“…Because the major obstacle of speeding up each iteration lies in the size of data, it is natural to compress the data such that it fits into the main memory, as by [6,7,8]. However, as pointed out by [6], even the best compression scheme requires about .6 bytes per hyperlink, which still results in an exceedingly large space requirement. Others are to design I/O-efficient algorithms, such as [9,10], which can handle any size of data without any particular memory requirement.…”