[FOM] Some historical questions

[Alasdair Urquhart]

"Hartogs' Theorem" usually refers to a result in complex analysis.
The result in set theory is often described as "Hartogs' Lemma".

Hartogs's 6 page paper of 1914 is devoted to a new proof of
the well ordering theorem.  Hartogs deduces the theorem from
the assumption that any two infinite sets are comparable
(there is a bijective mapping from one into a subset of the
other).

You can see the original paper easily online by looking
at the Wikipedia article on "Hartogs number" and clicking
on the link in the list of references.  I haven't studied
the article carefully enough to see just how the lemma
in question is proved in the paper.