Step 2: The extensible cells are constructed by combining all the cells with at least one dot character and the same start and end solid characters. The location list is updated to reflect the start and end position of each occurrence. Continuing the previous example, b-d is generated at this step with b-d = {(2, 4), (6, 9)}. All cells m with |m| <K are discarded. In the example, the only surviving cells are ab, b-d with ab = {(1, 2), (5, 6)} and b-d = {(2, 4), (6, 9)}