Keith Kendig – författare
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Hassler Whitney was a giant of twentieth-century mathematics. This biography paints a picture of him and includes dozens of revealing anecdotes. Mathematically, he had a rare detector that went off whenever he spotted a piece of mathematical gold, and he would then draw countless pictures, gradually forging a path from hunch to proof. This geometric path is seldom reflected in the rigor of his formal papers, but thanks to a close friendship and many conversations over decades, author Kendig was able to see how he actually worked. This book shows this through accessible accounts of his major mathematical contributions, with figures copiously supplied.Whitney is probably best known for introducing the grandfather of today's innumerable embedding theorems--his strong embedding theorem stating that any smooth manifold can be smoothly embedded in a Euclidean space of twice the manifold's dimension. This in turn led to several standard techniques used every day in algebraic topology. Whitney also established the fundamentals of graph theory, the four-color problem, matroids, extending smooth functions, and singularities of smooth functions. He almost never used complicated technical machinery, so most of his work is accessible to a general reader with a modest mathematical background.His math-music connection was intense: He played piano, violin, and viola and won ``best composition of the year'' while earning a Bachelor's degree in music at Yale. He was an accomplished mountain climber, and as a tinkerer, at age sixteen he built the large-format camera used to take this book's cover photograph. Whitney's family generously provided dozens of photographs appearing here for the very first time. This biography is a revealing portrait of a fascinating personality and a titan of twentieth-century mathematics.
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Challenge: Can you find all the integers $a$, $b$, $c$ satisfying $2a^{2} + 3b^{2} = 5c^{2}$? Looks simple, and there are in fact a number of easy solutions. But most of them turn out to be anything but obvious! There are infinitely many possibilities, and as any computer will tell you, each of $a$, $b$, $c$ will usually be large. So the challenge remains ... Find all integers$a$, $b$, $c$satisfying$2a^{2} + 3b^{2} = 5c^{2}$.A major advance in number theory means this book can give an easy answer to this and countless similar questions. The idea behind the approach is transforming a degree-two equation in integer variables $a$, $b$, $c$ into a plane curve defined by a polynomial. Working with the curve makes obtaining solutions far easier, and the geometric solutions then get translated back into integers. This method morphs hard problems into routine ones and typically requires no more than high school math. (The complete solution to $2a^{2} + 3b^{2} = 5c^{2}$ is included in the book.) In addition to equations of degree two, the book addresses degree-three equations--a branch of number theory that is today something of a cottage industry, and these problems translate into ""elliptic curves''. This important part of the book includes many pictures along with the exposition, making the material meaningful and easy to grasp.This book will fit nicely into an introductory course on number theory. In addition, the many solved examples, illustrations, and exercises make self-studying the book an option for students, thus becoming a natural candidate for a capstone course.