Along these lines, here is the system I am working on -
1♣ = 16+ or rule of 25 (EBU regulations )
1♦ = 10-15, any hand with precisely 4 spades
1♥ = 10-15 unbalanced (4♥5+minor or 6+♥) or 10-12 balanced
1♠ = 10-15, 5+♠
1NT = 12-15, denies 4♠. 13-15 if 4♥.
2♣ = 11-15, unbal, no 4cM (so either 6♣ or 5♣4♦)
2♦ = as 2♣
2♥ = 11-15, 5♥4+minor
2♠ = weak
2NT = 10-15, at least 5-5 minors, offensive
I think I am correct in saying that Blue Club opens 1♠ with 4-5 and 5-4 in the majors. This seems sensible, to allow both suits to be shown, but means that the 1♠ opening is much more frequent than 1♥, which feels wrong. It also leads to some ambiguity over which suit is the longer. This structure solves this - you always show spades at the first opportunity, but there is no later ambiguity. Intuitively the 1♦ opening here feels like it shouldn't be frequent enough, but I think it is the most frequent of the limited openings (24% of hands have precisely 4 spades). Also, the extra room is needed both to look for 4-4 heart fits and to sort out the wide balanced range. My idea for responses:
1♥ = enquiry, either weak or a full invite. Now 1♠ = would have raised a natural 1♥ response (either 4♥ bal or 3♥ unbal), others natural. Opener only starts jumping around with an exceptional hand.
1♠ = enquiry, either mildly invitational or GF. Now 2♠ and above are used for showing run-of-the-mill maxima.
1N->2♥ = transfers (2♥=inv+ with ♠)
The 1♥ opening can occasionally be 5 cards - 10-12 5♥332 will be treated as a 4 card suit, while max 5-5s and decent 5-6 shapes can open 1♥ intending to jump-shift over a 1NT response or bid on if raised. I need to think more about continuations here, but a couple of structures seem reasonable -
1♠ = 5+♠
1N = nat NF
2m = GF (possibly 2♣ as some kind of relay)
1♠ = general enquiry, any strength
1NT = 5+♠ NF - or it could be F1 if opener is to raise on 2533 and 24(34)
2m = nat NF
I like removing the hands with 4 spades from the weak NT, these are the ones that rate to lose out when you bury your fit, whereas when you bury your heart fit you may bury the opponents spade fit at the same time. It will help responder judge some competitive auctions, and eliminates the need for garbage stayman - 1N:2♣, 2♦:2M is now obviously invitational with a 5 card suit.
[This paragraph added later] With the possible exception of hands with 5+♥, this structure should have a positive expectation after making a limited opening. The biggest loss, in comparison to similar systems, is the need for 2♦ and 2♥ to show intermediate hands instead of weak hands.
In case anyone is interested in the older ramblings -
Strong Diamond
Strong Club
I'm still fond of the strong diamond idea - it would have allowed very light opening bids - but I couldn't find anywhere to put the major two-suiters comfortably. I briefly considered using 1♦ as any 14-16 and 1♣ as 17+ any or 10-13 both majors, but it seems that the 1♣ opening would be much more vulnerable than a Swedish Club, because the weak hand is of lesser frequency and having both majors decreases the chance that your opponents have game.
This post has been edited by MickyB: 2006-August-09, 13:06