[cargobeep]

2NT in SAYC normally shows 21-22 HCP and a balanced hand. That's all nice and all, but...


1) Opener can reverse bid instead (1♦ - 1♠, 3♥)
2) Opener can open 2♣, and adjust the range a bit.

Personally, I usually just open 2♣ with 20+ HCP, and this allows me to stick other meanings to a 2NT opening bid instead.

So why use it?

[hrothgar]

 cargobeep, on 2012-October-03, 12:22, said:

2NT in SAYC normally shows 21-22 HCP and a balanced hand. That's all nice and all, but...


1) Opener can reverse bid instead (1♦ - 1♠, 3♥)
2) Opener can open 2♣, and adjust the range a bit.

Personally, I usually just open 2♣ with 20+ HCP, and this allows me to stick other meanings to a 2NT opening bid instead.

So why use it?

Because it makes it so much easier to find minor suit slams...

On a more serious note, most systems have rather strict shape requirements for a reverse.

An auction like

1D - 1S
2H

unambiguously promises longer Diamonds than Hearts. No good comes from reversing with balanced hand patterns.

Natural 2NT bids aren't that popular. The 2NT opening is often called "The Slam Killer" because its so difficult to exchange information after this opening. With this said and done, its unclear that increasing the HCP range for 2C - 2X - 2N is any better.

[billw55]

 cargobeep, on 2012-October-03, 12:22, said:

1) Opener can reverse bid instead (1♦ - 1♠, 3♥)

This sequence is not a reverse. 2♥ by opener would be the reverse, as hrothgar says. 3♥ is something else, to be agreed with your partner. Personally I would consider it a minisplinter, showing spade support and heart shortness. There may be other uses as well.

[ArtK78]

Besides the fact that other sequences tend to show unbalanced hands, the main reason for using a 2NT opening bid in SAYC as 21-22 is so that all ranges can be covered with a minimum of artificiality.

[By the way, I believe you mean 20-21, not 21-22. I don't know of anyone who plays a 2NT opening bid as 21-22 in a standard structure]

The typical way to show various strength balanced opening hands in SAYC is as follows:

12-14: Open one of a suit and rebid 1NT.
15-17: Open 1NT.
18-19: Open one of a suit and jump rebid 2NT.
20-21: Open 2NT.
22-24: Open 2♣ and rebid 2NT.
25-27: Open 2♣ and rebid 3NT.

Again, this is how it is done in SAYC. I am assuming that a 3NT opening bid is not some sort of strong balanced hand.

Most partnerships will have found other ways to cover the various ranges which differ from the above.

You propose opening 2♣ and rebidding 2NT with 20-21 HCP. That is all well and good, but then you will have to come up with ways to show the stronger balanced hands, and you are going to run out of room real quick if you reserve that sequence for 20-21 HCP. You will have to add some artificial sequences (Kokish comes to mind) to show higher ranges.

[blackshoe]

SAYC defines the 2NT opening as balanced 20-21. If you play it as something else, you are not playing SAYC.

In most Standard American variants (including 2/1) the 2♣ opening is already too busy to be asking it to do more.

[TylerE]

Also, opening 2♣, as a rule, is the worst opening your side can make - it tells little about openers hand and starts the auction at a high level (you're often at the 3 level before you start showing suits). You should endeavor to open 2♣ as little as possible.

[P_Marlowe]

Depending on the rest of your system - putting to many hands into 2C, makes it harder
to find out, what hand are contained in the 2C bid.

Reducing the strength requirement for a 2C, makes it harder to defend, if the y overcall
our 2C opener.

This being said, ..., if you think the other options are more useful, than this disadvantges
you get, than why not, it is no longer SAYC, what you are playing, but ok.

With kind regards
Marlowe

[lycier]

I think there are many confusions in those knowledges.

Now let's analysis at below.

1- What is the principle of reverse bid?

Reverse bidden by opener is a hand in which have something with a voluntary reply of responder.

When a voluntary reply is received,the combined values known to opener can equal those suggested for game,so it is forcing a round.

2- What is the principle of opening 2♣?

Opening strong 2♣ show a hand in which have nothing with responder's hand,it suggests values so strong that games chances are likely opposite virtually nothing in responder's hand,so 2♣ opening bid forces a reply.



3- What is opening 2nt?

It is a descriptive bid without forcing a round,merely.

As to 20-21hcp with the balanced hand,can it be able to creat any game automatically? or equal to game?

The answer is No.

[awm]

There are some advantages to the 2NT opening. It offers a very good description of opener's hand. For example:

(1) If you open a natural minor on these hands, you will often have a more revealing auction. Compare 2NT-3♥-3♠-3NT-Pass against 1♣-1♠-2♥-2♠-3NT. In the first auction all you know is that responder has five spades and opener prefers notrump. In the second auction you know opener's longer minor (clubs) and that opener has four hearts, as well as responder's spade holding. Good defenders can make use of this information.

(2) Sometimes opponents can get a bid in. For example compare 2NT-3♣-3♦-3NT uncontested against 1♣-Pass-1♥-1♠-Dbl-Pass-2♣-Pass-3NT-All pass. Opener's LHO has a much better chance to "hit partner's spade suit" on the lead with the second auction!

(3) Reverses become more informative. For example, playing standard methods the auction 1♣-1♠-2♥-2♠-3♠ promises a singleton or void diamond. Opener has shown five clubs, four hearts, and three spades after all! But if opener would bid this way on a strong 3424 or even maybe 3433, this information is lost. It can help a lot in slam bidding to know more about opener's shape.

(4) Responder can just sign off in 4M with six. For example, it's much easer to bid 2NT-4♥ (transfer) - 4♠ than to guess over 1♣-1♠-2♥-2♠-3NT, which will often be a strong 1435 (where you don't want to rebid a weak six-card spade suit a third time).

(5) You can sometimes suppress a four-card major, bidding 2NT-3NT (for example on a 4333). This can reach a better contract as well as producing a less informative auction. Opposite a one-minor opening you basically have to bid your major (because opener could have a shapely hand where the major suit is much better than notrump).

[Zelandakh]

You missed another one Adam - it removes an awkward hand from barrage auctions. The classic is 1m - (2♠) - P - (3♠) where Opener holds a balanced 20 count with 3 small spades. Some pairs play a Mexican 2m opening to get the balanced 18-19 hands out of 1m - how much worse is it when all the balanced 18-21/22 hands are bundled in?