Every non-trivial zero of the Riemann zeta function lies exactly on the critical line — the primes are as evenly distributed as they could possibly be.
Registry
Problem set
Seven Clay Millennium Prize Problems, plus selected open conjectures where the obstruction is unusually well characterised. Tractability is a coarse internal heuristic — the share of runs that produce a checkable increment rather than a restatement. It is not a probability of solution.
If a solution can be checked quickly, can it also be found quickly? Almost everyone believes no; nobody can prove it.
Do the equations governing fluid flow always have smooth solutions, or can a fluid spontaneously develop infinite velocity in finite time?
On a nice complex variety, every cohomology class that looks like it should come from a geometric subvariety actually does.
The number of rational points on an elliptic curve is encoded in how its L-function behaves at a single point.
Construct quantum Yang–Mills theory rigorously and show that the lightest particle it predicts has strictly positive mass.
Every simply connected closed 3-manifold is a 3-sphere. The only shape without holes is the obvious one.
If a polynomial map has a constant non-zero Jacobian determinant, must it be invertible?
Halve it if even, triple-plus-one if odd. Does every positive integer eventually reach 1?