[DavidKok]

A low-information relay would work well here, that is a nice idea. Which hands would choose the strong relay and which would choose the weak relay? I'm a bit concerned that the choice of relay will tell the opps a bunch about our hand. Probably it is a balanced hand or semibalanced hand with spade shortage, not 1=3 or shorter in the majors? Possibly something like 6♣ with interest in a major suit (either 2 spades or 4 hearts). Then again I imagine most opponents won't be aware enough to draw these inferences, even if you volunteer them.

[nullve]

DavidKok, on 2023-November-14, 03:07, said:

not 1=3 or shorter in the majors?

Responder could also be looking for a 5-3 heart fit.

[awm]

Elianna and I play something similar but our 2♣ is not always game forcing (making it essential to be able to get out at times). We do play that 1♠-2♣-2♥ is natural with a wide range, so 2♦ by opener would deny four hearts here. The 2♦ rebid is either any minimum or natural with diamonds (3♦ is natural and extras but should be at least 5-5 and fairly pure).

Bidding 2♦ also denies 6M because we open 2M on 9-13 with a six card major (and bid 2M over 2♣ with 6M and 14+). So it’s fairly common for responder to blast 3nt over the 2♦ rebid without being overly concerned about major fits.

[pescetom]

nullve, on 2023-November-13, 17:57, said:

To reduce the information leakage on hands like this, one could play

1♠-2♣; 2♦-2♥ = strong relay
1♠-2♣; 2♦-2N = (Staymanesque) weak relay, mostly (only?) asking about major suit length

and have an auction like

1♠-2♣
2♦*-2N**
3♣***-3N****
P

* any MIN
** weak relay
*** neither 4+ H nor 6+ S
**** contract

.

Be it this or other I can see that it makes sense to assign some relatively frequent meaning to 2M after a 2D minimum rebid: I was surprised that they don't seem to do this and just bid 2NT automatically as far as I can see.

[Gilithin]

DavidKok, on 2023-November-13, 16:35, said:

You are dealt ♠Kx, ♥Qxxx, ♦Qxx, ♣AKxx. Partner opens 1♠, you are optimistic about slam and bid 2♣. Partner bids 2♦. Slam has become quite remote, but you might belong in any of 4♠, 4♥ or 3NT. So you have to ask for more info (2NT, or 2♥), and partner rebids 3♣. Now 4♥ is out of the picture and you've pinpointed a red suit lead against 3NT, and 4♠ in the 5-2 fit doesn't look great. Are you asking more info (but what for?), bidding 3NT, or something else?
If 2♥ could have been a minimum so that 2♦ denies extra major suit length you could have bid 1♠-2♣; 2♦-3NT, concealing your heart length and possible diamond weakness. More generally, if 1♠-2♣; 2♦ shows any minimum (use any criteria for evaluation you prefer), responder will often have to ask for shape information next with 4 hearts, or a side suit weakness. A lot of the time partner won't have the extra length in a major suit you are looking for, and you end up bidding 3NT anyway but have now partially exposed declarer's hand. One possible remedy is to immediately split out some hands with extra major suit length from 2♦, so that it is no longer any minimum but rather a 'boring' minimum. This allows responder to jump to 3NT or 4M on the second round often.

There are a number of reasons to prefer this relay structure and the given hand is just one of them. It also makes the responses for 1♠ - 2♣ -- 2♠+ and 1♠ - 2♣ -- 2♦ - 2♥ -- 2♠+ identical, reducing memory load. 1♠ - 2♣ -- 2♥ - 2♠ now becomes its own auction of course but relay systems generally have a simple and consistent way of handling 5-4 hand types (aka short-legged two-suiters) so this should not be much of an issue. You are essentially evening out your auctions so that more of them finish patterning out at the same point rather than having several steps between the good auctions and the bad ones.