"Achoo!"
Lu Zhou was in his Zhongshan International mansion, sitting at his study room desk. He had a pen in his hand.
"Do I have a cold…"
He sniffed and looked at the draft paper in front of him. He gently tapped his pen on the table.
"This is kind of hard."
[… When n is greater than 2, the two n-dimensional complex dimensions intersect X ^ n (d), X ^ n (d '), there exists a differential homeomorphism if and only if their Euler number, total degree, and Pontrjagin class are equal.]
Strictly speaking, this was neither a complex analysis problem nor a partial differential equation problem. It was a unique classification of smooth manifolds.
In fact, this was a fairly popular research direction in differential topology. It was mainly about studying the invariant properties of differential manifolds under homoeomorphic mapping.