[lotharbot]

[Background: I am Dove's husband, and remember the incident described]

What actually happened was the professor posed the question in class as an open research question, which he regularly did, with no particular expectation that any students would work on it or make meaningful progress. My wife happened to sit down in her office and come up with a counterexample, which she wrote on paper and left in the professor's physical mailbox on campus fairly late in the evening. He had almost certainly already left campus for the weekend by that time. This wasn't a case of some sort of arrogance or lack of wisdom, just a case of non-instantaneous asynchronous analog communication methods.

This particular professor was extremely good at letting others contribute. As soon as the contribution actually reached him, he assessed it and used it.