Gazilli vs transfers

[DavidKok]

Rather than 'more complex', I think 2-way bids are usually just inferior to 1-way bids because of this issue. In my experience they only work well in very specific situations. The simple (and boring) 2-way bids are all just split range with the same shape, because responder's hand will evaluate the same opposite those regardless.

[mw64ahw]

Started some simulations.

The first hand was exactly as above with a 3♠ bid required showing a minimum and short ♣ so as to be in the optimum makeable contract rather than 3♣

[mw64ahw]

I've played around with a few simulations given the proposed structures above and come up with a couple of further options.

 

The key elements in these options are:

• 2/1 bids are game invitational rather than game forcing
• semi-forcing NT with all Weak balanced hands passing. Good 14+ balanced hands should be are included in the 15-17 NT
• responder doesn't usually play in 1NT with a long weak suit with the exception of ♣
• responder doesn't usually play in 1NT with 9-10 and any long weak suit
• openers game invitational bids in a 2nd suit are shown via 2NT rather than using the Gazzilli approach and stopping in 2M. 3♣ by responder now becomes a game force.
• opener's game forcing bids are shown via 3♣ and higher bids that describe shape
• ♠ support bids are as comprehensive as I can get with regards to strength
• transfer breaks have been simulated with reasonable results which appear to help in slam bidding (details not included)

1st Option: Responses after 1♠ opening

• 1NT 6-10
• 2♣ 3+♣ 11+ or 3+♣3♠ GF or 6+♦ Weak or 6+♦ 9-10
• 2♦ 5+♦ 11+ or 2♣3+♦3♠ GF or 6♥ Weak or 6+♥ 9-10
• 2♥ 5+♥ 11+ or Constructive 3+♠ or 3♠ Limit Raises
• 2♠ 3/4♠ Pre-emptive
• 2NT 4+♠ Limit+
• 3♣ 6+♣ 9-10
• 3♦ Stronger 4+♠ mixed raises
• 3♥ Weak 4+♠ mixed raise
• 3♠ Pre-emptive
• 3NT 13-16 (3433)
• 4♣ SI ♣ void
• 4♦ SI ♦ void
• 4♥ SI ♥ void
• 4♠ Pre-emptive

Rebids after 1NT response

• Pass Balanced 11-13/14
• 2♣ 4+♣ 17+ or 4+♦
• 2♦ 4+♦ 17+ or 4+♥
• 2♥ 4+♥ 17+ or 6+♠
• 2♠ 5+♠ 4+♣
• 2NT 18-19
• 3!♣ good 5+♣♠ 14-16
• 3♦ good 5+♦♠ 14-16
• 3♥ good 5+♠♥ 14-16
• 3♠ good 6+♠ 14-16
• 3NT 18-19 no weak doubleton

With 2♣-2♥ after responder has shown a preference 2NT now shows the game invitational hand while higher bids are game forcing and show shape.

2nd Option

This follows the broad structure above with the following exceptions

• Responder may stop in 2♣ as in http://www.bridgematters.com/idea3.htm
• 1♠-1NT-2♠ now shows 5+♣♠ as in http://www.bridgematters.com/idea3.htm
• 1♠-1NT-2NT is either 17+ 5♠4+♦ or 5323 18-19 with a weak ♦ doubleton
• 1♠-1NT-2♦ now shows ♣ as the strong option or 5332 18-19 with a weak doubleton
• 1♠-1NT-2♥ now shows ♥/♠ as the strong option or 5232 18-19 with a weak doubleton

[DavidKok]

Sorry, I don't get it. Quite a few of those key elements sound like weaknesses? 2/1 is no longer GF so you lose accuracy on game auctions, responder's game force starts at the 3♣ level, opener starts showing shape with GF hands at the 3♣ level, the first round bids contain many different hand types both in terms of shape and strength so you're vulnerable to interference. What are the benefits of this approach?

[mw64ahw]

Sorry, I don't get it. Quite a few of those key elements sound like weaknesses? 2/1 is no longer GF so you lose accuracy on game auctions, responder's game force starts at the 3♣ level, opener starts showing shape with GF hands at the 3♣ level, the first round bids contain many different hand types both in terms of shape and strength so you're vulnerable to interference. What are the benefits of this approach?

I guess the best way to test the structure is to try it in practice rather than just simulate since at the moment this is just an academic exercise

 

Your points

 

a) 2/1 GI vs GF is a question of style. As you are aware there are benefits to GI. At least with GI you can exclude any balanced hand rather than having a 13-14 balanced hand sitting there with a semi-forcing NT

b) With Gazzilli I guess opener doesn't get to show their 2nd suit with 17/18 and responder not showing 8+.If they do then its at the 3-level? In option 1 you know both the strength and the 2nd suit at 2NT. I've seen hands where having this definition will get you to 3NT with less than 8hcp if you apply the correct judgement

c) Responder can GF after a 2NT response knowing both opener's precise strength and 2nd suit so:

1♠-1NT

2♥-2♠

2NT shows 17/18 5+♠4+♥xx - 3♣ (as an option) then asks opener to define further, say

--3♦ <Default>

---- 3♥ asks 55xx, 5422 etc.?

--3♥ 5413

--3♠ 64xx

--3NT 5431

--4♣5404

--4♦5440

--4♥ 6♠5♥

If you can't place the contract from there then this is not the approach for you

 

d) You are correct that responder's bid can be subject to interference, more so with the weak option. However, I don't think this is any different from any other approach where you may get interference. With interference your methods change. The benefit is that you don't get stuck in 1NT with a long minor suit and weak when opener passes. The bid in the weak case is also more pre-emptive than 1NT where something like a Vasilevsky defence can be applied. And woe betiede opponents who X when you have the stronger options. I do run simulations with and without interference and defence becomes trickier with the mulri from my limited perspective.

 

1♠-P-2♦ ♣ interference is now at the 3[level]

1♠-P-1NT-X as ♣

[DavidKok]

The issue with interference on multi-way bids is that is can be difficult for opener to evaluate their hand without a clear cue on what responder might have. For example, on the first option 1♠-(P)-2♥-(3♦); <some bid>-(4♦) might be problematic since opener doesn't know about support, and might not have a safe bid over 3♦ if partner has hearts, while responder can't safely bid at the 4-level over what is potentially a minimum. The more the weak and strong options differ in shape the worse this problem is (the 2♣ response in particular is vulnerable to this).

[mw64ahw]

The issue with interference on multi-way bids is that is can be difficult for opener to evaluate their hand without a clear cue on what responder might have. For example, on the first option 1♠-(P)-2♥-(3♦); <some bid>-(4♦) might be problematic since opener doesn't know about support, and might not have a safe bid over 3♦ if partner has hearts, while responder can't safely bid at the 4-level over what is potentially a minimum. The more the weak and strong options differ in shape the worse this problem is (the 2♣ response in particular is vulnerable to this).

I think you have plenty of options here:

Pass - partner will bid ♠ with 3+ (possibly passing VN with a weak constructive bid), X for penalty, bid 3♥ with 6♥ or 3NT with a GF hand and ♦ stopper

X Penalty without ♥

3♥ 5+S♠3+♥ enough for 3♠ or GF ♥

3♠ 5+S♠3+♥ GF in either contract

3NT ♦ stopper with 17+

4♦ SI in either contract

4♠ self-sustaining suit