So it's 3-2-4-4 versus 3-1-4-5. Note that if declarer holds one of:
♠Qxx
♥xx
♦Jxxx
♣KQxx
♠Qxx
♥Q
♦Jxxx
♣Kxxxx
then I am legitimately squeezed in the round suits. So I must assume that declarer holds either:
♠Qxx
♥Qx
♦Jxxx
♣Kxxx
♠Qxx
♥x
♦Jxxx
♣KQxxx
(there are some other possibilities where declarer has no club king, but in those cases it is always right for me to pitch club, and many of those hands wouldn't have accepted the slam invite).
It's not particularly obvious how I would "know" which of these is right, but I expect:
(1) The first hand is probably more likely a priori (more balanced).
(2) The second hand might've bid 3
♣ over 2
♣, or over 2
♥, or tried clubs over 4NT.
I'm pitching clubs.
Adam W. Meyerson
a.k.a. Appeal Without Merit