Every simply connected, closed 3-manifold is homeomorphic to the 3-sphere. Stated above is what mathematical problem named for a Frenchman that defied experts for a century before it was solved by Grigori Perelman in 2006?
The Poincaré Conjecture Ricci flow with surgery Poincaritis Poincare's Conjecture Hamilton-Perelman Solution of the Poincaré Conjecture Solution of the Poincaré conjecture Poincaré's problem The Poincare Conjecture Poincare Conjecture Hamilton-Perelman Solution of the Poincare Conjecture Perelman's theorem Poincare theorem Poincaré Conjecture Poincaré's Problem Poincaré theorem Poincare conjecture Solution of the Poincare conjecture Poincaré conjecture Poincare's theorem Poincaré's Theorem Poincaré's Conjecture Poincaré’s conjecture Poincarré conjecture Smale's second problem Poincarre conjecture Hamilton–Perelman solution of the Poincaré conjecture Poincare's Theorem Poincaré's theorem Poincare's conjecture Hamilton-Perelman solution of the Poincaré conjecture