[straube]

You are South and second seat. Imps. Favorable.

---

[akhare]

1♣ - 1♦ (16+; 0-7)
1♥ - 2♣ (4+, F1; 5-7, denies 3♥, 4♠)
2♠ - 2N (Natural reverse; waiting)
3♠ - 4♥ (6♥-5♠) -> corrected

[antonylee]

Polish:
1C-1D[various]
1H[WNT better major / 15-17 4H5C / 18-20 4H5D or 5+H]-2D[nat, 4.5-8]
2S-3C
3S-4H

[rbforster]

Silent Club:

1♣-2♥ strong; GF 5/5 minors
2♠-2N ask; ♠ shortness
3♣-3♦ ask; 1255
3♥-3♠ QP ask; min (6 or fewer)
4♦-4♥ end relay; forced
P

There are just 3 important cards (A♦, K♥♠) for the grand, but with a void it will be very hard to infer exactly what responder has. Opener could ask RKC and follow up with various asking bids, but since the fit isn't in responder's primary suits it would force to the 5 level just to ask and even then it wouldn't distinguish the A♣ from other key cards til even higher. Opposite a minimum, I just gave up.

My options for keycard in hearts would have been 4♥ RKC after full shape, or 4N after he showed a minimum.

[Free]

1♣-2♦ (16+ ; GF 5+♦ unbal)
2NT-3♣ (5+♥ ; 4+♣)
3♥-4♥ (6+♥ ; fit)
pass

[PrecisionL]

C3: Copious Canape Club

1♣ (16+) - 2♣ (G.F. with 1 or both minors, no 4-cd Major) -
2♥ (SAB-3) - 2NT (exactly 2♥s) -
3♥ (Beta for controls) - 3♠ (1-2 Controls) -
4♥ (Too much missing) all pass

[straube]

IMPrecision variant

1C-2C 16+, 5-10 unbalanced w/ 5 clubs and no major
2D-3C asking*, 5D with higher short
3D-3H asking, 1255
3S-4C asking, 4 QPs
4H

*Dangerous auction because 2C could be a minimum misfitting hand. With a 6M/5M we just have to hope that partner has a fit or a max. Our only alternatives are 2H nf and 3D as 5M/5M.
It's almost pointless to ask QPs because even with 6 we won't know if partner holds the right cards. Difficult auction.

[whereagles]

Two-way pass:

pass (1♦) pass (pass)
3♦ 3NT
pass

pass = 0-8 or 15+
3♦ = majors, big hand
final pass = wise call

[benlessard]

2NT--3C (preempt in 1 min or both M 3or4 losers)
3H--4H

[yunling]

1♥（standard)-1♠(various,F1,nothing about spades)
1NT(4+♦ or 15+)-2♦(nat weak)
3♠(6+♥-5+♠ GF)-4♥