## Hmm, Ordinal Numbers...

In the last post, Why Ordinal Numbers, I had intuitively guessed that I would be left with a perfect set after enough application of derived sets on \({S}\). By the end, I gave an example of a set that had a nonempty “infinite” derived set, \({S^{(\infty)},}\) that was not ...

## Why Ordinal Numbers?

It's about time I write on a non-Euler topic -- the birth of ordinals. I've been reading Georg Cantor's *Contributions to the Founding of the Theory of Transfinite Numbers.* In two papers published in 1895 and 1897, Cantor creates the theory of cardinals and ordinals from the ground ...