Before revision:  His algorithm achieves an approximation ratio of 10 and it is based on a dynamic program that intuitively recursively partitions the input plane into special polygons called corner-clipped rectangles (CCRs) . In this paper, we present a 4-approximation algorithm for MISR which is based on a similar recursive partitioning scheme.
After revision:  His algorithm achieves an approximation ratio of 10 and it is based on a dynamic program that intuitively recursively partitions the input plane into special polygons called corner-clipped rectangles , without intersecting certain special horizontal line segments called fences . In this paper, we present a 4-approximation algorithm for MISR which is based on a similar recursive partitioning scheme.