[Knurdler]

In another post I asked what to do when they interfere with our 1NT and was recommended Rubensohl.
I have now worked my way through a not too complicated version from www.acblunit390.org/Simon/rubensohl.htm

As usual, I have questions to which I cannot find answers on the net.

After 1NT (2D) … apparently 3 spades by responder is a transfer to 3NT without a diamond stop (and denies 4 hearts).
What does opener do if they also lack a diamond stop?

After 1NT (2H) … apparently 3 diamonds by responder is a special purpose transfer to the overcaller’s suit.
I understand this bid is a game force and asks opener if they have 4 spades and does not promise a heart stop.
With 4 spades, opener can bid 3 spades.
Without 4 spades but with a heart stop, opener can bid 3NT.
Apparently, without 4 spades and without a heart stop, opener completes the transfer and bids 3 hearts.
Now what does the responder do?
If they have a heart stop, they can bid 3NT.
But where can they go without a heart stop?

After 1NT (2H) 2NT (P) 3C … I understand that responder can pass if weak.
Responder can bid 3 spades to show 6 clubs and 4 spades – is this invitational or forcing?
Without 4 spades, what does responder need to bid 3NT?
My guess is 10 points and a half heart stop?

After 1NT (2H) 3H (P) 3S … Apparently responder with only 5 spades can bid 3NT.
Does this suggest responder has 10+ points?
How can responder bid 3NT without a heart stop?
Another site suggests that responder can pass 3 spades. Does that suggest the 3 heart transfer bid only needed 8-9 points?

Thank you

[mycroft]

If neither have a stop in the opponents' suit, you can't play 3NT.

You usually have a fit in some suit (in most of your cases, a minor, but the 4-3 other-major fit should never be discounted); it's the one who knows 3NT is not an option's job to start looking for it.

If that's opener, you have the advantage that it "can't be" a self-supporting long suit (although some will open on 6m322), so with no fit, responder is free to continue the scramble.

If it's responder, there's a chance that "stopper for 3NT" overrode any thought of stating their suit (less so in Rubensohl, of course, which will always get another call) so opener has to be more wary of pulling. But opener "should have" at least xx in the suit, so responder is more likely to be able to place the contract.

Like anything, "preempts work™" sometimes, even at the 2 level. It's possible that the last making contract is only available in the rear-view; it's possible that a poor suit will be trump with a much better one available that you would have found if it weren't for the pesky opponents telling each other what to lead. It's also possible that the interference is the only way to avoid the doomed 3NT and any plus score is a win!

I am not a Rubensohl specialist (so if those that are disagree with me, listen to them!), but traditionally in these auctions, you "concede" the invitational call opposite the tightly limited hand to the interference; therefore second bids are "looking for the best game". I would expect that any invitational call will be *clearly marked* in the notes, in fact.

[mycroft]

If neither have a stop in the opponents' suit, you can't play 3NT.

You usually have a fit in some suit (in most of your cases, a minor, but the 4-3 other-major fit should never be discounted); it's the one who knows 3NT is not an option's job to start looking for it.

If that's opener, you have the advantage that it "can't be" a self-supporting long suit (although some will open on 6m322), so with no fit, responder is free to continue the scramble.

If it's responder, there's a chance that "stopper for 3NT" overrode any thought of stating their suit (less so in Rubensohl, of course, which will always get another call) so opener has to be more wary of pulling. But opener "should have" at least xx in the suit, so responder is more likely to be able to place the contract.

Like anything, "preempts work™" sometimes, even at the 2 level. It's possible that the last making contract is only available in the rear-view; it's possible that a poor suit will be trump with a much better one available that you would have found if it weren't for the pesky opponents telling each other what to lead. It's also possible that the interference is the only way to avoid the doomed 3NT and any plus score is a win!

I am not a Rubensohl specialist (so if those that are disagree with me, listen to them!), but traditionally in these auctions, you "concede" the invitational call opposite the tightly limited hand to the interference; therefore second bids are "looking for the best game". I would expect that any invitational call will be *clearly marked* in the notes, in fact.

[DavidKok]

There are several different versions of Rubensohl. The page you linked is, in my opinion, not fully coherent. I'll give an overview of how I think of Rubensohl. However, keep in mind that there are different ways to play this.

If partner opens 1NT and our RHO overcalls, there are three popular gadgets for handling the situation: Lebensohl, Rubensohl and Transfer Lebensohl.

• Lebensohl uses the 2NT bid as a strength distinction. Direct bids above 2NT are strong (there are some different versions here), while 2NT is a catchall containing all hands that wish to compete at 3-in-a-suit-ranked-below-the-overcall. In addition, there are some exceptional strong hands in 2NT as well.
  
• Rubensohl uses 2NT and up as transfer bids. This shows shape immediately: 2NT always contains clubs (unless that's the opponents' suit), 3♣ diamonds, etc.
  
• Transfer Lebensohl combines the two, but I'll ignore this for now.

The main difference between Rubensohl and Lebensohl is that, in Rubensohl, the transfer bids to lower ranking suits are assumed weak until proven otherwise. The transfer bid of 2NT through transfer-to-the-suit-below-the-overcall do not convey strength. Opener normally completes the transfer, and if responder happened to be strong they can bid again. This second bid is forcing to game - there is no room for invitational bids in lower ranking suits. As an example, let's say partner opens 1NT (15-17), RHO overcalls 2♥, and you hold ♠Qxx, ♥xx, ♦Jx, ♣KQxxxx. You can bid 2NT to transfer to clubs, but partner will assume that you hold a weak hand. If you bid 2NT and bid again, this is forcing to game. Either way, you'll have to make the decision right now. In return you get to clarify your clubs hands better. This is also why I am confused by the link you cite on Rubensohl, which stresses superaccepts. Some of the example hands given there are, in my opinion, unsuitable for superaccepting if partner can be weak.
Note that you do have an invitational bid in suits ranking higher than the interference (as is the case for Lebensohl and Transfer Lebensohl). If you wish to compete in such a suit you simply bid it at the 2-level. Therefore all ways to show that suit at the 3-level are invitational or stronger.

Now, answering your questions:

Knurdler, on 2025-August-28, 13:26, said:

After 1NT (2D) … apparently 3 spades by responder is a transfer to 3NT without a diamond stop (and denies 4 hearts).
What does opener do if they also lack a diamond stop?

As mycroft said, now you being to scramble. Responder has denied 4 hearts and also denied 4 spades, and also denied a diamond stop. This is a scenario no convention handles well - if we have the combined hand strength for game but no major suit fit and a wide open suit so we can't play 3NT, we should try our luck in a(ny) suit at the 4-level. Do notice that this is a property of the combined hands, not of the bidding gadget!
Personally I actually think this scenario is so uncomfortable that I abandoned most of the stopper showing and asking bids. If you can only handle a positive answer, there is no point in using an asking bid. However, this particular stopper denying bid is better than most, and if you manage to find a playable strain at the 5-level that is a nice pickup.

Knurdler, on 2025-August-28, 13:26, said:

After 1NT (2H) … apparently 3 diamonds by responder is a special purpose transfer to the overcaller’s suit.
I understand this bid is a game force and asks opener if they have 4 spades and does not promise a heart stop.
With 4 spades, opener can bid 3 spades.
Without 4 spades but with a heart stop, opener can bid 3NT.
Apparently, without 4 spades and without a heart stop, opener completes the transfer and bids 3 hearts.
Now what does the responder do?
If they have a heart stop, they can bid 3NT.
But where can they go without a heart stop?

Again, as before, you need to scramble at the 4-level.

Knurdler, on 2025-August-28, 13:26, said:

After 1NT (2H) 2NT (P) 3C … I understand that responder can pass if weak.
Responder can bid 3 spades to show 6 clubs and 4 spades – is this invitational or forcing?
Without 4 spades, what does responder need to bid 3NT?
My guess is 10 points and a half heart stop?

It is forcing to game. I think it is standard that a 3♥ bid here asks for a heart stopper, while 3NT instead promises it.

Knurdler, on 2025-August-28, 13:26, said:

After 1NT (2H) 3H (P) 3S … Apparently responder with only 5 spades can bid 3NT.
Does this suggest responder has 10+ points?
How can responder bid 3NT without a heart stop?
Another site suggests that responder can pass 3 spades. Does that suggest the 3 heart transfer bid only needed 8-9 points?

3♥ here is invitational or stronger, starting at around 8 points. Weaker hands will bid 2♠ (competitive). Opener can superaccept with a maximum suitable for spades (4♠) or unsuitable for spades (3NT), and some may jump into control bidding instead with spades-suitable hands. The transfer complete of 3♠ instead shows a minimum in context, and responder can pass with the invitational hand or bid on with the game forcing hand. There is no room to show or deny a heart stopper in addition to the five spades, so opener just has to pass 3NT even without a stopper and hope for the best.