FAQ on Queueing
Last updated: June, 2006.
Q: What is a queue and what is queueing thory? A: According to The
American College Dictionary, a queue (as a noun) is (1) a braid of hair worn
hanging down behind, (2) a file or line of persons, etc.
As a verb, "to
queue" means to form a line while waiting for something.
The etymology is
from the Latin coda, meaning tail.
QUEUEING THEORY is the mathematical study
of waiting lines.
For a further discussion of queueing theory, go to "Definitions of Queueing Theory".
Q: What is the proper spelling -- "queueing" or "queuing?" A: They are
both correct spellings. The vast majority of queueing theory researchers use
"queueing." On the other hand, most American dictionaries and spell checkers
prefer the spelling "queuing." The list of well known researchers who use
"queueing" includes P. Brill, J.W. Cohen, R. Cooper, D.R. Cox, D. Gross, F.
Haight, C. Harris, B. Hnedenko, L. Kleinrock, M. Neuts, E. Parzen, N. Prabhu, S.
Ross, T. Saaty, L. Takacs, R. Wolff.
In addition, INFORMS, NSERC (Natural
Sciences and Engineering Research Council of Canada), CORS (Canadian Operations
Research Society), and the journal Queueing Systems: Theory and Applications,
all use "queueing" in their publications.
For an interesting set of letters
and comments on the two spellings, see OR/MS Today (October, 1992, p. 10 and
December, 1992, p. 10).
One of the special features of the spelling QUEUEING
is that it has five consecutive vowels (the other words with lots of vowels are
obscure: like miaoued, iouea, euouae (6), uoiauai (7). See
for additional information.
Q: What are some of the applications of queueing theory?A: Queueing
theory is useful in telecommunications, traffic control, determining the
sequence of computer operations, predicting computer performance, health
services (eg. control of hospital bed assignments), airport traffic, airline
ticket sales, the mining industry, layout of manufacturing systems. It is even
useful in determining when to remove a goalie in a hockey game.
When did mathematical queueing theory start?Agner Krarup Erlang (ref.
An Introduction to Queueing Theory, by Kashyap and Chaudhry, 1988, p. 1)
published his first paper on the subject in 1909 (according to Cooper,
Introduction to Queueing Theory (Second Edition), 1981). Erlang was an Danish
engineer who worked for the Copenhagen Telephone Exchange. Although Erlang was
preceded slightly by work of Johannsen (1907), Erlang is still considered the
father of mathematical queueing theory. A good summary of the history of
queueing theory up to 1961 can be found in Saaty's Elements of Queueing Theory,
1961, pp. 20-25. Also see Syski's article in the book Frontiers in Queueing
Return to THE QUEUEING THEORY PAGE.