Bondy and Chvatal proved that a graph is Hamiltonian if and only if its closure is Hamiltonian, where the closure of a graph is obtained by adding an edge between every pair of non-adjacent vertices whose degrees sum to at least n.
Bondy and Chvatal proved that a graph is Hamiltonian if and only if its closure is Hamiltonian, where the closure of a graph is obtained by adding an edge between every pair of non-adjacent vertices whose degrees sum to at least n.