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Approximating Heisenberg Geodesics

Math - Heisenberg09

A Riemannian approximation of the Heisenberg group is given by declaring the following frame field orthonormal in \mathbb{R}^3:

X_s = \frac{\partial}{\partial x} - y \frac{s}{2} \frac{\partial}{\partial t}, \;\; Y_s = \frac{\partial}{\partial x} - y \frac{s}{2} \frac{\partial}{\partial t} \;\; T_s = \sqrt{1-s} \frac{\partial}{\partial t}

 (note that the T_s has changed from the earlier versions).

There are many ways to approximate horisontal curves in \mathbb{H} by geodesics in the approximations \mathbb{H}_s. Here's one approximation, going from a sphere in Euclidean space to the apple sphere in Heisenberg space, by way of apple sets in the intermediate spaces:

 

 

 

Last Updated ( Tuesday, 23 June 2009 18:10 )

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ComplexHyperbolic0.3.nb

Math - ComplexHyperbolic09

The notebook has been updated with a proper routine for the Clifford Torus animation (see CH0.2.nb), a quick description of extors, and an animation showing a spinal sphere turning into a fan and then into a Clifford torus.

ComplexHyperbolic0.3.nb

 

 

(right click to play)

Last Updated ( Wednesday, 24 June 2009 19:32 )

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Kissinger on Iran - June 17

Et Cetera Res - etc

ComplexHyperbolic0.2.nb

Math - ComplexHyperbolic09

The notebook now has the routines for drawing fans and Clifford tori, objects defined similarly to the spinal spheres:

Last Updated ( Friday, 19 June 2009 17:47 )

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Spinach Dip (cold)

Food - Hors d'Oeuvres and Such

Ingredients:

1 package spinach (10oz), cooked
2 cups sour cream
1 cup mayo
1 can water chestnuts (8oz)
3 green onions, chopped
1 package Knorr vegetable recipe mix

Instructions:

Mix, then chill for 2 hours. 

Notes:

1. This is a good dip, but making it with generic mayo and no water chestnuts didn't work out well.
2. Yes, using a vegetable mix is cheating. I might try replacing it with raw ingredients, but there's lots of various stuff in there. Btw, the recipe is from the Knorr's package.

Last Updated ( Thursday, 11 June 2009 18:49 )

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