is illogical, given that it has to be non-forcing and compatible with a minimum), North has no apparent reason to assume it is not a minimum, nor a hand that could be interested in slam opposite a minimum.
After the 3♥ game force showing a stopper (which is quite logical, agreed), at least one of 3♠ and 3NT has to promise no more than a minimum and willingness to stop in 3NT. If it was 3♠ then it was grossly misexplained.

[smerriman]

GIB's treatment of inverted minors is totally messed up.

In Matt's pre-BBO version, it was super basic - after 1m - 2m:

- 2NT showed a minimum balanced hand (no stoppers required)
- 3m showed a minimum with extra length in the minor
- 2 of a new suit showed some extras and a stopper, over which partner can choose whether to play in NT or not.

Probably not brilliant, but at least coherent.

Whether that changed or not up to BBO v18 I don't know.

In v19, BBO "Improved Inverted Minor sequences" (no details provided).

In v21, BBO then "Tweaked the inverted minor sequence. GIB will now provide more accurate information and point limits as both opener and responder."

This is the Windows version where I can see the database. The above bids were generally unchanged, but a lot more general rules were added about continuations when in a low level forcing auction.

Except it also had what appears to be a major bug that treated every 2♣ response to an opening bid as matching the 2 over 1 ruleset. This resulted in conflicts with 1♣ - 2♣ - e.g. 1♦ - 2♦ - 2♥ showed 15+ while 1♣ - 2♣ - 2♥ showed 16+, and 1♣ - 2♣ - 3♣ was suddenly 12-22 points while 1♦ - 2♦ - 3♦ was 12-14.

In v22, the logic was overhauled: "You can expect GIB to be more consistent as both opener and responder in inverted minor sequences. With stoppers in all unbid suits, GIB will bid NT. With an unbalanced hand, GIB will now bid the closest new unbid suit to indicate a stopper there.".

So now opener was required to bid its cheapest stopper, or NT with all stoppers. Yet this only applied to opener; responder couldn't bid a stopper or 2NT without extra values, leading to confusion over whether stoppers were held or not. Even barmar noticed this was odd and not "standard", asking the main developer at the time what the reasoning was (without a public response).

It wasn't until several years later when v33 was released with: "After an inverted minor suit raise, if responder rebids a suit on the 2 level or 2NT it will no longer be forcing to game, allowing for investigation of stoppers while still stopping in a partscore.".

So now after 1m - 2m, unless looking for slam, both players are meant to bid their cheapest stoppers (i.e., you bid 2♥) until you have enough information on whether to play 3NT or not.

One of the problems is, virtually all of the bids now don't limit your hand in any way. But the general rules for 3NT requiring 25 points apply, which is why it's defined as 15+ even if you had no alternative to show a minimum (well, you did with 4♣, but..)

Though GIB would bid 2♥, denying a diamond stopper, then have its partner jump to 3NT anyway. Which isn't an unreasonable auction, though not really intentional.

And I suspect the original bug with 2♣ responses is still there, since even though you're not meant to bid 3♣ here, 1♦ - 2♦ - 3♦ is limited to a max of 16, while the same isn't true of clubs..

tl;dr nobody has a clue what is going on. But then again, nobody really cares either.