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group

(Encyclopedia)group, in mathematics, system consisting of a set of elements and a binary operation a∘b defined for combining two elements such that the following requirements are satisfied: (1) The set is closed ...

Stifter, Adalbert

(Encyclopedia)Stifter, Adalbert äˈdälbĕrt shtĭfˈtər [key], 1805–68, Austrian writer, b. Bohemia. Learned in law, mathematics, and science and accomplished as an artist, he was a tutor to important families...

secant

(Encyclopedia)secant, in mathematics. 1 In geometry, a secant is a straight line cutting a curve or surface. If it intersects the curve in two different points, as in the secant of a circle, the segment of the seca...

Fibonacci, Leonardo

(Encyclopedia)Fibonacci, Leonardo lāōnärˈdō fēbōnätˈchē [key], b. c.1170, d. after 1240, Italian mathematician, known also as Leonardo da Pisa. In Liber abaci (1202, 2d ed. 1228), for centuries a standard...

Posidonius

(Encyclopedia)Posidonius pōsēdōˈnēəs [key], c.135–c.51 b.c., Greek Stoic philosopher, b. Apamea, Syria. He settled in Rhodes after extensive travels. Noted for his learning, Posidonius gave new life to Stoi...

Burritt, Elihu

(Encyclopedia)Burritt, Elihu, 1810–79, American reformer, b. New Britain, Conn. A blacksmith, he studied mathematics, languages, and geography and became known as “the learned blacksmith.” Profoundly idealist...

Freundlich, Erwin Finlay

(Encyclopedia)Freundlich, Erwin Finlay froindˈlĭkh [key], 1885–1964, German astronomer. Freundlich obtained a doctorate in mathematics at Göttingen, then joined the Royal Observatory at Berlin, where he worked...

plane

(Encyclopedia)plane, in mathematics, flat surface of infinite extent but no thickness. An example of a plane, or more exactly of a bounded portion of a plane, is the surface forming one face, or side, of a cube. A ...

National Defense Education Act

(Encyclopedia)National Defense Education Act (NDEA), federal legislation passed in 1958 providing aid to education in the United States at all levels, public and private. NDEA was instituted primarily to stimulate ...

Parisi, Giorgio

(Encyclopedia)Parisi, Giorgio, 1948–, Italian physicist, Ph.D. Sapienza University of Rome, 1970. Parisi is Professor of Theoretical Physics at Sapienza University....