Strong Jump Shift

[Bbradley62]

I open 1♣ and partner replies 2♦. The Express Full-Disclosure card says this shows 4+♦ and 17+points. When/why would you do this with only 4 diamonds?

[jillybean]

I wouldn't, your partner was either a bot or an expert?

[Bbradley62]

Jilly: I'm questioning the script presented by the full-disclosure convention card, not the action of my partner (who actually had a real diamond suit, as I would expect him to have).

[mycroft]

Soloway jump shifts (don't know if this is what this CC is playing) are in three cases:

 

- single suited (diamonds), strong, basically willing to play opposite a singleton

- two suited, yours and partner's (C+D, here)

- hand too strong for immediate NT

but not "two-suiter not including opener's suit".

 

In cases 2 and 3, I can see a 4-card suit being bid; if you don't raise, partner will pattern out (NT with big balanced, anything else control bid with opener's suit).

[Bbradley62]

So, 3343 and (23)44 hands with 17+ bid strong 2♦ instead of forcing 1♦? What is the advantage?

[palabreur]

So, 3343 and (23)44 hands with 17+ bid strong 2♦ instead of forcing 1♦? What is the advantage?

 

Not quite. Those hands are balanced, so they use a jump shift only if they are 18-19 hcp. 1C-2D shows either 18-19 bal, a strong hand with diamonds, or a strong hand with diamonds and clubs.

 

Why do we do this? So we can immediately start thinking about slam, without needing to jump later on. 1C-2D, now you know to evaluate your hand for slam. 18-19 balanced is relatively rare, so probably evaluate your hand based on a club or diamond slam.