## Fourth Linkfest

When I launched the First Linkfest, I called it the first “Irregular” linkfest, and I tentatively stand by that, but besides having a handy excuse in case I later deviate, it definitely seems to be starting to look like a regular “every fortnight, on Saturday” kind of thing.

I am learning a lot from doing these linkfests. You’ll notice that starting with this one, I’m getting a little more organized. The main articles are now divided into “Technical” and “Non-Technical”. A word on the Technical articles: some of these are like math department colloquia. A grad student does not generally attend a math department colloquium/read a highly technical blog post to understand it, but rather in hopes of soaking something up through osmosis. So don’t feel bad if a lot of the posts under “Technical” seem to be written in a foreign language: a lot of them seem that way to me as well.

The previous linkfest was Linkfest III.

## Technical

Scott Aaronson: Top 150 computer science events to be decided once and for all

Ngô Quốc Anh: Pushforward (differential) of a smooth map, Flows for Q-curvature problems

John Armstrong: The Implicit Function Theorem, Immersions and Embeddings, Immersions are locally embeddings

John Baez: The Genetic Code, Network Theory (Part 5)

Ken Baker: Seifert surfaces of dual knots

Tim Carlson: Categoricity for Patterns of Order 2 (PDF)

Matthew Compher: Arguing Semantics: the obelus, or division symbol: ÷

David Corfield: Report on Peter Freyd’s Lecture

CTK: 0^{0} – Münchausen’s Syndrome, √(-1) does not exist – A. De Morgan

Mark Eichenlaub: Visualizing Elementary Calculus: Graphs, Tangents, Derivatives

Bill Gasarch: Natural examples of computable functions which aren’t primitive recursive

Hilbertthm90: Witt Vectors Form a Ring, Formal Groups 1

Rhys Jones, Patrick Haufe, Edward Sells, Pejman Iravani, Vik Olliver, Chris Palmer and Adrian Bowyer: RepRap – the replicating rapid prototyper

Emmanuel Kowalski: The other theorem of Burnside

Dick Lipton: Even Great Mathematicians Guess Wrong

Akhil Mathew: IP=PSPACE (Almost), Simplicial sets I

Jeffrey Morton: Explanation, Fundamentals, an Agrippa-type Trilemma

Christopher Olah: Rethinking Topology, Arithmetic Derivative Graph and Thoughts

Igor Ostrovski: Is two to the power of infinity more than infinity?

The Physicist: What is the evidence for the Big Bang?, Is the edge of a circle with infinite radius curved or straight?, As a consequence of relativity, objects becomes more massive when they’re moving fast. What is it about matter that causes that to happen?

Kenneth Regan: Could Euler Have Solved This?

Urs Schreiber: Axioms for Infinitesimal Cohesion

Mike Shulman: Enhanced 2-categories and Limits for Lax Morphisms

Three-Toed Sloth: “Optimal Nonparametric Prediction and Automated Pattern Recognition in Dynamical Space-Time Systems”

Noah Snyder: When confusions annihilate

Terence Tao: A proof of the Fredholm alternative

Ben Webster: Hall algebras are Grothendieck Groups

## Non-Technical

Scott Aaronson: Three museum reviews

Andrew Ash: Show Me The Code

Avoision: To Cull or Surrender: The sad, beautiful fact that we’re all going to miss almost everything

Ruben Berenguel: Doing (Really) Nothing

Matt Bernico: Greenville College IT department purchases new VX6 module

BlueShoe: Why English Teachers Should Study Japanese

Adrian Bowyer: New RepRap extruder design, Rewriting History

Stuart Buck: Educational Waste

Kareem Carr: Don’t be too Risk Averse

Chazisop: Long-term access to information

James Colliander: NSERV Peer Review System is Broken for Mathematics

Timothy Gowers: Is Alternative Vote better than First Past The Post?

Alex Hoban: How to protest like the Japanese

Workshy Joe: Suddenly, Beards Are Everywhere

Khatzumoto: When the universal translators come

Tanya Khovanova: Fractional Voting Power

LabRat: Give Me Space

Izabella Laba: NSERV peer review system: broken and unreliable

Mark Lee: Nitpicking “Terminator”

Michael Lugo: On the inclusion of solutions in textbooks

Hunter Nuttall: The death of online poker

Orchid64: Will Miss #311: Free Calendars

Alex Papadimoulis: The Nondeterministic Hash

Remy Porter: Contract Termination

Sam Shah: Geometry

Ulysses: Weekend Drink Recommendation – the Caliente edition

## Photography and Pictures:

Avoision: I keep the snowmobiles parked out back, The Colorful Mating Ritual of the Tiny Peacock Spider, Photos From Baconfest Chicago, 2011

John Baez: Higher Structures in China II

Ruben Berenguel: Road Trip Through Iceland: Day 7 – From Egilsstaðir to Mývatn passing through Hverir

URBEX Israel: Kfar Saba Flour Mill

Mikko Mononen: Temporary Obstacle Progress

Matt Novak: Giant Babies of the Future (1937), Pet Horse of the Future (1905)

Telefunker: Red Red Wine (Belgium)