Chebyshev, Pafnutii L'vovich

Japanese: チェビシェフ（英語表記）Chebyshev， Pafnutii L'vovich

Born: May 16, 1821, Okatobo
Died: December 8, 1894. St. Petersburg Russian mathematician. In 1832, his family moved to Moscow, and he received his secondary education from a private tutor. His mathematics teacher, PN Pogorelsky, was said to have been a well-known teacher in Moscow at the time. He graduated from Moscow University (1841). While a student, he was awarded a silver medal by the university for his thesis on "Calculating the Roots of Equations." He became a lecturer (47), associate professor (50), and professor (60) at St. Petersburg University, and remained in that position until his retirement in 1880. He initially lectured on advanced algebra and number theory, but later also on integrals, elliptic functions, and difference methods. Much of his work makes use of calculus, but it can be broadly divided into analytical number theory, probability theory, and the theory of best approximations of functions. In probability theory, he generalized the law of large numbers in 1866, and de Moivre-Laplace's central limit theorem in 1887. His theory of function approximation arose from his research into the reciprocating motion of the pistons of steam engines, which he became interested in while studying abroad in 1952. He attempted to approximate the continuous function f ( x ) using the polynomial P ( x ), and it was during this research that he discovered Chebyshev polynomials and the system of orthogonal functions. He is also highly regarded not only for his mathematical discoveries, but also for establishing a group of mathematicians known as the Petersburg School.

Source: Encyclopaedia Britannica Concise Encyclopedia About Encyclopaedia Britannica Concise Encyclopedia Information

Japanese:

[生]1821.5.16. オカトボ
[没]1894.12.8. ペテルブルグ
ロシアの数学者。 1832年，一家がモスクワに移住したので，中等教育を家庭教師によって受ける。彼に数学を教えた P.N.ポゴレルスキーは，当時のモスクワでは名の知られた教師であったという。モスクワ大学卒業 (1841) 。学生時代に『方程式の根の計算』についての論文で，大学より銀賞を与えられた。ペテルブルグ大学講師 (47) ，員外教授 (50) ，教授 (60) となり，80年に退職するまでその職にとどまる。最初は高等代数学，整数論を講義したが，のちに積分，楕円関数，差分法も講義した。彼の仕事は微積分を駆使したものが多いが，大別すると解析的整数論，確率論，関数の最良近似の理論などに分けられる。確率論においては，66年に大数の法則を一般化し，87年にはド・モアブル＝ラプラスの中心極限定理を一般化した。関数近似の理論は，52年に外国に留学して興味をもった蒸気機関のピストンの往復運動の研究から生じた。彼は連続関数 f(x)を多項式 P(x)によって近似しようとし，その研究のなかでチェビシェフの多項式や直交関数系が発見された。また，数学的発見においてだけでなく，ペテルブルグ学派と呼ばれる一群の数学者集団をつくり上げた点においても，高く評価される。

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