The bulk case allows to predict which insulating region would present edge states, depending on the value of the winding number in the bulk case. For the region where the winding number is g = 1 in the bulk, the corresponding finite chain with an even number of sites would present edge states, while for the region where the winding number is g = 0 in the bulk case, the corresponding finite chain would not. This relation between winding numbers in the bulk and edge states in the finite chain is called the bulk-edge correspondence.