Working Set Model
Peter Denning defined the working set of a program as a way to model the dynamic locality of a program in execution.
Definition:
WS(t,w) = {pages i s.t. i was referenced in the interval (t,t-w)}
t is a time, w is the working set window, a backward looking interval,measured in references.
So, a page is in the WS only if it was referenced in the last w references.