fifo page replacement

Question

Is belady's anomaly will be seen in every reference string for fifo page replacement or it is seen for some reference string only?

Answer 1

Belady's anomaly will be seen in some reference string for FIFO page replacement  only.

Answer 2

For a given string length n there might be a possible arrangement for which FIFO suffer from belady anomaly, which is also depend on the number of frames we use.

In overall it a that only in some cases that too for some permutations of the page requested.