# Proceedings of the Angelic Brew Pub Seminar

Here's some stuff on the integral we discussed on September 27, 2001

Computing the escape velocity of a rocket will give you some insight into the origins of algebraic geometry.

Here is a proof (using transversality theory) that there are 27 lines on a cubic surface.

Here is some number theory relating to a specific difference equation. Eric points out that the characteristic roots of the difference equation G(n)=G(n-1)+G(n-2)+G(n-3) are degree three over the rationals. When the initial conditions are real the solution is of course real, but to write the solution explicitly requires an algrebraic number of degree six.

An exposition of an (unpublished?) theorem of R. H. Bruck on the configuration formed by three tangents to a conic.

A counterexample to L'Hopital's Rule.

A Musical Mnemonic for Logarithms of Small Integers.

In his famous monograph, D. V. Anosov writes "Every five years or so, if not more often, someone `discovers' the theorem of Hadamard and Perron proving it either by Hadamard's method of Perron's. I myself have been guilty of this."

Here is a brief exposition of Arrow's Theorem on the impossibility of a fair election.

An analysis of the Watt linkage (aka the Lemniscoid).

An abstract version of Gronwall's inequality.

Steve and Joel have analyzed the "pancake model" for the collapse of the twin towers. After we did this we found a similar calculation at . http://911research.wtc7.net/wtc/models (Further references appear in the article.)

Here is a calculation of the probability distribution of the angle or rotation of a random rotation.