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I have a fairly comprehensive Full Disclosure file describing the responses here: krooh5.bss. Will not post it here, it's 28 kilos. But thanks to the symmetry, I only wrote one third of that by hand, the rest was copy-paste (might've been able to save more work with a little thought).
I hope I haven't missed some hand types totally. I added the 1NT module at the last minute, so it might have minor and even major errors (could have some no trump errors as well
).Questions, comments, suggestions welcome.
Here are the responses to 1♣. From these, it's quite easy to guess the rest:
1♣ = 15+
- 1♦ = 10+
- 1♥ = 0-6
- 1♠ = 7-9, 5+ card minor (may have 5cM if 5M6m)
- 1NT = 7-9, bal/3-suiter
- 2♣ = 7-9, 5+♥, unbal, no 4♠
- 2♦ = 7-9, 54+ ♥♠
- 2♥ = 7-9, 5+♠, 4+♣
- 2♠ = 7-9, 6+♠, 1-suiter
- 2NT = 7-9, 5+♠, 5+♦
- 3♣ = 7-9, 5+♠, 4♦, short ♥
- 3♦ = 7-9, 5-2-4-2
- 3♥ = 7-9, 5-3-4-1
- 3♠ = 7-9, 6-2-4-1
- 3NT = 7-9, 6-3-4-0
Idea, principles, weaknesses:
My main idea was to show any 5 card major at the 1st opportunity (which I agree is a bit contradictonal in a system with 4cM openers). So with 5+ hearts, the response is 2C. Hands with 5+S bid 2H or higher. Of course the step in-between, 2D, is the relay, and all heart hands make similar bids to initial 2H+ responses after 2C-2D. The direct 2D response shows both majors 54+ either way (but not 5440's)
Without a 5cM (unless it's 5332), the responder bids either 1S or 1NT. The latter is for balanced hands as well as 3-suiters; the former for 5+ card minor hands. After 1S, 1NT relays and responder's replies look quite familiar: with 5+D the rebid is 2H or higher, with 5+C one goes through 2C. And 2D shows a minor 2-suiter.
Due to the fact that 2-suited hands of the same rank are separated from other hands (and go through 2D), the responder with a 5+ card suit always holds either a 1-suiter or a 2-suiter with 4+ cards of the opposite rank. Now we can add further symmertry to the system: A 2H resonse (at some point) reveals a 2-suiter with 4+ cards in the lower suit, while direct bids at 2NT or higher show the higher suit. The middle step, 2S, shows a 1-suiter.
All this is quite nice in itself, but there's more! The full reponse scheme to 1C is: 1D GF relay, 1H negative (0-6) and 1S and up semipositives (7-9). After 1C - 1D, the opener can either relay with 1H to ask the responder discribe his shape, or bid 1S or higher himself and start to descripe himself. Either way, the bids from 1S up are the same as the direct bids, only with different strength. So this explains why I saved 2/3 of the work.
There are some weaknesses: One is the resolution of 1-suiters. As all these go through 2S, at which point all that is known is 6+ cards in one suit and no 4+ card sidesuit, there is not enough room to descibe all hands at the 3-level.
Other problem is responding with a semipositive spade-diamond 2-suiter. These must bid directly at the 3-level which might be too high. Maybe some exceptions could be made for these hands, but that would lose some symmetry.
Third thing I'm not fond of is the responder with a balanced 7-9 count stealing all no trump contracts by bidding 1NT at the first opportunity. The response scheme might be tweaked (e.g. 1S = bal/3-suiter/5+C and 1NT = 5+D or both ms), but this would again lose some symmetry.