[jillybean]

I think I know the answer to this, but here's the question anyway.

1♠:2♦
3♦:

2♦ is GF, 3♦ agreeing ♦

Playing A,K,singleton,void style of cue bidding can I use 3nt here to show slam going control in "other 2 suits", or is it more valuable to have a natural 3nt available?

[Cyberyeti]

I wouldn't use it for that, just bid 3♥ and see if partner bids 3♠. Natural 3N is a likely resting place.

In other sequences, 3N is better used as either serious/frivolous or as we use it, the most expensive cue bid (ie hearts agreed, partner cues 3♠, 3N is a spade cue).

[ali quarg]

 Cyberyeti, on 2021-February-24, 04:42, said:

I wouldn't use it for that, just bid 3♥ and see if partner bids 3♠. Natural 3N is a likely resting place.

In other sequences, 3N is better used as either serious/frivolous or as we use it, the most expensive cue bid (ie hearts agreed, partner cues 3♠, 3N is a spade cue).

3NT can be used to deny 2 of the top 3 majors when you have bid trumps first or 1 of top 3 when supporting. If 3NT is bid it could be passable if suit strength is deficient

I've also seen the suggestion that bypassing X (X<>1) number of suits indicates control in those suits. This may be more flexible

In the above case given you haven't bid 3NT immediately I guess you could use 3NT to show control in the other 2 suits, but does 3NT say something about trump controls as well?

[pescetom]

 jillybean, on 2021-February-24, 02:37, said:

I think I know the answer to this, but here's the question anyway.

1♠:2♦
3♦:

2♦ is GF, 3♦ agreeing ♦

Playing A,K,singleton,void style of cue bidding can I use 3nt here to show slam going control in "other 2 suits", or is it more valuable to have a natural 3nt available?

I don't think that playing this auction as a definitive fix of trumps in diamonds and 3NT as something artificial makes much sense in general. Just because you have fit in the minor (and it makes sense to show 3+ cards if 2♦ promises 5+) does not meen you can afford to exclude a natural 3NT, which as CY says is often the best resting place here. 3♥ should be natural here too. If 2♦ does not deny fit in spades (which is also a useful agreement) then 3♠ must over-ride the fit in diamonds and fix trumps in spades, inviting a cuebid. 3NT should be natural NF, but partner with good reason will bid on.

In particular if you want to play Italian style mixed cuebids (A,K,singleton,void), then I think it makes more sense to avoid them below 3NT when the fit is in a minor, as Italians themselves do. So you might have an auction like:
1♠:2♦
3♦:3♥
3NT:4♣
4♠:5♦
p
Opener showed fit in diamonds, responder showed hearts, opener made a natural proposal of 3NT (suggesting a clubs stop), responder re-opened with a cuebid showing clubs control and fixing trumps in diamonds, opener showed control in spades denying hearts, responder with no hearts control put on the brakes.

And there is no need for a bid showing control of two or more suits, as CY said, just follow the rules and cuebid your cheapest control.

[blackshoe]

I prefer "control bid" to "cuebid" in this context. And I prefer that after minor suit agreement below 3NT the protocol is primarily to look for game in NT. So after 1♠-2♦-3♦, 3♥ is ambigous, primarily showing a stopper for NT purposes, but possibly a control bid, which will be evidenced if opener continues over responder's 3NT. 3♠ by responder instead of 3♥ would be natural, showing a fit. 3NT would suggest playing there, with stoppers in the round suits.

Opener's 3NT after responder's 3♥ would be to play. 4♣ would be a control bid, which suggests that 3♥ was also a control bid. So either we're stopping in 5♦ or we're getting to slam.

[pescetom]

 blackshoe, on 2021-February-26, 13:25, said:

I prefer "control bid" to "cuebid" in this context. And I prefer that after minor suit agreement below 3NT the protocol is primarily to look for game in NT. So after 1♠-2♦-3♦, 3♥ is ambigous, primarily showing a stopper for NT purposes, but possibly a control bid, which will be evidenced if opener continues over responder's 3NT. 3♠ by responder instead of 3♥ would be natural, showing a fit. 3NT would suggest playing there, with stoppers in the round suits.

Opener's 3NT after responder's 3♥ would be to play. 4♣ would be a control bid, which suggests that 3♥ was also a control bid. So either we're stopping in 5♦ or we're getting to slam.

Which is very much what I said too, except that you allow 3♥ to be possibly a control bid - which ironically was the traditional Italian agreement, although now out of fashion.