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Claude Elwood Shannon
Born: 30 April 1916 in Gaylord, Michigan, USA
Died: 24 Feb 2001 in Medford, Massachusetts, USA
Claude E Shannon's father was also named Claude Elwood Shannon and his mother was Mabel
Catherine Wolf. Shannon was a graduate of the University of Michigan, being awarded a degree in
mathematics and electrical engineering in 1936. Although he had not been outstanding in mathematics,
he then went to the Massachusetts Institute of Technology where he obtained a Master's Degree in
electrical engineering and his Ph.D. in mathematics in 1940. Shannon wrote a Master's thesis A
Symbolic Analysis of Relay and Switching Circuits on the use of Boole's algebra to analyse and optimise
relay switching circuits. His doctoral thesis was on population genetics.
At the Massachusetts Institute of Technology he also worked on the differential analyser, an early type
of mechanical computer developed by Vannevar Bush for obtaining numerical solutions to ordinary
differential equations. Shannon published Mathematical theory of the differential analyzer in 1941. In
the introduction to the paper he writes:The most important results [mostly given in the form of theorems with proofs] deal with
conditions under which functions of one or more variables can be generated, and
conditions under which ordinary differential equations can be solved. Some attention is
given to approximation of functions (which cannot be generated exactly), approximation of
gear ratios and automatic speed control.
Shannon joined AT&T Bell Telephones in New Jersey in 1941 as a research mathematician and
remained at the Bell Laboratories until 1972. Johnson writes in [4] that Shannon:... became known for keeping to himself by day and riding his unicycle down the halls at
night.
D Slepian, a colleague at the Bell Laboratories wrote:Many of us brought our lunches to work and played mathematical blackboard games but
Claude rarely came. He worked with his door closed, mostly. But if you went in, he would
be very patient and help you along. He could grasp a problem in zero time. He really was
quite a genius. He's the only person I know whom I'd apply that word to.
Working with John Riordan, Shannon published a paper in 1942 on the number of two-terminal seriesparallel networks. This paper extended results obtained by MacMahon who had published his early
contribution in the Electrician in 1892.
Shannon published A Mathematical Theory of Communication in the Bell System Technical Journal
(1948). This paper founded the subject of information theory and he proposed a linear schematic model
of a communications system. This was a new idea. Communication was then thought of as requiring
electromagnetic waves to be sent down a wire. The idea that one could transmit pictures, words, sounds
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etc. by sending a stream of 1s and 0s down a wire, something which today seems so obvious as we take
this information from a server in St Andrews, Scotland, and view it anywhere in the world, was
fundamentally new.
Shannon considered a source of information which generates words composed of a finite number of
symbols. These are transmitted through a channel, with each symbol spending a finite time in the
channel. The problem involved statistics with the assumption that if xn is the nth symbol produced by
the source the xn process is a stationary stochastic process. He gave a method of analysing a sequence of
error terms in a signal to find their inherent variety, matching them to the designed variety of the control
system. In A Mathematical Theory of Communication , which introduced the word "bit" for the first
time, Shannon showed that adding extra bits to a signal allowed transmission errors to be corrected.
Slepian, in the introduction to [2], writes:Probably no single work in this century has more profoundly altered man's understanding
of communication than C E Shannon's article, "A mathematical theory of communication",
first published in 1948. The ideas in Shannon's paper were soon picked up by
communication engineers and mathematicians around the world. They were elaborated
upon, extended, and complemented with new related ideas. The subject thrived and grew to
become a well-rounded and exciting chapter in the annals of science.
On 27 March 1949 Shannon married Mary Elizabeth Moore. They had three sons and one daughter;
Robert, James, Andrew Moore, and Margarita. He continued his work showing how Boolean algebra
could be used to synthesise and simplify relay switching circuits. He also proved results on colouring the
edges of a graph so that no two edges of the same colour meet at a vertex. Another important paper,
published in 1949, was Communication theory of secrecy systems.
In 1952 Shannon devised an experiment illustrating the capabilities of telephone relays. He had held a
position as a visiting professor of communication sciences and mathematics at the Massachusetts
Institute of Technology in 1956, then from 1957 he was appointed to the Faculty there, but remained a
consultant with Bell Telephones. In 1958 he became Donner Professor of Science [1]:When he returned to MIT in 1958, he continued to threaten corridor-walkers on his
unicycle, sometimes augmenting the hazard by juggling. No one was ever sure whether
these activities were part of some new breakthrough or whether he just found them
amusing. He worked, for example, on a motorised pogo-stick, which he claimed would
mean he could abandon the unicycle so feared by his colleagues ...
R G Gallager, a colleague who worked at the Massachusetts Institute of Technology, wrote:Shannon was the person who saw that the binary digit was the fundamental element in all of
communication. That was really his discovery, and from it the whole communications
revolution has sprung.
His later work looked at ideas in artificial intelligence. He devised chess playing programs and an
electronic mouse which could solve maze problems. The chess playing program appeared in the paper
Programming a computer for playing chess published in 1950. This proposal led to the first game
played by the Los Alamos MANIAC computer in 1956. This was the year that Shannon published a
paper showing that a universal Turing machine may be constructed with only two states.
Latterly he felt that the communications revolution, which he had played a major role in starting, was
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going too far. He wrote:Information theory has perhaps ballooned to an importance beyond its actual
accomplishments.
Marvin Minsky described Shannon as follows:Whatever came up, he engaged it with joy, and he attacked it with some surprising resource
which might be some new kind of technical concept or a hammer and saw with some scraps
of wood. For him, the harder a problem might seem, the better the chance to find something
new.
He also applied his inventing genius to other areas [1]:... he once invented a two-seater version of his unicycle, and it is probably true that no one
was anxious to share it with him. A later invention, the unicycle with an off-centre hub,
would bring people out into the corridors to watch him as he rode it, bobbing up and down
like a duck.
Shannon received many honours for his work. Among a long list of awards were the Alfred Nobel
American Institute of American Engineers Award in 1940, the National Medal of Science in 1966, the
Audio Engineering Society Gold Medal in 1985, and the Kyoto Prize in 1985. He was awarded the
Marconi Lifetime Achievement Award by the Guglielmo Marconi International Fellowship Foundation
in 2000. It was the first time that organization, known for its annual Fellowship Prize, gave this
particular award.
He was afflicted by Alzheimer's disease, and he spent his last few years in a Massachusetts nursing
home.
Article by: J J O'Connor and E F Robertson
October 2003
MacTutor History of Mathematics
[http://www-history.mcs.st-andrews.ac.uk/Biographies/Shannon.html]
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