Smale's problems
collection of 18 then-unsolved mathematical problems proposed by S. Smale in 1998
Jacobian conjecture
conjecture asserting that, over a characteristic-zero field K, given a polynomial map f: Kⁿ → Kⁿ, if its Jacobian determinant J: Kⁿ → K is a nonzero constant map, then f admits a polynomial inverse g: Kⁿ → Kⁿ