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| title | chunk | source | category | tags | date_saved | instance |
|---|---|---|---|---|---|---|
| Claude Shannon | 6/7 | https://en.wikipedia.org/wiki/Claude_Shannon | reference | science, encyclopedia | 2026-05-05T14:43:48.523076+00:00 | kb-cron |
In 1949 Shannon completed a paper (published in March 1950) which estimates the game-tree complexity of chess, which is approximately 10120. This number is now often referred to as the "Shannon number", and is still regarded today as an accurate estimate of the game's complexity. The number is often cited as one of the barriers to solving the game of chess using an exhaustive analysis (i.e. brute force analysis).
=== Shannon's computer chess program === On March 9, 1949, Shannon presented a paper called "Programming a Computer for playing Chess". The paper was presented at the National Institute for Radio Engineers Convention in New York. He described how to program a computer to play chess based on position scoring and move selection. He proposed basic strategies for restricting the number of possibilities to be considered in a game of chess. In March 1950 it was published in Philosophical Magazine, and is considered one of the first articles published on the topic of programming a computer for playing chess, and using a computer to solve the game. In 1950, Shannon wrote an article titled "A Chess-Playing Machine", which was published in Scientific American. Both papers have had immense influence and laid the foundations for future chess programs. His process for having the computer decide on which move to make was a minimax procedure, based on an evaluation function of a given chess position. Shannon gave a rough example of an evaluation function in which the value of the black position was subtracted from that of the white position. Material was counted according to the usual chess piece relative value (1 point for a pawn, 3 points for a knight or bishop, 5 points for a rook, and 9 points for a queen). He considered some positional factors, subtracting ½ point for each doubled pawn, backward pawn, and isolated pawn; mobility was incorporated by adding 0.1 point for each legal move available.
=== Shannon's maxim === Shannon formulated a version of Kerckhoffs' principle as "The enemy knows the system". In this form it is known as "Shannon's maxim".
=== Miscellaneous === Shannon also contributed to combinatorics and detection theory. His 1948 paper introduced many tools used in combinatorics. He did work on detection theory in 1944, with his work being one of the earliest expositions of the “matched filter” principle. He was known as a successful investor who gave lectures on investing. A report from Barron's on August 11, 1986, detailed the recent performance of 1,026 mutual funds, and Shannon achieved a higher return than 1,025 of them. Comparing the portfolio of Shannon from the late 1950s to 1986, to Warren Buffett's of 1965 to 1995, Shannon had a return of about 28%, compared to 27% for Buffett. One such method of Shannon's was labeled Shannon's demon, which was to form a portfolio of equal parts cash and a stock, and rebalance regularly to take advantage of the stock's randomly jittering price movements. Shannon reportedly long thought of publishing about investing, but ultimately did not, despite giving multiple lectures. He was one of the first investors to download stock prices, and a snapshot of his portfolio in 1981 was found to be $582,717.50, translating to $1.5 million in 2015, excluding another one of his stocks.
== Commemorations ==
=== Shannon centenary ===
The Shannon centenary, 2016, marked the life and influence of Shannon on the hundredth anniversary of his birth on April 30, 1916. It was inspired in part by the Alan Turing Year. An ad hoc committee of the IEEE Information Theory Society including Christina Fragouli, Rüdiger Urbanke, Michelle Effros, Lav Varshney and Sergio Verdú, coordinated worldwide events. The initiative was announced in the History Panel at the 2015 IEEE Information Theory Workshop Jerusalem and the IEEE Information Theory Society newsletter. A detailed listing of confirmed events was available on the website of the IEEE Information Theory Society. Some of the activities included: