[cnszsun]

Very instructive discussion, i got a lot from it.
I jumped to 6♦ at table because i don't want to bid rkc with a void and other bids could be ambigious to my pick-up partner (he is a BBO star), but now i think justin's 4nt is very practical, partner almost surely have ♠Ace for his 4♠ bid. By bidding 4nt, grand slam interest can be expressed later and also slight chance to stop at 5♦ if partner is missing two minor Aces.

[kenrexford]

My take is on this deal is very similar to Justin's, although my statement of more general slam-exploration theory would apparently be different as I am more inclined to make cooperative cuebids than seems to be expressed in his statement of theory.

On this deal, partner's 2♦ call was nothing exciting, possibly even a convenience bid initially. So, I see little point to doing anything except what Justin suggested -- staying low, flexible, and honest. After 3♣, however, the analysis changes.

What is 3♣? I doubt that it simply shows a 3154 pattern. With that pattern, one could probably bid 2NT with many ugly GF hands, planning to correct 3♥ to 3NT, if the spade stop is quality and/or the slam prospects for the minors are poor. Thus, whereas 3♣ first creates a guess of 3154 pattern, or better, I am also inclined to believe that minor suit quality is sound or better and that spades are not a great source of wastage (unless compensating values exist), something hinted at by Justin.

So, I comfortably bid 3♦. Partner now bid 3NT. I still figure partner for quality in his suits. With AJ-A alone, only 5-4, I myself would probably bid 2NT, planning to bid 3♠ as a mild slam try if Opener bids 3♣ or makes a delayed raise of diamonds (3♦). So, I anticipate something like A-AQ or AQ-A in the minors, possibly as bad as QJxxx-AQxx, for the 3NT call.

I then make a clearly right call of 4♣. How can this be wrong?

At this point, the story unfolds well. Partner cuebids 4♠. This is cooperative, perhaps. But, the big story missed is the failure of partner to cuebids trumps (by bidding 4♦). I expect, therefore, either Axxxx-AQxx in the minors, or possibly QJxxx-AQxx. He would have done that to allow me to use 4♠ (I would insist on this) as RKCB for diamonds and to tell me that his diamonds are good ones.

This failure, and the 4♠ call (apparently a cue in the techniques), convinces me that partner has something like ♠AJ10 ♥x ♦Axxxx ♣AQxx or ♠AJ10 ♥x ♦QJxxx ♣AQxx. Opposite either, 6♦ seems to be a good contract. 7♦ might make opposite the former, but it does not seem "good." As I am afraid that 4NT is a signoff in this auction, I'll blast to 6♦.

[the hog]

When I was a little tacker someone once gave me some good advice. That was "Support with support". I have followed that philosophy ever since. Hence my second bid would have been 3D. No one I ever played with or will ever play with bids 2D as a "convenience bid" by the way.