Discuss situations under which

Consider the sequence in a system that holds four pages in memory: 1 2 3 4 4 4 51. The most frequently used page replacement algorithm evicts page 4 while fetching page 5, while the LRU algorithm evicts page 1. This is unlikely to happen much in practice. For the sequence "1 2 3 4 4 4 5 1," the LRU algorithm makes the right decision.