[Laplace0]

What means after the sequence 1-♥-1♠-2♣ a 3♠ bid in 2 over 1. How is a 4 color forcing 2 ♦ to interpret?

[sfi]

2♦ is typically artificial and forcing to game. The meaning of 3♠ depends on the agreement for 1♥-2♠, but the normal meaning is that it is natural and invitational to game.

[Laplace0]

Ok with 3♠. Now 2♦ ask for stopper, show stopper or asks for 3card support in♠

[Stephen Tu]

2 diamonds shows almost any GF hand on this sequence. So it could be based on just about anything, opener shouldn't assume much until hearing responder's 3rd bid.

Opener typically has a priority based on partnership agreement what to show, typical priority is something like:
1. show spade 3 cd support
2. lacking spade support bid NT with stopper 4th suit (jumping to 3nt shows something like 16-17 unbal/semi-bal, bid 2nt then 4nt with 18+)
3. show extra shape features
4. bid cheapest of original suits (here 2H) with nothing more informative to say

[Laplace0]

Fine. I guess this is Hardy-staff. I will use it in the proposed order until some NT contract is missed Thanks all for the comments.

[mikeh]

Laplace0, on 2021-March-12, 13:22, said:

Fine. I guess this is Hardy-staff. I will use it in the proposed order until some NT contract is missed Thanks all for the comments.

It's not Hardy stuff

Hardy was a good tournament director but an indifferent player (at least, in terms of expert players) and his books on 2/1 contained little that was original to him (in fairness, he never claimed otherwise). His first book summarized 'scientific' methods then popular amongst West Coast, primarily Californian, American experts.

As for 4SF, Stephen has summarized the situation well. I would add that it can be useful to think in terms of 'what does 4SF say to me, as opener' to which the answer is:

Based on your bidding and my hand, we have at least game somewhere, and possibly slam. Please make the cheapest descriptive bid you can, following which I will tell you where my interest lies'

Thus:
1H 1S
2C 2D
2H 3C....hey, I love clubs! Let's explore whether we should be in 5C, or 6C or 7C, or 3N, 6N, etc....even 4H is still in the picture

1H 1S
2C 2D
2N 3S....hey, I know you have at most 2 spades and are likely 2=5=2=4 or 1=5=3=4, with a diamond stopper, but I still like my hand for spades...not sure yet where we're going....3N might end the auction, but we're playing spades or notrump, level yet to be determined

And so on.

The part about making the cheapest bid is important, to allow responder as much bidding room, to describe why he is forcing to game or beyond, as low as possible. Requiring a stopper for opener to bid notrump means, here, that 2H, the cheapest call available, might be based on 6=4 hearts/clubs but will often be 5=4.

You need not worry about missing good notrump contracts if, after 2D, neither side can bid notrump along the way (once in a blue moon you miss a 3N with xxx opposite xxx, and they can't run 5 tricks, but it hasn't happened to me in decades)

[sfi]

Laplace0, on 2021-March-12, 13:22, said:

Fine. I guess this is Hardy-staff. I will use it in the proposed order until some NT contract is missed Thanks all for the comments.

The only 4SF auction where this might be a concern is 1H - 1S; 2D - 3C, where you do have to make a choice if opener is something like 1642 with a good club stopper. It's even worse on this auction because opener needs a default bid with something like 2542 and no club stopper, so 3H may not even show 6 - something worth discussing with partner. However, when the fourth suit is at the two-level you should be able to sort out where you belong easily enough.

[Laplace0]

Thanks again. Good analysis showing the importance of 4SF. I used 4SF but with a diverse priority order (first stopper, second 3card support) and missed recently a spade slam. I try now the order you proposed. I think to remember, something similar is described in Hardy's 2over1 book. Don't know which is the originator.

[helene_t]

Whether 3card support has higher priority than a stopper is mood if opener has shown 9 cards in hearts and clubs. With 3 spades also it's only an issue with a stiff ace in diamonds.

[Laplace0]

Actually, bidding 2♣ with 3 clubs happens with regularity.

[helene_t]

Laplace0, on 2021-March-14, 05:29, said:

Actually, bidding 2♣ with 3 clubs happens with regularity.

Yeah good point, with xxx-AQxxx-AQ-Kxx you might decide not to open 1NT, so now you have both a diamond stopper and 3-card spade support.