[awm]

What do you think is "standard" if you agree to play Kaplan Inversion? How do you prefer to play it? How many spades does 1♥-1NT show?

[Jlall]

1H-1N 5+ spades
1H-1S-1N 4 spades

[gordontd]

I think Justin's description is not the Kaplan version, but is the Granville spade as played in Cambridge Precision.

[ONEferBRID]

What is Kaplan Inversion?
I've heard it is "Brown Sticker" here in USA but I'm sure it is OK across the pond.

1H - 1NT! = 5+♠, forcing 1 Rnd

1H - 1S! = may have 4♠, forcing 1 Rnd

There also is something called Kaplan Interchange.

Each have a long list of followups. KenRexford probably could remember them all.

[Gerben42]

Same as Justin.

It gets more interesting, be sure to agree

1♥ p 1♠ X ?

I think it's a good convention, but doesn't seem as useful as a passed hand.

[gordontd]

I think in Kaplan's version the 1NT response only promised four good spades - 1♠ usually showed fewer than four, but could occasionally be four poor. The significance is that the 1NT rebid was natural (but might have four spades), whereas in the Granville version the 1NT rebid promised four spades.

[Free]

I've always been convinced that Kaplan inversion is the following:
1♥-1♠ = 0-4♠, forcing
1♥-1NT = 5+♠, forcing

1♥-1♠-1NT = 4♠

Therefore 1♥-1♠-2m is always 3+ cards (otherwise you have a problem with 4=5=2=2)

[woefuwabit]

I like playing the first version of the Kaplan Inversion with a weak NT opening that can have a 5 card major. This way 1♥ - 1♠ - 2m and 1♠ - 1NT - 2m is always 4+ cards

[JanM]

ONEferBRID, on Sep 27 2009, 06:00 AM, said:

What is Kaplan Inversion?
I've heard  it is "Brown Sticker" here in USA but I'm sure it is OK across the pond.

Nothing is "Brown Sticker" in the US - that's a WBF thing.
Kaplan Inversion (whether 1♥-1NT shows 4 or 5 spades) isn't allowed under the ACBL General Convention Chart, but is allowed under the MidChart ("All other constructive rebids and responses are permitted" with an exception that doesn't apply here).

[lowerline]

Lots of possibilities here... First you have to decide whether the 1♠ response denies 4 or not and whether the 1NT response shows 5 or 4 (any 4 or only a good 4).
Having 1NT show 5 simplifies things after 1♥-1NT, but complicates things after 1♥-1♠. For instance, as the 1♠ response is limited in strenght (usually up to 11-12), you have to bid balanced GF hands with 4 spades another way. If you would use 2♣ for that, it is unlikely you will be able to bid naturally after 1♥-2♣.

A compromise between efficiency and naturalness would be to play:
1♥-1NT shows a good 4 that can be raised to 2♠ on any 3, then
1♥-1NT-2♣ shows 3
1♥-1NT-2♦ shows 4
1♥-1♠-1NT shows 4 spades
1♥-1♠-2m is just like after 1♥-1NT if you don't play the inversion.

The transfer rebids after 1♥-1♠ are superior, but with added complexity...

Steven

[Poky]

The best way is to play:
1H-1S
1NT: 4S or 3S5H(32), 11-15

This way you find a lot of excellent 2S Moysians.

1H-1S
1NT-2C=relay
2D= 35(32)
2H= 6H4S
2S= 5H4S
2NT= 45(40) weak
3C= 4504, 14-15
3D= 4540, 14-15
3H= 6H4S, good 14-15

The only problem is with the 2533 hand - you should rebid 2m with it, probably 2D if you are playing Gazzilli.

[keylime]

Larry and I use 1S as 0-3♠ or GF in spades and 1H-1NT as 4+♠, but we also play four card majors.

[fromageGB]

I wouldn't profess to know what the "standard" continuations are, but my partnerships play
1♥ 1♠ = 0-4
1♥ 1NT = 5+ spades
Strength of responder up to about a 15 count (using 1♥ 2♣ for stronger hands)

Replies to 1♥ 1♠ :
1NT = 12-16 balanced or with 4 spades.
. . 2♣ (with 8+ points) asks :
. . . . 2♦ = 12-14 balanced
. . . . 2♥ = 12-14 with spades
. . . . 2♠ = 15/16 with spades
. . . . 2NT = 15/16 balanced
. . other responder bids takeout / normal
2♣ = Gazzilli-like any hand 17+, or natural clubs any strength
. . 2♦ (with 8+ points) asks:
. . . . 2♥ = 12-14 with clubs
. . . . 2♠ = 15/16 with clubs
. . . . 2NT+ = 17+ natural
2♦ = 4+, 12-16
2♥ = 6, 11-16

[benlessard]

I like to play that
1H----1S
1NT is 12-14 and could be 4S or any bal hand and is NF.

But what i like even more is transfer by opener.

1Nt= 4C
2C=4D
2D= 6H
2H=5H+4S not reverse.

[awm]

It's amusing to get such a split decision on a question like this one.

In any case, I always thought Kaplan Inversion was like Justin said (1♥-1NT 5+♠, opener's 1NT rebid after 1♥-1♠ shows four spades) but I've played a bunch recently in a team game with a number of the Los Angeles area's better players and they all seem to play Kaplan Inversion the other way, to the degree that they sit down with new partnerships and ask "do you want to play Kaplan Inversion? okay" without further discussion. BTW some partnerships from this group play both Kaplan Inversion and Flannery (which is weird to me because I always thought one of the advantages of KI was being able to avoid rebidding 2-card minors without having to play Flannery).