Posted 2009-March-08, 13:18
I really disagree with this "systems on" idea after (1NT)-X.
The issue is that most people's notrump systems are optimized for inviting, forcing game, looking for 4-4 major fits, and making effective slam tries. This is all quite sensible when our side opens a strong notrump. On the other hand, most people's notrump systems are not particularly good at reaching two-of-a-minor when our side's hands are weak, creating a scramble when our side would be in trouble playing in notrump, or showing weak two-suiters which might offer game prospects opposite a nice fitting hand but otherwise want to subside as low as possible.
When you are defending a weak or mini notrump and the auction goes (1NT)-X-(Pass), by far the majority of advancer's invite-plus hands should simply pass. It is much better to defend 1NTX than to play our side's partial, and we will often do better defending 1NTX than we will bidding our own game. So an awful lot of the hands which would respond to partner's strong 1NT opening with stayman or various invitations are just passing now. On the other hand, occasionally advancer has utter garbage and wants to scramble. Playing 1NT and going down a few when responder has garbage is no big deal, and if opponents double we get an extra call (redouble) to help us sort things out. But defending 1NTX and letting it make with a few overtricks because advancer has garbage is quite awful.
There is also the point that you really want to double 1NT with some strong shapely hands (i.e. power doubles) because this helps limit your direct actions and takes some pressure off partner. Most people's notrump systems don't really say what to do when you open 1NT (15-17) and partner transfers to hearts, and you have a 4153 19-count (for example).
After (1NT)-X for penalty, I like to play the following:
(1) If opponents bid something which is natural (or shows the bid suit and another) then double is takeout and pass is not forcing.
(2) If opponents bid something which is artificial (like a transfer or stayman) then double shows general values and creates a force.
(3) If opponents bid something, then bidding directly over it at the two-level shows mild values (like 4-7) but not a serious invite opposite a minimum double.
(4) If opponents bid something, then 2NT lebensohl is on.
(5) If opponents pass, then bidding any of 2♦, 2♥, 2♠ are natural and show a five-plus card suit. This is normally quite weak (like 0-4), indicating a hand that does not have sufficient values to be confident defending 1NTX, but has a reasonable suit to play in. If the opponents pass is forcing (i.e. pass forces redouble) then 2♣ has the same meaning.
(6) If opponents pass is not forcing, then 2♣ just shows a lousy hand and starts a scramble at the two-level.
(7) Bidding 2NT shows a strong two-suiter, and three-level bids are invitational one-suiters. None of these ever really come up, but the idea is that with freak shape you may not really want to defend 1NTX even though you might make 3NT on your own.
Adam W. Meyerson
a.k.a. Appeal Without Merit