[Kungsgeten]

In this Bermuda Bowl, I noticed two dutch pairs playing the 1C opening as natural / weak NT / strong NT (so standard 5542). Over this, they used the following 1D response:

a) Any weak hand, 0-6. I guess the idea is to make the other responses GF vs the strong NT.
b) 7-10 with 4-4 majors. So less than invitational vs the weak NT. The reason must be so that 1C-1H; 1S promises an unbalanced hand.
c) Natural, usually no major (Walsh-style). I may be wrong though, it could be that they always bypass diamonds with 4M.

Then the following auctions are listed:

1C-1D; 1H = Clubs + hearts, or weak NT.
1C-1D; 1NT = Strong NT.
1C-1D; 1H-1S = Relay.
1C-1D; 1H-1NT = 4-4 majors.

Does anyone know more details about this treatment? Especially about how opener bids when strong and unbalanced (and how responder should act when really weak), but also how responder bids when he has diamonds. For instance:

1C-1D; 1H---
1S = Relay. Which strong/weak hands are included?
..1NT = Weak NT. Now what? Can the weak hand sign off? Perhaps weak/strong transfers?
..2C = Limited with clubs and hearts? What is the maximum?
..2X = Stronger with clubs and hearts?
1NT = 4-4 majors, 0-10 hcp. Perhaps weak hands with say 4H and 5S bids this too? Does opener's 1M bid have a limit (if unbalanced), or is it 11-22?
2C = My guess is that this shows both minors, but no idea about what kind of strength. Another option could be something artificial with diamonds, and GF.
2D = Natural? But what tempo?
2M = ??

Here's the convention cards:

- http://www.ecatsbrid...ankveldREV2.pdf
- http://www.ecatsbrid...Drijver_Nab.pdf

[Zelandakh]

This might be of some use to you in deciphering the rest...

[Kungsgeten]

Zelandakh, on 2017-September-06, 05:49, said:

This might be of some use to you in deciphering the rest...

Thanks! There's not much details about the sequences I mention above though. They seem to use the NT-system after 1C-1D; 1H-1S; 1NT.

[steve2005]

Also, they are using different NT ranges depending on seat and Vul, so makes it difficult even with full writeup to figure out whats going on.

[helene_t]

These sequences were described in details (in Dutch) in the IMP magazine, http://www.imp-bridg...t-hele-systeem.

Unfortunately I only had two suitcases worth of allowance when I moved to New Zealand but maybe you can find a Dutch friend who has a copy? Most serious Dutch/Flemish bridge players subscribe to IMP.

[Wouterf]

Ik dont have the system in writing but I can help a bit with the follow up.

1C = 2+ crd, natural or 12-14nt without 5crdM or D, or 18-19bal (this one can have 5crd D)
(when 1NT is 10-12 or 12-14, then the weak bal becomes 13-16 or 15-17, strong is always 18-19 and sometimes 18-20)

1C-1D; 1H = Clubs + hearts (unbalanced, could be 4414or1444shape), or weak NT.
1C-1D; 1NT = Strong NT (18-19bal can still have 5D).
1C-1D; 1H-1S = Relay.
1C-1D; 1H-1NT = 4-4 majors (0-10hcp).


1C-1D; 1H---
1S = Relay. Which strong/weak hands are included?
- Pretty much every strong hand, hands that pass 1NT and very weak ones with 5crdM(0-6)hcp

..1NT = Weak NT. Now what? Can the weak hand sign off? Perhaps weak/strong transfers?
- The game continues as if p opened 1NT, so stayman and tranfers (very weak 5M transfers).

..2C = Limited with clubs and hearts? What is the maximum?
- 2 weak for a reverse, so 11-15ish

..2X = Stronger with clubs and hearts?
- Yes, usually paterning out, bidding a 3crd spade or diamond suit or 4441type shape 16+hcp.

1NT = 4-4 majors, 0-10 hcp. Perhaps weak hands with say 4H and 5S bids this too? - Usually 4-4 only. Other option is 2 simply relay and bid stayman after 1NT (garbage stayman) or jacoby transfer.

Does opener's 1M bid have a limit (if unbalanced), or is it 11-22?
- 11-22

2C = My guess is that this shows both minors, but no idea about what kind of strength. Another option could be something artificial with diamonds, and GF.
- This tends to just show 5 clubs and 0-6

2D = Natural? But what tempo?
- Diamonds natural and weakish, TP versus 12-14bal so 0-9hcp

2M = ??
- Doesnt exist, but I have seen some agreements as shortness and invite+ or weak with both minors.

Some further details: a 2NT rebid by opener after 1M shows 3M6m or 4M5m and strong. so
1C-1H-2NT= 16+ with 5+Cand3-4H
1C-1H-2D= either a normal reverse, or 18-19bal
1D-1M-2NT= also 16+with 5+D and 3-4M.
This is the reason why all 18-19bal are opened with 1C (and can still have 5D)

[Kungsgeten]

To me it is a bit strange that responder doesn't just pass with a very weak hand and 5+ clubs, but perhaps that makes it too easy for the opponents.

[helene_t]

Kungsgeten, on 2017-September-07, 08:25, said:

To me it is a bit strange that responder doesn't just pass with a very weak hand and 5+ clubs, but perhaps that makes it too easy for the opponents.

Some people do. In that case you don't need a way to show 0-4 points with long clubs after having responded 1♦. But also some people include some GF 4441 hands in the 1♣ opening.

Actually, I think making it 100% forcing makes it easier for opps. They can afford to pass with strong hands and then have the agreement that pass followed by action is strong than direct auction. In particular, if they hold a natural 1NT overcall they just pass. Bidding 1NT in the second round is safer once LHO has bid 1♦ which essentially says that he is unlikely to double 1NT.

I suppose they "should" play the same defense against a semi-forcing 1♣ opening but it is not obvious.

[Wouterf]

Kungsgeten, on 2017-September-07, 08:25, said:

To me it is a bit strange that responder doesn't just pass with a very weak hand and 5+ clubs, but perhaps that makes it too easy for the opponents.

Well in matchpoint bidding 1D can be very beneficial if partner has the 18-19bal. Auction will often go 1C-1D-1NT (opps dont bid anything so p is often strong), which pays a lot more than 1C. Also (non-vulnerable) bidding might bluff your opps out of their contract.

[DJNeill]

More details about Dutch Doubleton (modern style played by various pros)
https://bridgewithda...bidding-system/