Mathematical Theory of Claude Shannon (2001)
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Mathematical Theory of Claude Shannon A study of the style and context of his work up to the genesis of information theory. by Eugene Chiu, Jocelyn Lin, Brok Mcferron, Noshirwan Petigara, Satwiksai Seshasai 6.933J / STS.420J The Structure of Engineering Revolutions Table of Contents Acknowledgements............................................................................................................................................3 Introduction........................................................................................................................................................4 Methodology ..................................................................................................................................................7 Information Theory...........................................................................................................................................8 Information Theory before Shannon.........................................................................................................8 What was Missing........................................................................................................................................15 1948 Mathematical theory of communication ........................................................................................16 The Shannon Methodology .......................................................................................................................19 Shannon as the architect.............................................................................................................................19 Switching Theory .............................................................................................................................................22 Background and Contemporary Work.....................................................................................................22 Building Blocks to Shannon's Master's Thesis........................................................................................23 A Symbolic Analysis of Relay and Switching Circuits ...........................................................................26 Theorems....................................................................................................................................28 Negation Theorems ..................................................................................................................28 Analogue Between the Calculus of Propositions and the Symbolic Relay Analysis..........................29 An Example of a Synthesis Problem........................................................................................................29 Popular Recognition ...................................................................................................................................31 Genetics.............................................................................................................................................................34 An Algebra for Theoretical Genetics, the beginnings ...........................................................................34 History of population genetics ..................................................................................................................35 Eugenics...................................................................................................................................................35 Genetics in late 1930’s............................................................................................................................37 Genetics in early 1940’s .........................................................................................................................38 Vannevar Bush, Claude Shannon, and genetics......................................................................................38 Shannon’s Ph.D...........................................................................................................................................40 Algebraic details...........................................................................................................................................41 Analysis and Comparison...........................................................................................................................43 A Dead End .................................................................................................................................................43 Cryptography....................................................................................................................................................47 Relation to Information Theory................................................................................................................47 Vernam System............................................................................................................................................50 Link to Information Theory ......................................................................................................................52 Shannon's Style.................................................................................................................................................54 Collaboration................................................................................................................................................54 Advising ........................................................................................................................................................56 The "great gadgeteer" .................................................................................................................................57 Application of his work..............................................................................................................................60 Awards and Recognition ............................................................................................................................61 Conclusion ........................................................................................................................................................63 References.........................................................................................................................................................65 Correspondences.........................................................................................................................................65 Interviews .....................................................................................................................................................65 Publications..................................................................................................................................................66 2 Acknowledgements We would like to thank professors Robert Fano, Bob Gallagher, Chris Kaiser, Charles Vest and Hartley Rogers for their academic and personal insight into Claude Shannon’s work and the fields of switching theory, genetics and information theory. Shannon’s advisees Trenchard More, William Sutherland and Henry Ernst provided us with a unique perspective on working with Dr. Shannon. Betty Shannon graciously discussed her husband’s personality and work. MIT staff Be Blackburn and Laura Mersky helped facilitate our research. The staff of the MIT Archives and Library of Congress were instrumental in locating important documents and correspondences between Shannon and his colleagues. Professor David Mindell and Teaching Assistant Chen-Pang Yeang went beyond their roles as instructors and provided us with insight into their own research on this topic. Finally, we would also like to thank Peter Elias, who before passing away on Dec. 7, 2001 allowed us to search through his extensive archive of books and documents related to Claude Shannon and his fields. This paper is dedicated to his memory and the memory of Claude Shannon, who passed away on February 24, 2001. 3 Introduction When Trenchard More first met Claude Elwood Shannon, he was taking his oral exam for his Ph. D at the Massachusetts Institute of Technology1. The written exam was especially difficult at the time, recalled More, so doing well on the oral portion of the exam was vital. Shannon had agreed to be on More's committee because More was a TA under Sam Caldwell, an advisor for Shannon's own Master's thesis. The questions Shannon asked were drastically different from the rest and concentrated on the mathematical ideas behind the topics being discussed. Shannon was “after the ways of thought,” said More. He cared more about how More was thinking and whether he understood the fundamental mathematical concepts behind his research. Shannon felt that someone who really understood ideas could recreate them before your eyes, related More. Fortunately, despite having stumbled through the technical details in the written and oral exam, More had developed a solid understanding of the mathematical concepts and passed the oral exams by successfully answering Shannon's questions. He remembered another student meeting a different fate with Shannon - despite his perfect GPA, the student could not answer Shannon's questions, and it was revealed that he was simply memorizing concepts. The focus Shannon displayed in his questioning of More was representative of the guiding vision which drove much of his work. The most popular and revolutionary pieces of Shannon's work came very early