Mask layout data of a lithographic mask includes polygons that each include horizontal and vertical edges. Each of a number of target edge pairs is defined by two edges of one or more of the polygons. A search box having a boundary coincident with a given edge of the edges of the polygons is specified. Whether the search box includes at least one edge of the edges of the polygons in addition to the given edge is determined. Where the search box includes at least one edge, at least one of the target edge pairs is specified as including the given edge and one of the at least one edge. For each target edge pair that has been specified, a manufacturability penalty value is determined. A dynamic manufacturability constraint table and a non-zero multiplier table are maintained.