Answer - The Belady's anomaly is a situation in which the number of page faults increases when additional physical memory is added to a system. This anomaly arises in some algorithms that implement virtual memory. The virtual memory allows programs larger than the physical memory space to execute. An algorithm suffers from this problem when it cannot guarantee that a page will be kept when a small number of frames are available. An optimal algorithm would not suffer from this problem as it replaces the page not to be used for the longest time. The anomaly occurs when the page replacement algorithm will remove a page that will be needed in the immediate future. An optimal algorithm will not select such a page that will be required immediately. This anomaly is also stated to be unbounded.