Recent Posts http://www.mathblogging.org/scripts/feed.php 2013-05-22T06:30:29-04:00 No copyright asserted over individual posts; see original posts for copyright and/or licensing. Mathblogging.org Atom serializer http://www.mathblogging.org/post/52905 2013-05-31T01:00:00-04:00 Unknown

Researchers from Brazil's Universidade Estadual de Campinas used a computer simulation to confirm paleontologist Stephen J. Gould's prediction that it is evolutionarily advantageous for cicadas to emerge at intervals lasting a prime number of years.

http://www.mathblogging.org/post/53604 2013-05-22T05:17:26-04:00 david

article on category theory

http://www.mathblogging.org/post/53603 2013-05-22T05:00:00-04:00 Colin

This came up in class, and took me several attempts, so I thought I’d share it. The question asks about an ellipse with equation $9x^2 + 25y^2 = 225$, with foci $A$ and $B$ at $(\pm4,0)$ – the challenge is to prove that the normal to the ellipse at a point $P$ bisects the angle $APB$. It’s a vile, vile question, and not something that should be left alone near teenagers. Here’s the proof. Please make sure your seatbelt is securely fastened. The formula book give you: the […]

http://www.mathblogging.org/post/53602 2013-05-22T03:50:59-04:00 Nathan Yau

About 35,000 meteorites have been recorded since 2500 BC, and a little over 1,000 of them were seen while they …

http://www.mathblogging.org/post/53600 2013-05-22T03:50:11-04:00 Peter Cameron

The last chapter of Mathematical Structures was about how to spot false proofs. Of course, I am not the first to do this. A curious chain (I may tell about this later) led me to The Sophismata of Richard Kilvington. … Continue reading →

http://www.mathblogging.org/post/53601 2013-05-22T03:00:04-04:00 ^DiAmOnD^

Un bonito (y sencillo) ejercicio relacionado con el principio de inducción consiste en demostrar que el cuadrado de la suma de cualquier conjunto de enteros positivos consecutivos que comience en el 1 es igual a la suma de los cubos de dichos números. Es decir, que para todo se cumple que Podéis intentar resolverlo vosotros [...]Entra en Gaussianos si quieres hacer alg&uacute;n comentario sobre este art&iacute;culo, consultar entradas anteriores o enviarnos un mensaje.<br><br>Construye t&uacute; </br> </br> […]

http://www.mathblogging.org/post/53599 2013-05-22T02:30:00-04:00 Mathematical Association of America

862 = 2 x 431.<br /><br />862 is a number whose sum of divisors is a fourth power: 1 + 2 + 431 + 862 = 1296 = 64.<br /><br />862 is the maximum number of regions into which 41 lines divide the plane.<br /><br />862 has the representation 862 = 25 x 33 - 2.<br /><br />862 is a divisor of 955 - 1.<br /><br /><br />Source: What's Special About This Number?

http://www.mathblogging.org/post/53597 2013-05-22T01:01:40-04:00 Presh Talwalkar

Pound Foolish by Helaine Olen is an excellent exposé of the personal finance industry. After reading it, you&#8217;ll never look at a talking head on TV the same way. It seems many personal finance advisors have an attitude of &#8220;Do what I say, not what I do.&#8221; Here are a few examples from the book. [...]

http://www.mathblogging.org/post/53598 2013-05-22T01:01:33-04:00 Presh Talwalkar

Bad decisions 1. JC Penny uses fake regular prices so sales look better 2. If you&#8217;re not a pure-math person or an expert programmer, that&#8217;s all right, because you can be on a team with people who are&#8221; 3. Thinking everything at Subway is healthy 4. Replacing expensive habits with slightly less expensive ones 5. [...]

http://www.mathblogging.org/post/53596 2013-05-22T01:01:00-04:00 Igor

Karsten Fyhn&nbsp;just let me know of their recent article and attendant code repository.&nbsp; <br /> Compressive Parameter Estimation for Sparse Translation-Invariant Signals Using Polar Interpolation&nbsp;by&nbsp;Karsten Fyhn, Marco F. Duarte and Søren H. Jensen <br /> We propose new compressive parameter estimation algorithms that make use of polar interpolation to improve the estimator precision. Moreover, we evaluate six algorithms for estimation of parameters in sparse translation-invariant […]

http://www.mathblogging.org/post/53606 2013-05-22T01:00:00-04:00 Barbara Schapira

La deuxième journée sur la parité en mathématique aura lieu le 24 juin prochain à l'Institut Henri Poincaré à Paris. Les inscriptions sont ouvertes. Venez nombreux-ses ! - Billets des habitués

http://www.mathblogging.org/post/53605 2013-05-22T01:00:00-04:00 Un jour une brève

Les télécommunications sont devenues indispensables dans notre vie quotidienne et l'envoi de messages de plus en plus volumineux demandent un débit toujours plus rapide... - Mathématiques de la Planète Terre / Mathématiques de la planète Terre, Mathématique de la planète Terre, carrousel

http://www.mathblogging.org/post/53595 2013-05-22T00:53:00-04:00 Joseph

Felix Salmon:<br /><br />My point here is that technology has a tendency to create its own norms. The classic example is the automobile — a technology which kills more than 30,000 Americans every year. From the 1930s through the 1990s, societal norms about who roads belonged to, and what people should do on them, were turned on their head thanks to the new technology. The dangerous new activity allowed by the new technology became the privileged norm, to the point at which just about all other road-based […]

http://www.mathblogging.org/post/53594 2013-05-22T00:00:00-04:00 Unknown

In designing his 'f3' collection of rotomolded furniture, Fabio Novembre adhered to the principle of 'form follows function' and derived the shapes of the pieces from mathematical surfaces.

http://www.mathblogging.org/post/53593 2013-05-21T23:59:51-04:00 Derek Smith

Having spent time in the Air Force and then developing software as a government contractor, I&#8217;ve survived more than my share of bad presentations. During this time I began reading the works of the statistician Edward Tufte[wiki]. I&#8217;d like to &#8230; Continue reading &#8594;

http://www.mathblogging.org/post/53592 2013-05-21T23:01:20-04:00 venneblock

I&#8217;ve learned one thing in my life — the least funny math jokes are the ones you have to explain. As E. B. White said, Humor can be dissected as a frog can, but the thing dies in the process, and the innards are discouraging to any but the pure scientific mind. Matt Parker, who did [&#8230;]

http://www.mathblogging.org/post/53591 2013-05-21T22:15:37-04:00 samjshah

At the end of last year, a science teacher and I came up with the idea of creating a math-science journal for students to publish their work in. Our school has a literary and art journal and even a foreign language journal. But there is no forum for students to show off their more mathysciency [&#8230;]

http://www.mathblogging.org/post/53589 2013-05-21T22:02:06-04:00 Unknown

Many a time less is more, hence I shall keep the introductions real<br />short and sweet.<br /><br /><br />WELCOME.<br /><br /><br />"Everything should be made as simple as possible, but not simpler."-Albert Einstein

http://www.mathblogging.org/post/53590 2013-05-21T22:01:24-04:00 Unknown

<br /><br />CLICK ON IMAGE TO ENLARGE

http://www.mathblogging.org/post/53588 2013-05-21T21:42:00-04:00 Michael Pershan

The kids are confident<br /> <br /> I recently gave my students&nbsp;another survey. At the time of the survey, the students had just studied exponents and were about to begin multiplying/factoring polynomials. To emphasize: they've never studied multiplying/factoring in a formal setting. The second half of this survey is what you folks call a pre-assessment or something.<br /> <br /> This response from a student -- let's call him Mike -- is especially interesting. <br /> <br /> Mike nails the first three questions. A […]

http://www.mathblogging.org/post/53587 2013-05-21T21:38:14-04:00 mpershan

This is from yesterday&#8217;s survey, which was discussed over at this post. What do you make of the responses, particularly the differences between  (2a+6) in the first response, and (2x+49) in the second?

http://www.mathblogging.org/post/53586 2013-05-21T21:34:11-04:00 Jon Cogburn

Christ, it's depressing how smart one can be in one area while believing the most transparently idiotic things in others (especially when moral culpability is involved). Read THIS COLUMN (&quot;MOOC Professors Claim No Responsibility for How Courses Are Used&quot;) for yet more evidence concerning the correctness of John Calvin on...

http://www.mathblogging.org/post/53584 2013-05-21T21:10:12-04:00 MathyNick

Using 1, 2, and 3, how many numbers can be formed if repetition is not allowed?

http://www.mathblogging.org/post/53585 2013-05-21T21:10:07-04:00 Pip

Why the recent breakthrough is important Yitang Zhang, of the University of New Hampshire, has apparently proved a finite approximation to the famous Twin Prime Conjecture. This is a result of the first order. After ten days of progressively more detailed news, including today&#8217;s article in the New York Times, Zhang&#8217;s 56-page preprint has just [&#8230;]

http://www.mathblogging.org/post/53583 2013-05-21T20:30:17-04:00 Terence Tao

Vitaly Bergelson, Tamar Ziegler, and I have just uploaded to the arXiv our joint paper &#8220;Multiple recurrence and convergence results associated to -actions&#8220;. This paper is primarily concerned with limit formulae in the theory of multiple recurrence in ergodic theory. Perhaps the most basic formula of this type is the mean ergodic theorem, which (among [&#8230;]

http://www.mathblogging.org/post/53581 2013-05-21T20:19:41-04:00 jnewman85

(and assessments). Yeah, it&#8217;s the end of my 2nd year of teaching Precalculus, Physics, and Chemistry, and I figure I should be able to post my lessons without too much shame. Actually, I am embarrassed of some things, because I&#8217;d like to &#8230; Continue reading &#8594;

http://www.mathblogging.org/post/53582 2013-05-21T20:10:05-04:00 Unknown

An Unheralded Breakthrough: The Rosetta Stone of Mathematics: Edward Frenkel: Deligne’s most spectacular results are on the interface of two areas of mathematics: number theory and geometry. At first glance, the two subjects appear to be light-years apart. As the name suggests, number theory is the study of numbers, such as the familiar natural numbers (1, 2, 3, and so on) and fractions, or more exotic ones, such as the square root of two. Geometry, on the other hand, studies shapes, such as […]

http://www.mathblogging.org/post/53579 2013-05-21T20:08:46-04:00 AfterMath

Suppose I gave you some red fingerpaint and asked you to make all the colors you could from this paint. You&#8217;d probably come up with a diverse collection of pinks, reds and burgendys &#8211; going through the range of reds &#8230; Continue reading &#8594;

http://www.mathblogging.org/post/53580 2013-05-21T20:00:00-04:00 Pat B

The Le Petit Journal cover, on 1912 April 21, shows eclipse watchers in 1912 along with the solar eclipse of May 22, 1724, the previous total solar eclipse visible from Paris, France *Wik<br /><br /><br />“Biographical history, as taught in our public schools, is still largely a history of boneheads:ridiculous kings and queens, paranoid political leaders, compulsive voyagers, ignorant generals&nbsp;- the flotsam and jetsam of historical currents.&nbsp;The men who radically altered history,&nbsp;the great […]

http://www.mathblogging.org/post/53578 2013-05-21T18:47:38-04:00 porton

Today I&#8217;ve discovered a new kind of product of funcoids which I call &#8220;simple product&#8221;. It is defined by the formulas: and . Please read my book.