Although most queues in everyday life follow the first-in-first-out protocol there are familiar situations where it is acceptable for people to “jump the queue”: for example in a hospital casualty department patients may in general be treated in order of their arrival times, but a severely injured accident victim is certain to be dealt with before someone with a fishbone in the throat no matter at what times they arrived. It is natural to say that the accident victim has higher priority than the patient with the fishbone. There are also situations in the operation of a time-sharing computer system where requests are handled not in the order in which they are made in time but according to the priorities assigned to them by the operating system.
Unable to display preview. Download preview PDF.