BBO Discussion Forums: GCC legal T-Walsh substitute - BBO Discussion Forums

Jump to content

Page 1 of 1
  • You cannot start a new topic
  • You cannot reply to this topic

GCC legal T-Walsh substitute

#1 User is offline   nullve 

  • PipPipPipPipPipPip
  • Group: Advanced Members
  • Posts: 1,945
  • Joined: 2014-April-08
  • Gender:Male
  • Location:Norway
  • Interests:partscores

Posted 2015-August-02, 15:51

Judging by the responses to David Loeb's (dloeb's) article

http://bridgewinners...in-a-gcc-event/

on Bridgewinners, it may not be generally known among ACBL members that the scheme

1C-?:

1D = 4+ S
1H = 4+ H
1S = ART GF
1N = nat., NF,

which enables the partnerhip to play something like T-Walsh when Responder has spades, is actually GCC legal. But a comment by Mike Bell (MickyB) points to an even more exciting possibilty: a full-fledged GCC legal T-Walsh substitute. I believe the real idea behind his comment* is that if Responder has some conventional way of dealing with Flannery hands with less than GF values**, then there's no compelling reason why Opener's 1S rebid should promise 4+ S***, so 1S may as well be used as "transfer acceptance" similar to 1M over 1C-1M-1 in T-Walsh. Of course, there's no transfer involved here unless one thinks of 1H as a transfer to the major Responder hasn't promised. (Same with the spade-showing 1D response.)

By combining dloeb's scheme with MickyB's idea, one could play

1C-1OM-1****; ?

1OM: corresponds to 1M over 1C-1M-1 in T-Walsh.
1S = 4+ H
1S(M=S): corresponds to 1S over 1C-1D in the emulated T-Walsh style, but now with 4+ H instead of 4+ S [corrected stupid error 5th August: '1S(M=S)' was just '1S']
1N: corresponds to 1N over 1C-1M-1 in T-Walsh [corrected 3rd August ('1C-1M-1' was '1C-1D')]
2C+: obvious stuff, but depending on the emulated T-Walsh style

But notice that, unlike in T-Walsh, Opener's 1OM/1S rebids are now not easily passable*****, and this could potentially be a huge problem (for more than one reason). But here are three ways to go about it, corresponding to different restrictions one might want to put on Responder's ability to respond 1D or 1H on "air" (as is common when playing T-Walsh).

a) [restrictions on both 1D and 1H] Responder will always have something resembling an inital positive response when he makes his forced rebid, so continuations, apart from the now "impossible" sequence 1C-1OM-1; 1OM/1S-P, may be roughly as in the T-Walsh style one wants to emulate.

b) [restriction on 1H only] Responder is allowed to pass 1C-1D; 1H/1S because of the following variation of the above scheme:

1C-1OM-1; ?:

1H = 4+ H, NF
1S: corresponds to 1M over 1C-1M-1 in T-Walsh, but denies 3-S4+H if M=S
1N+: as above

Continuations, apart from the now "impossible" sequence 1C-1H; 1S-P, may again be more or less as in the emulated T-Walsh style.

c) [no restrictions] Responder cannot easily pass Opener's rebid, so the continuations have to reflect this. E.g.:

1C-1OM-1; 1OM-?:

1S = 4+ H, as above
1N: as in T-Walsh, but could be extremly weak. (Conventional follow-ups may be necessary, depending on the emulated T-Walsh style.)
2C/2H+ = standard XYZ
2D = subminimum, 5+ M******

Any comments?

* "Would 1C:1S as 5H4S be allowed? This would free up 1C:1H,1S to be artificial."
** To be GCC legal, a two-level response (not 1S) has to be used as Flannery, though. An interesting alternative, but which effectively takes the Walsh out of T-Walsh, is to respond 1D, canapé-style, with 4S5+H.
*** Well, Opener may now have to rebid 2C with 4135/4045, depending on the emulated T-Walsh style. But this is the kind of problem that standard or T-Walsh player have with 1435/0445 over 1C-1S and 1C-1H, respectively, but which disappears when the response with 4+ S is 1D instead of 1H or 1S.
**** Yes, the notation '1OM-1' suggests that we may continue to view the 1D and 1H responses as transfers to the other major (=OM), the major Responder doesn't necessarily have. This is convenient when making comparisons with T-Walsh.
***** The same is true of the sequence 1C-1D; 1H-1S, but that seems like a tiny problem in comparison, so I'll ignore it.
****** This is the easiest, assuming Responder would always replay 1S (ART GF) to 1C with 4+ M and GF values. A more advanced version would allow Responder to bid again over 1C-1OM-1; 1OM-2D; 2M(= to play, assuming Responder has subminimal values) on some hands with GF values.
0

#2 User is offline   mgoetze 

  • PipPipPipPipPipPipPip
  • Group: Advanced Members
  • Posts: 4,942
  • Joined: 2005-January-28
  • Gender:Male
  • Location:Cologne, Germany
  • Interests:Sleeping, Eating

Posted 2015-August-02, 17:30

This is incredibly hard to understand... 1OM? 1****? And what's all this "corresponds with T-Walsh"... I mean you do know there are different ways to play T-Walsh, right? Maybe you should just spell it out for us. ;)
"One of the painful things about our time is that those who feel certainty are stupid, and those with any imagination and understanding are filled with doubt and indecision"
    -- Bertrand Russell
0

#3 User is offline   steve2005 

  • PipPipPipPipPipPipPip
  • Group: Advanced Members
  • Posts: 3,069
  • Joined: 2010-April-22
  • Gender:Male
  • Location:Hamilton, Canada
  • Interests:Bridge duh!

Posted 2015-August-02, 19:08

View Postmgoetze, on 2015-August-02, 17:30, said:

This is incredibly hard to understand... 1OM? 1****? And what's all this "corresponds with T-Walsh"... I mean you do know there are different ways to play T-Walsh, right? Maybe you should just spell it out for us. ;)

yes, too hard to follow and I know transfer Walsh

I read the bridge winners seems interesting but didn't go into the details as you are trying for.


Sarcasm is a state of mind
0

#4 User is offline   nullve 

  • PipPipPipPipPipPip
  • Group: Advanced Members
  • Posts: 1,945
  • Joined: 2014-April-08
  • Gender:Male
  • Location:Norway
  • Interests:partscores

Posted 2015-August-02, 20:36

View Postmgoetze, on 2015-August-02, 17:30, said:

This is incredibly hard to understand... 1OM? 1****?

Sorry, didn't mean to use home-grown notation! I was assuming that the notation '1C-1M-1; 1M' is familiar shorthand for '1C-1D; 1H or 1C-1H; 1S', so I wanted to introduce the suggestive(?) notation'1C-1OM-1; 1OM' for '1C-1D; 1H or 1C-1H; 1S' when talking about a T-Walsh substitute where the 1D and 1H responses to 1C show spades and hearts, respectively, i.e. where 1D and 1H can be thought of as "transfers" to the "other" major, the major Responder hasn't shown. I believe the notation 'OM' for 'other major' is widely used, although I have to admit I introduced in a rather unconventional way. For example, I hadn't already introduced the notation 'M' for the known major.

Quote

And what's all this "corresponds with T-Walsh"... I mean you do know there are different ways to play T-Walsh, right? Maybe you should just spell it out for us. ;)

Yes, I know there are different versions of T-Walsh, since I've played quite a few myself. Maybe I chose the wrong title, because I never intended the thread to be about GCC legal substitutes for certain types of T-Walsh only. The OP was intended more as a recipe for turning your favourite version of T-Walsh into something GCC legal without completely destroying its identity. The substitute will no longer be (your favourite version of) T-Walsh, but hopefully something pretty close.
0

#5 User is offline   nullve 

  • PipPipPipPipPipPip
  • Group: Advanced Members
  • Posts: 1,945
  • Joined: 2014-April-08
  • Gender:Male
  • Location:Norway
  • Interests:partscores

Posted 2015-August-07, 12:21

Since my previous post I've discovered a couple of errors in my OP grave enough to render it largely unreadable. I think those are corrected now, but still: Sorry!

A clarification: Since we can take 'T-Walsh' as denoting any structure characterised by

1C-?:

1M-1 = 4+ M, may have longer D if < GF,

let 'T*-Walsh' denote any GCC legal structure characterised by

1C-?:

1OM-1 = 4+ M, may have longer D if < GF

I didn't make it sufficiently clear in the OP, but what I'm dreaming of is a way of assigning to each T-Walsh structure S a T*-Walsh structure S* that is in some predefined sense the closest (GCC legal) approximation to S. (That's how S* can be a GCC legal "substitute" for S and, ultimately, T*-Walsh a GCC legal "substitute" for T-Walsh.)
0

#6 User is offline   blackshoe 

  • PipPipPipPipPipPipPipPipPipPipPip
  • Group: Advanced Members
  • Posts: 17,290
  • Joined: 2006-April-17
  • Gender:Male
  • Location:Rochester, NY

Posted 2015-August-07, 14:04

Okay, this idea is understandable and interesting. Not sure if it'll work, or if it's worth the effort, though.
--------------------
As for tv, screw it. You aren't missing anything. -- Ken Berg
I have come to realise it is futile to expect or hope a regular club game will be run in accordance with the laws. -- Jillybean
0

#7 User is offline   nullve 

  • PipPipPipPipPipPip
  • Group: Advanced Members
  • Posts: 1,945
  • Joined: 2014-April-08
  • Gender:Male
  • Location:Norway
  • Interests:partscores

Posted 2015-August-09, 15:49

First, a couple of handy definitions: Recall that Reverse Flannery by Responder (RFR) is a response to 1m showing hands with 5(+)S4+H in some range below GF strength. So let 'Flannery by Responder' (FR) similarily be a response to 1m showing 4S5(+)H hands in some range below GF strength. Then we can also say that a hand is of 'Flannery by Responder-type' (FR-type) if it's consistent with a FR response.

Whether FR-type hands pose a problem in a T*-Walsh structure s* may largely depend on the T-Walsh structure s. But this post will be about the kind of problems that may arise from using an artificial 1S rebid over 1C-1H in the desired structure s* when we start with a mundane-looking T-Walsh structure s, e.g. one where

1C = nat. or 12-14/18-19 bal.

1C-1M-1; ?:
1M = 3 M
2C+ = XYZ
1S(M=H) = 4+S2-H4+C, NF1N = 12-14 bal., 2 M (and 3- S if M=H)
2C+ = XY-NT
,
In s*, the 1S rebid over 1C-1H(=4+ H) will now probably just show 3c H support, as in

1C-1OM-1; ?:
1OM = 3 M
2C+ = XYZ
1S(M=H) = 2-S4+H4+C, F11N = 12-14 bal., 2 M
2C+ = XY-NT
,
so the danger is that 4-4 S fits may be lost in s* unless we pay attention.

For example, if Opener's has to rebid 2C in s* on

AQ9x-x-Kxx-KTxxx [corrected 11 August, was 'AQxx-x-xxx-KTxxx']

because 1S would have shown 3-card H support and 1N 12-14 bal. with a doubleton heart, a 4-4 S fit could easily be missed in favour of a silly 5-1 C fit opposite something like

Txxx-Kxxxx-A9x-x.

The situation is not as bad as it looks, partly because the analogous problem in s with

x-AQ9x-Kxx-KTxxx

opposite

Kxxxx-Txxx-A9x-x

could easily be solved in s* after (say)

1C-1D(=4+ S); 1S(=4+ H).

But we can also imagine a problem after 1C-1H(=4+ H) in s* that doesn't similarly correspond to a problem in s after 1C-1H(=4+ S). For example, the problem of locating a 4-4 spade fit with

AQ9x-xx-Kxx-KTxx

opposite

Txxx-Kxxxx-A9x-x

after 1C-1H(4+ H); 1N in s* doesn't have a counterpart in s, because with

xx-AQ9x-Kxx-KTxx

opposite

Kxxxx-Txxx-A9x-x

the bidding would simply go

1C-1H (nat. or 12-14/18-19 bal.; 4+ S)
1N-2H (12-14 bal., 2 S; 5+S4+H, weak)
P.

So the problems in s and s* don't always cancel out by symmetry. Knowing this, we might decide to use FR on weak FR-type hands, which will solve both problems in s* above, but unfortunately at the cost of a potentially useful two-level response to 1C. (I have to admit that this is the only simple solution I could think of at the time I wrote the OP, and it might show.)

Another solution involves what I for convenience shall call 'Delayed Flannery by Responder' (DFR), denoting any rebid by Responder showing a FR-type hand. But interestingly, solving the latter problem in s* involves little more than a simple trick using XY-NT, provided Opener is not allowed to bid anything else than 2H or 2S over Responder's GF relay:

1C-1H; 1N-?:
2C/2H+: as in standard XYZ
2D = weak DFR (the trick, made explicit for the sake of full disclosure) / ART GF
2H = 3-S2H (can be viewed as preference opposite weak DFR)
2S = 4S2H (can be viewed as preference opposite weak DFR)

So, using the trick with

AQ9x-xx-Kxx-KTxx

opposite

Txxx-Kxxxx-A9x-x,

the bidding would go

1C-1H (nat. or 12-14/18-19 bal.; 4+ H)
1N-2D (12-14 bal., 2 H; weak DFR / ART GF)
2S-P (4S2H; weak FR-type hand).

As for the former problem, I don't see a good reason for solving it unless we'd also be interested in solving the analogous problem in s. But maybe:

In s*:

1C-1H(=4+ H); 2C-?:
2D = weak DFR / ART GF
2H = 3-S2H (pref. opposite DFR)
2S = 4 S or 3S1-H (pref. opposite DFR)
2N = 4D6+C
3C = 3-D7+C
2S = inv DFR

Similarly, in s (where 'DRFR' = 'Delayed Reverse Flannery by Responder'):

1C-1H(=4+ S); 2C-?:
2D = weak DRFR / ART GF
2H = 4H or 1-S3H (pref. opposite DRFR)
2S = 2S3-H (pref. opposite DRFR)
2N = 4D6+C
3C = 3-D7+C
2H = inv DRFR

[I have used small letters 's' and 's*' to name structures in this post, to avoid confusion with the 'S' denoting spades.]
0

#8 User is offline   nullve 

  • PipPipPipPipPipPip
  • Group: Advanced Members
  • Posts: 1,945
  • Joined: 2014-April-08
  • Gender:Male
  • Location:Norway
  • Interests:partscores

Posted 2015-August-24, 05:24

Confession: I seem to have missed Adam Meyerson's (awm's) comment in

http://bridgewinners...nses-to-1c-gcc/

where he clearly outlines a T*-Walsh structure (the first ever?) where Responder has to bid 1D(=4+ S) first with both majors and hence also on FR-type hands. I actually do the same in a version of T-Walsh, but over 1C-1D; 2C I then play DRFR to help find 5-3 spade fits. In the corresponding T*-Walsh structure I'd play DFR over 1C-1D; 2C to help find 5-3 heart fits.
0

Page 1 of 1
  • You cannot start a new topic
  • You cannot reply to this topic

1 User(s) are reading this topic
0 members, 1 guests, 0 anonymous users