Description: The collection of hereditarily size-limited well-founded sets comprise a
set. The proof is that of Randall Holmes at
http://math.boisestate.edu/~holmes/holmes/hereditary.pdf , with
modifications to use Hartogs' theorem instead of the weak variant
(inconsequentially weakening some intermediate results), and making the
well-foundedness condition explicit to avoid a direct dependence on
ax-reg . (Contributed by Stefan O'Rear, 14-Feb-2015)