Tait's conjecture states that "Every polyhedron has a Hamiltonian cycle (along the edges) through all its vertices". It was proposed in 1886 by P. G. Tait[?] and disproved in 1946, when W. T. Tutte constructed a counterexample with 25 faces, 69 edges and 46 vertices.
The conjecture could have been significant, because if true, it would have implied the four color theorem.
... History of Brazil
Brazil was first sighted by Europeans in 1500 and developed as a Portuguese commercial colony, based to a large extent on slavery. The Portuguese ...