Today’s the Putnam, for which I’d been coaching a few people at Budapest Semesters in Mathematics, the only place outside North America where the Putnam can be administered. The “afternoon session” ends at midnight, to match American time, so I haven’t seen the problems yet. I’ll make the bold prediction (probability .8 or so) that at least one of the problems is one of:

A functional equation to be solved by making the arguments of two terms equal,

A matrix whose determinant is 0 because it has small rank,

A pair of reals whose replacement by one complex trivializes the problem, or

The lifting lemma.

(This isn’t even starting on more general things like that integral calculations and blind algebra are so frequent on it.)