Monthly Archives: April 2012

A Really Nice Talk About PDE, Numerics (and Pyramids)

Posted on April 30, 2012 by

My previous post recommended a really nice talk by Jonathan Israel about human rights. Here is the link again. It is very recommended. Actually, I was in the audience and after the lecture, at the reception,  I came to the … Continue reading →

Posted in Analysis, Applied mathematics | 1 Comment

The 1789 Declaration of the Rights of Man

Posted on April 27, 2012 by

Today (April 27, 2012) it is precisely 213 years 7 months, and 29 days to the completion of the declaration of the rights of man, which makes it a perfect occasion to celebrate this remarkable human creation. Here is a … Continue reading →

Posted in Law, Philosophy | Tagged | 4 Comments

Galvin’s Proof of Dinitz’s Conjecture

Posted on April 26, 2012 by

Dinitz’ conjecture The following theorem was conjectured by Jeff Dinitz in 1979 and proved by Fred Galvin in 1994: Theorem: Consider an n by n square table such that in each cell (i,j) you have a set with n or more elements. … Continue reading →

Posted in Combinatorics, Games | 6 Comments

Greg Kuperberg: It is in NP to Tell if a Knot is Knotted! (under GRH!)

Posted on April 10, 2012 by

Wolfgang Haken found an algorithm to tell if a knot is trivial, and, more generally with Hemion, if two knots are equivalent. Joel Hass, Jeff Lagarias and Nick Pippinger proved in 1999 that telling that a knot is unknotted is … Continue reading →

Posted in Computer Science and Optimization, Geometry | Tagged | 12 Comments

Exciting News on Three Dimensional Manifolds

Posted on April 1, 2012 by

The Virtually Haken Conjecture A Haken 3-manifold is a compact 3-dimensional manifold M which is irreducible (in a certain strong sense) but contains an incompressible surface S. (An embedded surface S is incompressible if the embedding indices an injection of its … Continue reading →

Posted in Geometry, Updates | Tagged , , | 4 Comments