[JonnyQuest]

A friend and I were discussing Keri (we've not yet decided it's efficacy) and wondered the following.

Can it work after a 1NT rebid? For example, 1m - 1M - 1NT?

Thanks!

[Zelandakh]

Is there any advantage to playing Keri over 2-way Checkback here?

[P_Marlowe]

Structures after a 1NT opening and after a 1 NT rebid are complementary, sort of.

If you play weak NT, you need to keep options of staying low after a 1NT opening,
but can mostly ignore those, if opener made a 1 NT rebid, showing a strong NT.
Hence after the rebid, you can focus on exploring the best slam / evaluation of slam
prospects.
With strong NT it is the other way round.

In other words, using Keri makes only sense, if the rebid NT could still be a opener
NT, you just removed some shapes, or you happen to play a super mini NT and the rebid
now showes a trad. weak NT.

With kind regards
Marlowe

[mycroft]

We play Keri/Weak NT (in a strong NT world) and XYNT (and full XYZ) in your auction. Similar ideas (can get out in 2♦, can show shutdown, invitational, gf hands quickly) but since you've already shown a major, dealing with some of the Keri bulk (1♣-1♠; 1NT-2♣!; 2♦!-3♠ "do I really have to do all that and take away the whole 3 level to show 5 diamonds?" for instance) is much less effective. Also, the transfers into the known suit don't actually transfer anything (you're playing it anyway).

We do (well, did, we don't play natural any more) play Keri/NT overcall. We did it for simplicity, but the bad Keri hands (the GF Stayman/Puppet ones, frankly) are less frequent, and being able to get out in 2♦ is much more of a plus, so it worked out.

The answer to your question will also depend on what 1♥-1♠; 1NT, 1♣-1♦; 1NT, and 1m-1♥; 1NT mean, particularly whether you bypass a 4cM to show the balanced hand and whether you consider all 5♥332s balanced.