[FOM] A new definition of Cardinality
T.Forster@dpmms.cam.ac.uk
T.Forster at dpmms.cam.ac.uk
Thu Nov 26 17:50:30 EST 2009
I looked at this a while ago. My recollection is that Jech's technique for
showing that HC (the hereditarily countable sets) is a set - and of rank
omega_2 at most - will generalise to show that H_kappa (the sets
hereditarily of size less than kappa) is a set (and without any use of AC)
works *as long as kappa is an aleph*. I'll have another look to see if the
starred condition is needed. It probably is.
Jech's construction is very elegant. A nice paper
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