Thursday, March 15, 2012

Keepin' it Hyperreal

I haven't posted anything here in a while, so let's do something cool... like construct $^*\mathbb{R}$
Swag.

The hyperreals, $^*\mathbb{R}$, (Abraham Robinson's world of nonstandard analysis) are a neat way to rigorously develop the notion of infinitesimal numbers in analysis.  Because we want our numbers to form a field, that means we'll also pick up a new description of 'infinitely large' numbers (quite distinct from the cardinals/ordinals though).

This will be more about the crazy set theory shenanigans that go into building $^*\mathbb{R}$, rather than actually working in  $^*\mathbb{R}$... maybe I'll cover the practical side in another blogpost...