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David Joyner
Works at USNA
Attended Georgia Institute of Technology
Lives in arnold, md
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David Joyner

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Rubik's cube humor:-)
John Deering's "Strange Brew" is just what the title says -- a mix of strange and humorous observations.
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+Erno Rubik​, seen this?
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David Joyner

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Elizebeth Friedman biography, "Divine Fire" is out
In previous posts on this blog (for example, Elizebeth Friedman and the Lew Kim Yuen case , Elizebeth Friedman and the Gordon Lim case , Elizebeth Friedman and the Holmwood case , and so on), I'm mentioned some of the events in Elizebeth Friedman's life. Th...
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I finally finished LaTeXing Lester Hill's paper (from the 1920s?) when he discovered error-correcting codes (which he called error-detecting codes, since he did not realize when they were). Essentially, he discovered (about 20 years before Hamming and Golay) cyclic MDS codes without knowing it, and never published his notes. 
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Registration is now open for the 5th annual Kryptos Competition:

KRYPTOS5: A Series of Cryptanalysis Challenges

April 16 – 20, 2015

KRYPTOS5 is a contest open to undergraduate students.  The theme of the contest is centered around the breaking, or cryptanalysis, of ciphers (secret writing). Each challenge presents contestants with a brief scenario together with some ciphertext (encoded message). The goal is to discover the original English plaintext message!

Clues to help break the cipher may be contained in the actual ciphertext or in the details of the accompanying scenario.

While it is not the intent of this contest to test overly technical aspects of cryptanalysis or advanced mathematical algorithms, some familiarity with basic codemaking and codebreaking is certainly helpful. Some useful sources include:



Challenges from last year's contest.
The American Cryptogram Association.

Wikipedia entries for Cryptography and Cryptanalysis
The Code Book by Simon Singh.
Secret History: The Story of Cryptology by Craig Bauer
Codes and Ciphers by R.F. Churchhouse
Codes, Ciphers and Secret Writing by Martin Gardner

We had nearly 100 students participate last year and many have been clamoring for more!  Please announce this contest to your students!  Cool prizes are sent out to first and second place winners!

Visit: http://www.cwu.edu/math/kryptos/ for more information -- including instructions on registering students for the contest and a one-page flyer that you can post around your department or campus.

Thank you,

Stuart Boersma , Central Washington University
Cheryl Beaver, Western Oregon University
 

KRYPTOS is sponsored by the Pacific Northwest Section of the Mathematical Association of America together with Central Washington University and Western Oregon University.
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David Joyner

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Amusing paradox, thanks to futilitycloset.com. I guess the simplest explanation of the contradiction is to use the usual calculus II formula for the arc length. Is there a simpler one?
The Pythagoras Paradox. http://commons.wikimedia.org/wiki/Category:Mathematical_paradoxes#. Draw a right triangle whose legs a and b each measure 1. Draw d and e to complete a unit square. Clearly d + e = 2. Now if we cut a “step” into the square as shown, then f + h = 1 and g + i = 1, ...
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+Ramsay Dyer Also, the bounded area between the steps and the diagonal converges to 0 as the number of steps approaches infinity (I believe the area is 1/2^(2^(n-1))). I think that's a clearer way of explaining the same concept.
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Interesting optical illusion. White+gold or Blue+brown?
http://swiked.tumblr.com/post/112073818575/guys-please-help-me-is-this-dress-white-and
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Curious. For me, it's blue + black from start to finish.
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The Colmar Incident
The Colmar incident concerns a true episode in World War II which took place in and around Colmar, France , in which a top-secret cryptographic machine called a SIGABA (or an ECM Mark II ) went missing. This event is now declassified and this blog post foll...
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David Joyner

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Elizebeth Friedman was one of America's greatest cryptographers in the early- to mid-1900s. She worked during the Prohibition era for the Department of the Treasury and the Coast Guard and, at various times during World War I and World War II, for the War Department. This monograph concerns her personal life and professional work for the Coast Guard on liquor and narcotics smuggling, up to the late 1930s.

The book is out now: Divine Fire on amazon.com, for about $5. More precisely, it is priced at 1 penny above the minimum amazon.com cost. I think if you go to createspace.com you can buy it even cheaper, but shipping costs might be different. 
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Interesting article on gender differences.
How do teen math prodigies from the 1970s view success at mid-life? The answer differs according to gender.
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I just read it as a statistically study of what men vs women view as success.

Better math education can't hurt though:-)
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A mate-in-2 by Sam Loyd, thanks to futilitycloset.com. I thought this one was cleverly constructed. It's trickier than first meets the eye:-)
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This is a really simple clever proof of a very easily stated fact in mathematics, thanks to futilitycloset.com:
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Good article on adjunct instructors.
Teaching college is no longer a middle-class job, and everyone paying tuition should care.
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Have him in circles
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Education
  • Georgia Institute of Technology
    math
  • University of Maryland, College Park
    math
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Male
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math, writing, tech, edu, ...
Introduction
Enjoy tinkering with mathematics, writing, Sage (www.sagemath.org), video, chess, and photography. Interested in math education-related and open-source software issues.
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have managed to stay off facebook
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Occupation
math prof
Employment
  • USNA
    math prof, present
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arnold, md
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mountain view, ca - kent, wa - decatur, ga - princeton, nj - san diego, ca
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I have used All for the Pet for years and never once had rude service. The store doesn't even open until 9am and Lisa often comes in early to help out people who want to drop off their pet before going to work. I think she does a good job with my pets and her prices are reasonable.
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