Chamaco, on Aug 10 2005, 07:07 AM, said:
The relevant range for a wjs cannot have 7-8 hcp (even 6 hcp is suspicious, if pard has 18/19 hcp we might miss game), according to all textbooks (see for instance, among others, Hardy's books): the reason is that we are in an unlimited opening world, and we risk preempting pard.
A weak js, in natural systems DENIES ANY WILLINGNESS OF CONSTRUCTIVE AUCTIONS, unless there is fit. t shows a hand worse than a 3-level preempt.
You can indeed use up to 8 hcp, but only in a limited opening world (strong club etc), because you do not risk preempting pard.
Just because you put it in bold type and underline it, doesn't make it true.
Everybody I know in my country (England) who plays weak jump shifts (they aren't that common here) uses them as a constructive tool. In fact, your argument about pre-empting partner is exactly why we play them as roughly 4-8 HCP and constructive. You jump in a suit to show a well-defined hand. Whether your definition is 0-5 or 4-8 doesn't change that fact that you have described your hand very well to partner, who now can make an informed decision.
I'm probably just going to repeat what Gerben said, but let me explain why so many people play the WJS as constructive. Define a 2-level jump response to partner's 1-of-a-minor opening as
3-7 HCP with a 7-card suit, 4-8 with a 6-card suit, depending a little on vulnerability, suit quality and level of fit for partner's suit (e.g. Kxxxxx x QJx xxx is often a 1S response to 1D becaue you could easily want to play in diamonds; KJ109xx x xxx xxx is a 2S response at all vulnerabilities).
Now you have three superb new constructive weapons:
i) 1m - 1M - 2 either m - 2M shows an invitational hand with 6 cards (about 9-12) and allows you to play at the 2-level on a misfit, or to investigate the best game at a sensible level. Standard bidding has no good way to show this hand (you have to overbid or underbid).
ii) 1m - 1M - 2 either m - 3M is game forcing with a good suit. This replaces some of the strong jump shift hands you have lost, though it doesn't have to be quite SJS strength.
iii) Responder has defined their hand well when she makes a WJS, so opener can make an informed decision. With 18-19 balanced for example, opener just bids game. Some people play system after a WJS - you could play exactly what you play in response to a weak two such as an Ogust 2NT enquiry. We play step 1 as a shortage ask (followed by step 1 as a trump quality ask for slam purposes).
Plus you have put in a mild pre-empt.
Alternatively, you could play the WJS as 0-5. I agree that this is a more common American treatment, and the constructive version seems to be more common in England. Personally I can see no advantage in this treatment because
i) 0-5 with a 6-card suit is (I think) less common than 4-8 with a 6-card suit, so the pre-emptive impact is less common
ii) You have removed one constructive call (the SJS) from your system, but not replaced it with anything, so your constructive auctions have to cover just as many hand types as before with fewer calls.
There must be some reason to play them this way - very weak - because so many people seem to do so. So I'm not going to say in bold, and underlined, that you cannot play it your way. But I'd rather play SJS.