Questions, not proof records
Each statement record keeps the mathematical question, a dated status source, accessible references, and any pinned Lean formulation separate from proof verification.
sorry marks an admitted statement, not a proof. Source indexing does not mean the formulation has been independently built or certified by Therefore.On a smooth projective complex variety, every rational Hodge class of type is a rational linear combination of classes of algebraic cycles.
Every Jordan curve contains four points that are the vertices of a nondegenerate square.