[gwnn]

You have

AKx
KTxx
xx
Qxxx

All white at matchpoints, LHO deals and it goes

1S-p-p-1NT
2C-2H-3C-?

However, LHO asked your partner what 1NT showed and the answer was '15-17 but slightly wider, say 14-18' whereas you had agreed clearly to play this 12-15.

What are the LA's and what does the wrong explanation suggest? So what do you bid?

[TimG]

I don't think there is a LA to 3♥.

The wrong explanation suggests that partner's upper limit is lower -- he would have made a game try with some hands that would be willing to signoff in 2♥ opposite our agreed range. But, I don't think there was ever a question of bidding 4♥ opposite partner's signoff, so i don't think it is a LA.

[Cyberyeti]

TimG, on 2012-October-24, 17:29, said:

I don't think there is a LA to 3♥.

The wrong explanation suggests that partner's upper limit is lower -- he would have made a game try with some hands that would be willing to signoff in 2♥ opposite our agreed range. But, I don't think there was ever a question of bidding 4♥ opposite partner's signoff, so i don't think it is a LA.

Agreed. He might still bid 4♥ now we've supported, but you're not forced to.

Do you ever pass ? I don't think so, and if you do, it will be ruled back to 3♥ if 3♥ was wrong.

[aguahombre]

What do you know without the UI? You know that you have shown 12-15 balanced and that partner wants to play in two hearts.

What do you know by looking at your hand? You have a nine- or ten-card heart fit and want to bid 3H. So, you bid 3H.

[nigel_k]

It's complicated because there are three possible (not necessarily logical) calls: pass, double and 3♥.

Certainly 3♥ is the normal call, while pass is suggested by the UI. If you decide that double is not a LA, then you adjust if the player passes and that works better than 3♥ would have.

If you decide that double is a LA, it gets messy. Pass could be adjusted to either 3♥ or double, or 3♥ could be adjusted to double or vice-versa. Double is certainly a poor call but people do choose it sometimes in these situations.

[mycroft]

I can't imagine that a minimum with 4-card support for partner's suit will want to bring out double, whatever it means - with AKxx xx KTx QJTx I'd expect that double would likely be the right call.

With the right information, I can't see any alternative to "compete" - I know C players will pass because "I'm minimum and we're clearly outgunned", but that's why they're C players (actually C players will pass because they only have an 8-card (spade) fit, or so they think).