[DavidKok]

jillybean, on 2025-February-07, 02:30, said:

Where do you get to using your favorite methods?

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There are some subtleties on this auction. On hearing South's shape, North first needs to confirm the fit. North's hand is worth significant upgrades with the double fit and control in every suit. At the same time, South has a bunch of extras on the auction. The diamonds might be a source of tricks if North has ♦A or ♦J, and control in all suits helps. The ♥J is also nice.
Over 3♥, South makes a cheap control bid. North now skips 3NT (nonserious) in favour of 4♣ (serious). With the evaluation cited above this is a clear choice, though there's a fun double wriggle for experts, see end.
South now has to make a choice - 4♦ Last Train intending to bid on, or take charge. Note that there is no world where I'd bid Last Train and then pass 4♥ - the hand is too good, and partner's serious slam try pushes it even further past the line. In line with general principles I like South asking for key cards here, with the undisclosed source of tricks. Note that both hands have control of all suits, a rarity. Instead 4♦-then-bid-on (either 4♠ or 4NT) would say "partner, I have a bunch of extras, but I was hoping you could take charge" - typically aces and spaces. But South can see that North might need more information than just key cards for the slam, so this is a risky bet. There's also the option of bypassing keycards entirely, but on this deal I think that's not the right way to go. We have the trick-taking potential, we have the controls, all we need is the key cards.
On my auction South never learns of the double fit, though it was used by North to re-evaluate the hand to a serious slam try. I think this is a flaw in my methods, but not one I'm going to fix any time soon. Double fits on uncontested auctions aren't the greatest priority.


Double wriggle, for fun:

Spoiler

North (almost) knows South's shape. In particular, North knows that South has 0-1 clubs, and therefore a control. This raises two immediate questions: 1) should North's 4♣ show first round control, as the king is wasted opposite 0-1 cards? And 2) If North bids 3NT, what would South's 4♣ show? First round control, generic extras waiting bid, something else? I think it is sensible for North's 4♣ here to require first round control, and then North can immediately jump to 4♦ ('Serious Last Train' - take a moment to figure out what hand that could be). But I do not have this agreement in any partnership, and I think the nuances are too subtle to rely on without prior discussion. So I'm sticking with the simple serious mixed control meaning that is default in my partnerships. That's the first wriggle.

The second one is that North would really really like to show the ♦A. I even have agreements for this - showing a control in partner's known 5(+) suit is A/K, not shortage. North can guess that South would like to have this information for re-evaluating their hand. By bidding 4♣, it is practically guaranteed that there is no room to show this (even if we bypass RKC, a delayed 5♦ bid would be Last Train, again). There is a case to be made that, in the absence of an agreement that 4♣ shows a first round control on this auction, North should underbid with 3NT just to show the ♦A later. However, my Last Train gets in the way again - the auction 3NT-4♣; 4♦ would not show the ♦A. But in a different partnership I think a case could be made for bidding this way. That being said, I think this is masterminding. That's the second wriggle.

[mw64ahw]

Playing my Esoteric Unbalanced ♦ I have a slight difference in auction which has South playing the contract

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[jdiana]

jillybean, on 2025-February-07, 02:14, said:

We had agreed to play RKC1430

Yes, but with hearts as trump, there are only two keycards.