[mike777]

Roland may be correct in what is the standard meaning of two way checkback. I must admit I only learned the version where 2clubs is not an auto puppet to 2D with 3 card support.

The Official Encyclopedia of Bridge 2001 does not address the question.


Miles discusses it in Modern Constructive Bidding 2005. He points out how many experts saw a flaw in that method and do not play 2c as an autopuppet. With all of that said Roland may be correct in what is the generally accepted definition.

It appears BWS does not play 2 way checkback from what I could tell.

I admit that is all you find in old Google articles.

[kenberg]

We have the link now for chkbck. Thanks, Roland. Is there a comparable link for an extensive version of nmf?

I may or may not go to the effort, and get partner to go to the effort, to master chckbck, but I am very aware that nmf, at least in the simple version I play, has it's potential for problems. The fact that I may not bother is basically irrelevant (except to me). The poster asked for a serious comparison and so far it seems the field belongs to chckbck. I would like to see a comparably sophisticated write up of nmf before declaring a winner however. Even if nmf, in iots full form, can't measure up to chckbck, in its full form, an extended nmf might still be a viable choice for many if it still offers simplicity. Right now what I play is defnitely simple, and I just hope the disasters don't happen. They usually don't. But one could do better.

[mikestar]

XYZ is 2-way checkback, but extended to all cases where bids X, Y, and Z are at the one level--opener's rebid need not be 1NT.

[kenberg]

luke warm, on Jul 3 2006, 03:18 PM, said:

P_Marlowe, on Jul 3 2006, 01:15 PM, said:

Not 100% sure what the given auction shows, but playing NMF or no convention at all:

1h : 1s : 1nt : 2nt : pass

With kind regards
Marlowe

you and arend are right, my point (hazy as it was) was to show that any minor suit bid, playing nmf, is game forcing.. it's true that the given hand isn't a good example

the link roland gave is excellent, but his write-up on his 2/1 page is far better, imo...

go here: roland's write up and just register.. then click 'lessons' and, on bottom right, 'all articles'... then scroll to the 2 way article... great write up and shows, imo, the power of the convention

"Any minor suit rebid is game forcing in nmf?" Are you talking about your auction 1H-1S-1N-2C? That is not game forcing in nmf as I play, nor have I ever seen it played that way.

1H-1S-1N-2C-2D-3D is game forcing with most people, I think. Going through new minor and then bidding at the three level is usually played as gf.

As mentioned earlier, there obviously is less than total agreement on what all the terms mean. It would be really good to see a nmf website comparable to the chckbk one. The way I play nmf is: after 1x-1y-1N, any immediate jump rebid to the three level is invitational. Any sequence going through new minor and then bidding at the three level is game forcing. It works pretty well most of the time. I imagine there is a more sophisticated approach, but I lack a reference. With some partners there are exceptions, for example 1C-1S-1N-3H is probably thought of as forcing with many, and I can play it that way. But my preference, for ease of memory, is the dichotomy I mention.

[neilkaz]

I've played nmf for about 18 years here in the US, but am not terribly familiar with checkback or xyz, so I took a real good look at Roland's fine 2/1 site.

A couple difference with weak hands are :

1) NMF allows the opening pair to end in 2C after 1C-1M-1N-2C sign off. (However for that to be best, the opps must not balance profitably in one of the two unbid suits, and if they do and you bid 3C it must get set.)

2) NMF allows opener to rebid his 5 card D suit with a non supporting min, incase 2D is the best contract (not terribly often) .. ie 1D-1M-1N-2C-2D shows 5 D's, a min, and denies a 3 card major or 4 cards in the other major.

2WCB allows one who plays Walsh responses (not my style) to get out with in a weak 6 card D suit just by passing the forced 2D. (Not terribly common, and once again the opps may balance in the 4th suit, and/or 3D may make)

However, the nice feature of 2WCB is the force to game at a low level using 2D. Now opener can bid his pattern, and that can be useful for slam and also useful when there's no stopper somewhere and the game to be played must either be a 5-2 or 4-3 fit.

A couple of questions for Roland, etc.

What differences exist between direct 2N invites and 2N invites that use the 2C relay first ?

I know the Turkish players commonly play checkback. The French play Roudi. I found a site that can be translated into English that explains Roudi, but I have never found a site that explains standard Turkish bidding and how they play checkback. Can someone link me to a translatable site that covers standard Turkish bidding ? (also their multi 2D and 55 2H and 2S bids).

OK back to the question de jour... I have to admit that I now prefer 2 Way CheckBack to NMF. .. neilkaz ..

[Walddk]

neilkaz, on Jul 5 2006, 05:59 AM, said:

A couple of questions for Roland, etc.

What differences exist between direct 2N invites and 2N invites that use the 2C relay first ?

Different approaches here. Some play a raise to 2NT as a relay to 3♣ with various continuations. My preferred method is.

1. Direct 2NT: natural with little or no help in opener's minor.
2. 2NT after 2♣ first: natural with significant help in opener's minor; at least 1 top honour to three.

Examples:

1♣ - 1♥
1NT - 2NT

Natural invite (11-12). Little or no help in clubs.


1♦ - 1♠
1N - 2♣
2♦ - 2N

Natural invite (11-12) with significant help in diamonds.

Sometimes this is very helpful for opener to evaluate his hand. This for example:

105
KQ4
AQ864
J87

This is a minimum which would likely pass a quantitative 2NT. However, if you know that partner has Kxx diamonds, you also know that you have a source of tricks. You should now raise to game.

Roland

[1eyedjack]

neilkaz, on Jul 5 2006, 04:59 AM, said:

1) NMF allows the opening pair to end in 2C after 1C-1M-1N-2C sign off. (However for that to be best, the opps must not balance profitably in one of the two unbid suits, and if they do and you bid 3C it must get set.)

I tend to find that it pays to go straight to 3C if you believe that it is right to remove NT to C. Give oppo the last guess at 3 level. It is possible that NMF allows you to do this, I don't know, but CHB does (at least the way I play it). Anyway, signing out in 2C even if available becomes a bit redundant once that (committing to 3 fast) becomes your policy.

neilkaz, on Jul 5 2006, 04:59 AM, said:

2WCB allows one who plays Walsh responses (not my style) to get out with in a weak 6 card D suit just by passing the forced 2D. (Not terribly common, and once again the opps may balance in the 4th suit, and/or 3D may make)

It is a bit more common. Say the opener is 1D and you have 4-6 in Spades and Clubs respectively but not enough for a 2/1 response. It is nice to sign out in 3C after 1D-1S-1N. Perhaps NMF also allows this.

neilkaz, on Jul 5 2006, 04:59 AM, said:

However, the nice feature of 2WCB is the force to game at a low level using 2D. Now opener can bid his pattern, and that can be useful for slam and also useful when there's no stopper somewhere and the game to be played must either be a 5-2 or 4-3 fit.

In my preferred variation, responder gets to choose who is captain. Rather than start with 2D on all GF hands he starts with 2D only on those GF hands that he wants to captain (opener initially assumes invite, and describes accordingly). With a distributional GF hand responder may be better off describing his own hand, shortages etc, so that opener can re-evaluate the working potential of honours. So we use a variety of 2C puppet and 2S+ puppets for responder to describe GF hands.

The weakness in CHBK (at least the way that I play it) is when responder has a weak 2-suiter where the second suit is not Hearts. To a lesser extent you can also have a problem with an invitational 2-suiter and, depending on how the auction develops after 2D, perhaps inability to show the second suit.