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584 posts tagged with Math.

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## Quite a day for analytic number theory

This afternoon, Yitang Zhang of the University of New Hampshire gave a special seminar at Harvard, in which he announced that he had proved that there are infinitely many pairs of prime numbers separated by no more than 70,000,000, a result differing only by a constant factor from the venerable twin prime conjecture. Dan Goldston, who together with Yildirim and Pintz made the last major advance on prime gaps, said, ""I was doubtful I would ever live to see this result." Not enough excitement for one day? Harald Helfgott has just posted to the arXiv a proof of the ternary Goldbach conjecture: every odd number is the sum of three primes.

## Proof and Community Standards

In August of last year, mathematician Shinichi Mochizuki reported that he had solved one of the great puzzles of number theory: the ABC conjecture (previously on Metafilter). Almost a year later, no one else knows whether he has succeeded. No one can understand his proof.

## What if P=NP?

## Math and parenting

Division of labor in child care: A game-theoretic approach The analysis shows that it is difficult to achieve the equilibrium of equal sharing of child care, even when this is the preference of the parents. This leads to a discussion of alterations and meta-strategies for couples who want to share care equally. Gender differences between parents are also modeled, including the impact these have on outcomes and equilibria.Full text PDF

## Why Philosophers Should Care About Computational Complexity

"One might think that, once we know something is computable, how efficiently it can be computed is a practical question with little further philosophical importance. In this essay, I offer a detailed case that one would be wrong. In particular, I argue that computational complexity theory---the field that studies the resources (such as time, space, and randomness) needed to solve computational problems---leads to new perspectives on the nature of mathematical knowledge, the strong AI debate, computationalism, the problem of logical omniscience, Hume's problem of induction, Goodman's grue riddle, the foundations of quantum mechanics, economic rationality, closed timelike curves, and several other topics of philosophical interest. I end by discussing aspects of complexity theory itself that could benefit from philosophical analysis."

## The map of music

Every Noise At Once. A map of musical genres, built by Glenn McDonald of The War Against Silence and the Echo Nest. Click on a genre name to hear a sound sample, or pop it open to see a map of bands within that genre.

## Triple Gear

Mathematicians Henry Segerman and Saul Schleimer have produced a triple gear, three linked gears in space that can rotate together. A short writeup of the topology and geometry behind the triple gear on the arXiv.

## 100% Prime

"Each prime number is represented by a bright, white square, whereas a non-prime ("composite") is grey. Visitors can select difference spatial arrangements of these numbers, ranging from several variants of the well-known Ulam Spiral, over the Archimedian spiral, to the more sophisticated 3D Hilbert curves." [more inside]

## Great Scientist ≠ Good at Math?

Do you need to know math to do science? Harvard professor emeritus E. O. Wilson says, "no." Jeremy Fox, an Associate Professor of Population Ecology at the University of Calgary disagrees.

## A Circular Diversion

The Circle Drawing Experiment. You've seen competitive circle drawing (previously). Now try your own hand (mouse?) at drawing a freehand circle. Bonus: cats.

## Computerized Math, Formal Proofs and Alternative Logic

Using computer systems for doing mathematical proofs - "With the proliferation of computer-assisted proofs that are all but impossible to check by hand, Hales thinks computers must become the judge." [more inside]

## That Makes It Invertible! (by The Three Directions)

Three professors at Harvey Mudd College wanted to do something special to mark the final lecture of Math 40: Linear Algebra that their students could relate to. The result: they transformed themselves into The Three Directions and performed "That Makes It Invertible!" for their class, complete with choreography and bad math puns. (SLYT)

## So what is it smart guy?

The facebook question that has everyone stirred up... I got 9. I am a fifty-one year old white guy. Did new math f-ck me up? [more inside]

## Using pies to calculate pi

Ahead of Pi Day (March 14), Matt Parker tries to accurately calculate pi using pies. [SLYT] An extended version of the video will be uploaded on Pi Day, but here's your chance to go out and buy pies before that.
(Video runs 3 minutes, 14 seconds.)

## Give or take

The origins of plus and minus signs - "There be other 2 signes in often use of which the first is made thus + and betokeneth more: the other is thus made – and betokeneth lesse."

## Aspiring Animators & Game Designers, Study Your Calculus & Combinatorics

Every film Pixar has produced has landed in the top fifty highest-grossing animated films of all time. What's their secret? Mathematics. Oh, and 22 Rules of Storytelling. [more inside]

## They said something about "math," but nothing about LSD.

## Oliver Heaviside

Surely you've heard of the physicist Maxwell, but what about Oliver Heaviside? Oliver Heaviside: A first-rate oddity.

## OMG SCIENCE!

Henry Reich of Minute Physics shares his favorite science blogs, video channels, and other resources on the web. (Minute Physics previously) [more inside]

## the power and beauty of mathematics

## Episciences Project

Tim Gowers has announced a series of arXiv overlay journals called the Episciences Project that aim to exclude existing publishers from research publication in mathematics. As arXiv overlays, the Episciences Project avoids the editing and typesetting costs that existing open-access journals pay for using article processing charges. The French Centre pour la Communication Scientifique Directe (CCSD) is backing the remaining expenses, such as developing the platform. [more inside]

## Love in the Time of Neuroinformatics

"The models we discuss belong to the class of two-variable systems with one delay for which appropriate delay stabilizes an unstable steady state. We formulate a theorem and prove that stabilization takes place in our case. We conclude that considerable (meaning large enough, but not too large) values of time delay involved in the model can stabilize love affairs dynamics." [more inside]

## loop-a-doop-a, loop-a-doop-a, loop-a-doop-a, squiggly dot!

Doodle Music [slyt]

## Teaching Computers to Hear Emotions

New research can detect five different emotions with 81 percent accuracy. [Additional project information].

## Numberphile: videos about numbers and stuff

Numberphile is a website containing short videos (approx. 5-10 min.) about numbers and stuff. Mathematicians and physicists play around with the tools of their trade and explain things in simple, clear language. Learn things you didn't know you were interested in! Find out why 493-7775 is a pretty cool phone number! What's the significance of 42, anyway? What the heck is a vampire number? Why does Pac-Man have only 255 screens?
Suitable for viewing by everyone from intelligent and curious middle-schoolers to math-impaired adults. Browse their YouTube channel here. (Via)

## My God, its full of stars!

## The Museum of Mathematics

Last night was the grand opening of the Museum of Mathematics in New York City, the only museum of its kind in North America. The video is narrated by MoMath's chief of content, mathematical sculptor George Hart (better known in some circles as Vi Hart's dad.) The sculpture of the space of three-note chords in the video is based on the work of Dmitri Tymoczko, and the lovely curved hammock of strings a visitor is sitting in at the end is a ruled quadric surface. Many more videos at the Museum of Mathematics YouTube channel. Coverage from the New Scientist. (Previously on MetaFilter.)

## Any yokel with a computer can have a college football ranking system

He is not the only one. Computer rankings are proliferating, said Kenneth Massey, a professor of math at Carson-Newman in Jefferson City, Tenn., who has been ranking teams since 1995. “When I started, there were six or seven,” he said. “But every year, it gets bigger and bigger.” Massey currently tracks more than 100 college football rankings.

With so many competitors, what is the appeal of creating one’s own rankings?

“It’s kind of a nerdy hobby,” Massey said. “It combines sports with math and computers, three things that don’t ordinarily go together.” [more inside]

With so many competitors, what is the appeal of creating one’s own rankings?

“It’s kind of a nerdy hobby,” Massey said. “It combines sports with math and computers, three things that don’t ordinarily go together.” [more inside]

## Making things with Maths

## An example of "order out of chaos"

"Draw some random points on a piece of paper and join them up to make a random polygon. Find all the midpoints and connecting them up to give a new shape, and repeat. The resulting shape will get smaller and smaller, and will tend towards an ellipse!" [code to make this in Mathematica] [a version which allows you to watch the process step by step, with 10 vertices or 100]

## direct realism

The Nature of Computation - Intellects Vast and Warm and Sympathetic: "I hand you a network or graph, and ask whether there is a path through the network that crosses each edge exactly once, returning to its starting point. (That is, I ask whether there is a 'Eulerian' cycle.) Then I hand you another network, and ask whether there is a path which visits each node exactly once. (That is, I ask whether there is a 'Hamiltonian' cycle.) How hard is it to answer me?" (via) [more inside]

## Math Publishing for Dummies!

Mathgen is a program to randomly generate professional-looking mathematics papers, including theorems, proofs, equations, discussion, and references. Try Mathgen for yourself! (PDF example) It’s a fork of SCIgen, a program which generates random papers in computer science. Surprisingly, Mathgen has already had it's first randomly-generated paper accepted by a "journal".

## The strange case of The Pigeon-hole Principle

It's Saturday; why not think about the pigeonhole principle? Here are problems and more problems and what you might call a problem with the principle itself as it is often stated.

## Ein Beitrag zur Optik der Farbanstriche

For years now, the primary way of representing and storing color on a computer display has been to define it as existing in three dimensions: Red, Green, and Blue. What if that's wrong? “While the appearance of a color on a screen can be described in three dimensions, the blending of color actually is happening in a six dimensional space,” How Fifty-Three, developers of the iPad painting app Paper, used a theory of paint optics from 1931 to develop a better color mixer.

## The Fifth problem: Math & Anti-Semitism in the Soviet Union

The Fifth Problem: "If this were a boxing match, with one of the boxers pressed in the corner, bloodied, desperately trying to hold his own against the barrage of punches falling on him (many of them below the belt, I might add), that would be the equivalent of the final, deadly, blow. The problem looked innocent enough at first glance: given a circle and two points on the plane outside the circle, construct another circle passing trough those two points and touching the first circle at one point." Edward Frenkel, now Professor of Mathematics at the University of California, Berkeley, details the curiously baroque way Moscow State University chose to discriminate against talented Jewish math students: By quizzing them with fiendishly difficult math problems with deceptively simple solutions that are nearly impossible to find. [more inside]

## Factor Conga

Animation of prime factorization of the integers based on Brent Yorgey's factorization diagrams, described here. [via Data Pointed, previously.]

## There is Nothing New Under the Sun

*She sat zazen, concentrating on not concentrating, until it was time to prepare for the appointment. Sitting seemed to produce the usual serenity, put everything in perspective. Her hand did not tremble as she applied her make-up; tranquil features looked back at her from the mirror. She was mildly surprised, in fact, at just how calm she was, until she got out of the hotel elevator at the garage level and the mugger made his play. She killed him instead of disabling him. Which was obviously not a measured, balanced action--the official fuss and paperwork could make her late. Annoyed at herself, she stuffed the corpse under a shiny new Westinghouse roadable whose owner she knew to be in Luna, and continued on to her own car. This would have to be squared later, and it would cost. No help for it--she fought to regain at least the semblance of tranquillity as her car emerged from the garage and turned north. Nothing must interfere with this meeting, or with her role in it.*"Melancholy Elephants," an enthralling, Hugo Award-winning short story by Spider Robinson about a disciplined operative, a powerful senator, and a crucial mission to preserve humanity's most precious resource. (some spoilers inside) [more inside]

## no stairway?

Q: How many miles is it to the crab nebula? How does one even figure this out?
A: The cosmic distance ladder! Here's a talk by Fields medalist Terrence Tao on methods for indirect calculation of distances to astronomical objects. Here's Tao's blog post on the subject, including the slides for the talk. And here's a Wikipedia page. [more inside]

## Boaler and the math wars

"Milgram and Bishop are opposed to reforms of mathematics teaching and support the continuation of a model in which students learn mathematics without engaging in realistic problems or discussing mathematical methods. They are, of course, entitled to this opinion, and there has been an ongoing, spirited academic debate about mathematics learning for a number of years. But Milgram and Bishop have gone beyond the bounds of reasoned discourse in a campaign to systematically suppress empirical evidence that contradicts their stance. Academic disagreement is an inevitable consequence of academic freedom, and I welcome it. However, responsible disagreement and academic bullying are not the same thing. Milgram and Bishop have engaged in a range of tactics to discredit me and damage my work which I have now decided to make public." Jo Boaler, professor of mathematics education at Stanford, accuses two mathematicians, one her colleague of Stanford, of unethical attempts to discredit her research, which supports "active engagement" with mathematics (aka "reform math") over the more traditional "practicing procedures" approach. [more inside]

## Smoothlife

SmoothLife is a continuous version of John Conway's Game of Life. When you tire of watching the hypnotic video you can read a technical description of SmoothLife on the arXiv. Then you can watch more videos of SmoothLife.

## weee eigenvectors

Eigenfaces for facial recognition. (

*This post assumes familiarity with the terminology and notation of linear algebra, particularly inner product spaces.*)## What is the smallest prime?

What is the smallest prime? "It seems that the number two should be the obvious answer, and today it is, but it was not always so. There were times when and mathematicians for whom the numbers one and three were acceptable answers. To find the first prime, we must also know what the first positive integer is. Surprisingly, with the definitions used at various times throughout history, one was often not the first positive integer (some started with two, and a few with three). In this article, we survey the history of the primality of one, from the ancient Greeks to modern times. We will discuss some of the reasons definitions changed, and provide several examples. We will also discuss the last significant mathematicians to list the number one as prime."

## Robert MacPherson interviewed

Robert MacPherson interviewed as part of the Simons Foundation's Science Lives series. MacPherson is among the founders of the modern theory of

*singularities*, points like a kink in a curve where the geometry of a space stops being smooth and starts behaving badly. In the interview, MacPherson talks about cultural differences between math and music, his frustration with high school math, growing up gay in the South and life as a gay man in the scientific community, smuggling $23,000 in cash into post-Soviet Russia to help mathematicians there keep the lights on, catastrophe theory, perverse sheaves, how to be a successful graduate student, stuttering, and of course the development of the intersection homology theory for which he is most well-known.## Making Math Fun

Is your elementary school youngster struggling with math? Are they a visual person? Would math games and videos help them learn? Enter Math Playground, to assist with problem solving and real world math. Try the enticing logic game Sugar, Sugar or beef up your math word problem skills. There are plenty of games to help educate while entertaining.

## I ♥ Cardioids

I ♥ Cardioids, Vi Hart's condensed awesome tackles parabolas, cardioids, circles and more. Related: Part 1 of Rolling Circles and Balls.

## While almost unknown to Americans, many Europeans have treasured these portraits

Cliff Stoll makes glass Klein bottles. He also sells imported portraits of Gauss.

## To Infinity and Somewhat Past That!

Are there as many odd numbers as there are all numbers? Can one infinity be bigger than another? TED Ed and Minute Physics both take a look at some of the mind boggling realities of Infinity.

## William Thurston

"The real satisfaction from mathematics is in learning from others and sharing with others." William Thurston, one of the greatest mathematicians of the 20th century, has died. He revolutionized topology and geometry, insisting always that geometric intuition and understanding played just as important a role in mathematical discovery as did the austere formalism championed by the school of Grothendieck. Thurston's views on the relation between mathematical understanding and formal proof are summed up in his essay "On Proof and Progress in Mathematics." [more inside]

## The Cause of the Formation of Meanders in the Courses of Rivers and of the So-Called Baer’s Law

## bons mots, poems, math, knitting and logic

Entertaining, collected bon mots and surprisingly interesting, collected poems by various authors. From a likable math brainiac's site, Dr T.E. Forster, a Cambridge University lecturer. He also knits and writes about Buddhist logic [pdf]. Bonus, there's a fun gif.