Optimal Algorithm
The optimal algorithm, called Belady’s algorithm, has the lowest fault rate for any reference string.
Basic idea: replace the page that will not be used for the longest time in the future.
Basic problem: phone calls to psychics are expensive.
Basic use: gives us an idea of how well any implementable algorithm is doing relative to the best possible algorithm.
- compare the fault rate of any proposed algorithm to Optimal
- if Optimal does not do much better, then your proposed algorithm is pretty good.
- If your proposed algorithm doesn’t do much better than Random, go home.