Is membership in the Mandelbrot set decidable over the reals? Penrose's 1989 question — computable in weaker models, open in Blum–Shub–Smale.
The Problems
Not schoolwork — the questions that resisted Erdős, Hilbert, and everyone since. The club keeps three shelves: what is still open, what AI recently settled, and what took humanity centuries.
Tagged computability — 1 entry. Clear