Convention-of-the-Week Club.
( From Matts Granovetter )
Puppet Stayman

♠ Jxx
♣ xxxx

Partner opens 2NT. What is your response?

Convention of the Week: = 
Puppet Stayman

After a 2NT opening, 3C asks for a 5-card major. It can also be played after a 1NT opening,

but we will concentrate on 2NT in this week's newsletter.

There are a few different sets of responses for this convention, but one of the most popular is this:

2NT - 3C
3D = one 4-card major
3H = 5 hearts
3S = 5 spades
3N = no major

Over a 3D bid, responder can:
(1) sign off in 3NT if he was looking only for a 5-card major
(2) bid the major he does NOT hold with one 4-card major
(3) bid 4C with both majors
(4) bid 4D with both majors and a slam try

Two examples:

♠ KQxxx   ♠ Jxx
KQx       xx
  KQx       AJTx
♣ AJ           ♣ xxxx

2NT     3C
3S        4S

♣ AKx      ♣ Qxx
KQxx    Jxxx
Kx          Axxx
♣ AQxx    ♣ xx

2NT     3C
3D      3S

Alternatively, opener could bid 4C over 3S as a slam try and responder transfers back to 4H

(via 4D) and then passes.

The Fly in the Ointment:

♠ Axx        ♠ Jxxxx
Kx          AQxx
AKxx      x
♣ AQxx     ♣ xxx

2NT     3C
3NT     pass

When responder holds 5-4 in the majors, he may lose the 5-3 fit. You  could play that a 3D Jacoby

transfer response followed by 3S shows 5 hearts and 4 spades, but you are still going to miss the

 5-3 spade fit when you have 5 spades and 4 hearts.

A solution is to switch the 3H and 3NT responses to 3C. Play 3H as no major and 3NT as 5 hearts:

2NT - 3C
3D = one 4-card major
3H = no major
3S = 5 spades
3N = 5 hearts

Over 3NT, responder should use 4D as a transfer to hearts.

Over 3H, responder can bid 3S with 5 spades and 4 hearts, so the partnership doesn't miss the 5-3 spade fit.

♠ KJx        ♠Qxxx
AKxxx   xxx
  AKx       xx
♣ Ax          ♣ Kxxx

2NT     3C
3NT     4D
4H        pass

Here opener shows 5 hearts and responder signs off via a transfer bid.

What do you lose by playing 
Puppet Stayman?
You lose the ease of bidding a 54 major-suit shape if playing the traditional Puppet Stayman responses.

But even playing the modified  version, you lose whenever fourth hand doubles for the killing lead.
The price for a comprehensive structure over partner's no trump  opening is that the more bids you make

 the more information you allow the opponents to exchange.

For example, look at this layout:

         ♠ Q9xx
         ♣ xxx

♠ JTxxx           ♠   x
Qx                   KJTxx
  xx                    Kxx
♣ QJxx              ♣ T9xx

         ♠ AKx
         ♣ AK

Over normal 2NT bidding, the auction goes:

South   West    North   East
2NT     pass     3C         pass
3D        pass     3NT      (all pass)

Club lead, diamond finesse loses, nine tricks. Or spade opening lead, and ten tricks.

Puppet Stayman:

South   West    North   East
2NT     pass     3C        pass
3D       pass      3H       double
3NT     (all pass)

Heart lead, diamond finesse loses, down one.

Puppet Stayman can also be used over 1NT, with the same sequences one level lower.

Check List:  Puppet Stayman

After a 2NT opening (or a 2C opening followed by a rebid  of 2NT), responder's 3C asks

for a 5-card major in the traditional Puppet Stayman method.

Our partnership will reverse the 3H and 3NT responses.

 We also play Puppet Stayman over 1NT.