In other words, cells originally belonging to the same region could be assigned to different regions when (a) a top row is not connected to them and (b) they are separated by a region or a shaded cell in the current row. Initially, when cells in the current row are connected with those in the preceding row—by considering the original regions—, the updated symbols representing these regions in the upper row are carried down to the lower row. (g) Generate the regions for the current row by first propagating the regions of interconnected cells from the uppermost row and, secondly, creating new regions for the remaining cells (as described above).